We have in the foregoing a remarkable isothermal result. The heat of compression is so thoroughly absorbed that the thermal loss is only 1.6 per cent.; but the loss by friction of the engine is 14.5 per cent., and the net economy of the whole system is no greater than that of the best American dry compressor, which loses about one-half the theoretical loss due to heat of compression, but which makes up the difference by a low friction loss.

The wet compressor of the second class is the water piston compressor, Fig. 18.



The illustration shows the general type of this compressor, though it has been subject to much modification in different places. In America, a plunger is used instead of a piston, and as it always moves in water the result is more satisfactory. The piston, or plunger, moves horizontally in the lower part of a U shaped cylinder. Water at all times surrounds the piston, and fills alternately the upper chambers. The free air is admitted through a valve on the side of each column and is discharged through the top. The movement of the piston causes the water to rise on one side and fall on the other. As the water falls the space is occupied by free air, which is compressed when the motion of the piston is reversed, and the water column raised. The discharge valve is so proportioned that some of the water is carried out after the air has been discharged. Hence there are no clearance losses.

This hydraulic compressor seems to have a certain charm about it, which has resulted in its adoption in Germany, France and Belgium, and by one of the largest mines in the United States. Its advantages are purely theoretical, and without certain adjuncts which have been in some cases applied to it, even the theory is a very bad one.

The chief claim for this water piston compressor is that its piston is also its cooling device, and that the heat of compression is absorbed by the water. So much confidence seems to be placed in the isothermal features of this machine that usually no water jacket or spray pump is applied. Mr. Darlington, who is one of the stanch defenders of this class of compressors, has found it necessary to introduce "spray jets of water immediately under the outlet valves," the object of which is to absorb a larger amount of heat than would otherwise be effected by the simple contact of the air with the water-compressing column. Without such spray connections, it is safe to say that this compressor has scarcely any cooling advantages at all, so far as air cooling is concerned. Water is not a good conductor of heat. In this case only one side of a large body of air is exposed to a water surface, and as water is a bad conductor, the result is that a thin film of water gets hot in the early stage of the stroke and little or no cooling takes place thereafter. The compressed air is doubtless cooled before it gets even as far as the receiver, because so much water is tumbled over into the pipes with it, but to produce economical results the cooling should take place during compression.

Water and cast iron have about the same relative capacity for heat at equal volumes. In this water piston compressor we have only one cooling surface, which soon gets hot, while with a dry compressor, with water jacketed cylinders and heads, there are several cold metallic surfaces exposed on one side to the heat of compression, and on the other to a moving body of cold water.

But the water piston fraternity promptly brings forward the question of speed. They say that, admitting that the cooling surfaces are equal, we have in one case more time to absorb the heat than in the other. This is true, and here we come to an important class division in air compressing machinery—high speed and short stroke as against slow speed and long stroke. Hydraulic piston compressors are subject to the laws that govern piston pumps, and are, therefore, limited to a piston speed of about 100 feet per minute. It is quite out of the question to run them at much higher speed than this without shock to the engine and fluctuations of air pressure due to agitation of the water piston. The quantity of heat produced, that is, the degree of temperature reached, depends entirely upon the conditions in the air itself, as to density, temperature and moisture, and is entirely independent of speed. We have seen that it is possible to lose 21.3 per cent. of work when compressing air to five atmospheres without any cooling arrangements. With the best compressors of the dry system one-half of this loss is saved by water jacket absorption, so that we are left with about 11 per cent., which the slow moving compressor seeks to erase. We are quite safe in saying that the element of time alone in the stroke of an air compressor could not possibly effect a saving of more than half of this, or 51/2 per cent. Now, in order to get this 51/2 per cent. saving, we reduce the speed of an air-compressing engine from 350 feet per minute to 100 feet per minute. We must, therefore, in one case have a piston area three and one-half times that of the other in order to get the same capacity of air, and in doing this we build an engine of enormous proportions with heavy moving parts. We load it down with a large mass of water, which it must move back and forth during its work, and thus we produce a percentage of friction loss alone equal to twice or even three times the 51/2 per cent. heat loss which is responsible for all this expense in first cost and in maintenance, but which really is not saved after all unless water injection in the form of spray also forms a part of the system.

It is obvious that cost of construction and maintenance have much to do with the commercial value of an air compressor. The hydraulic piston machine not only costs a great deal more in proportion to the power it produces, but it costs more to maintain it, and it costs more to run it. It is not an uncommon thing to hear engineers speak of the hydraulic piston compressor as the "most economical" machine for the purpose, but that it is so "expensive" and takes up so much room, and requires such expensive foundations that, unless persons are "willing to spend so much money," they had better take the next best thing, a high speed machine. We hear of "magnificent air-compressing engines, the largest in the country," and pilgrimages are made to see these artificial wonders when, not unlike the old pyramids, they represent a pile of inert matter—a monument to moneyed kings.

The hydraulic piston compressor has one solitary advantage, and that is, it has no dead spaces. It was conceived at a time when dead spaces were very serious conditions—were positive specters! Valves and other mechanism connected with the cylinder of an air compressor were once of such crude construction that it was impossible to reduce the clearance spaces to a reasonable point, and, furthermore, the valves were heavy and so complicated that anything like a high speed would either break them or wear them out rapidly, or derange them so that leakages would occur. But we have now reduced inlet and discharge valves and all other moving parts connected with an air cylinder to a point of extreme simplicity. Clearance space is in some cases destroyed altogether by what is, as it were, an elastic air head which is brought into direct contact with the piston. All this reduces clearance to so small a point that it has no influence of any consequence. The moving parts are made extremely simple, even arriving at a point where inlet valves are opened and closed by their natural inertia. Mr. Sturgeon, of England, has applied a most ingenious and successful inlet valve, which is opened and closed by the friction of the air piston rod through the gland. We have, therefore, reached a point at which high speed is made possible.

Long-stroke air compressors are evidently objectionable on the basis of greater expense of construction. All the parts must be larger and heavier. The fly wheels are increased enormously in diameter and weight, and the strength of bearings must be enlarged in proportion. It is difficult to equalize power and resistance in air compressors with long strokes. The speed will be jerky, and when slow, the fly wheel rather retards than assists in the work of compression. This action tends to derange the parts and makes large bearings a necessity. The piston in a long-stroke compressor travels through considerable space before the pressure reaches a point where the discharge valve opens, and after reaching that point it has to go on still further against a prolonged uniform resistance. This makes rotative speed difficult. During the early part of the stroke, the energy of the steam piston must be stored up in the moving parts, to be given out when the steam pressure has been reduced through an early cut-off. With a short stroke and a large diameter of steam cylinder we are able to get steam economy or early cut-off and expansion without the complications of compounding.

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[Continued from SUPPLEMENT, No. 793, page 12677.]



THE POWER OF WATER, OR HYDRAULICS SIMPLIFIED.

By G.D. Hiscox.

CURRENT WHEELS FOR POWER AND RAISING WATER.

The natural flow of water in a current is probably one of the oldest and cheapest of the methods for obtaining power, or the lifting of water within moderate elevations, for a supply for irrigation and domestic purposes; and we propose, apart from the current wheel, to treat only of self-water-raising devices in this chapter.

Water wheels of various forms for this purpose have been used from time immemorial in Europe, Asia and Egypt, where the record gives examples of wheels of the noria class from 30 to 90 feet in diameter; the term noria having been applied to water wheels carrying buckets for raising water; the Spanish noria having buckets on an endless chain.

Records of a Chinese noria, of 30 feet diameter, made of bamboo, show a lifting capacity of 300 tons of water per day to a height of 3/4 of the diameter of the wheel—velocity of current not stated.

For less quantity and greater elevation, these forms of wheel may have pumps attached to the shaft, by crank, that will give a fair duty for a high water supply.

For power purposes, as in the plain current wheel, Fig. 23, there are two principal factors in the problem of power—the velocity of the current and the area of the buckets or blades.



Their efficiency is very low, from 25 to 36 per cent., according to their lightness of make and form of buckets. A slightly curved plate iron bucket gives the highest efficiency, thus ( to the current, and an additional value may also be given by slightly shrouding the ends of the buckets.

The relative velocity of the periphery of the wheel to the velocity of the current should be 50 per cent. with curved blades for best effect.

The most useful and convenient sizes for power purposes are from 10 to 20 feet, and from 2 to 20 feet wide, although, as before stated, there is scarcely a limit under 100 feet diameter for special purposes.

In designing this class of wheels special attention should be given to the concentration and increase of the velocity of the current by wing dams or by the narrowing of shallow streams; always bearing in mind that any increase in the velocity of the current is economy in increased power, as well as in the size and cost of a wheel for a given power.

The blades in the smaller size wheels should be 1/4 of the radius in width, and for the larger sizes up to 20 feet, 1/5 to 1/6 of the radius in width and spaced equal to from 1/4 to 1/3 of the radius.

They should be completely submerged at the lowest point.

For obtaining the horse power of a current wheel, the formula is

Area of 1 blade x velocity of the current in ft. per sec. ————————————————————————————— 400

x by the square of difference of velocities of current and wheel periphery = the horse power; or

A x V 2 ——— x (V - v) = h. p. 400

[TEX: frac{A imes V}{400} imes (V - v)^2 = h. p.]

in which A equals the area of blade in square feet, V and v velocities of current and wheel periphery respectively, in feet per second. Thus, for example, a wheel 10 feet in diameter with blades 6 feet long and 1 foot in width, running in a stream of 5 feet per second—assuming the wheel to be giving as much power as will reduce its velocity to one half that of the stream—the figures will be

6' x 5' 2 ———- x 2.5 = 0.468 400

[TEX: frac{6' imes 5'}{400} imes 2.5^2 = 0.468]

horse power of the wheel.

The total power of the stream due to the area of the blade equals the

Square of the velocity of the stream —————————————————— x Twice gravity (64.33)

volume of water in cubic feet per second x 62.5 (weight of 1 C') = the value or gross effect in pounds falling 1 foot per second. This sum divided by 550 = horse power. Thus, as per last example,

2 5 ——— x 30 x 62.5 64.33 ——————————— = 1.32 the horse power of the current 550

[TEX: frac{frac{5^2}{64.33} imes 30 imes 62.5}{550} = 1.32 ext{ the horse power of the current}]

due to the area of the blades of the water wheel.

For the efficiency of this class of wheel, with slightly curved and thin blades, divide the horse power of the wheel by the horse power of the current area, equals the percentage of efficiency.

As in the last case,

0.468 / 1.32 = 0.351/2

per cent. efficiency of the water wheel.

With higher velocities of stream and wheel the efficiency will be from 2 to 3 per cent. less, although the horse power will increase nearly with the increase in velocity of the current.

For details of application of various forms of current wheels for power purposes see illustrated description Yagn's and Roman's floating motors in SCIENTIFIC AMERICAN SUPPLEMENT, No. 463.

A very good example of a floating motor of the propeller class is Nossian's fluviatile motor, illustrated and described in SCIENTIFIC AMERICAN SUPPLEMENT, No. 656.



Fig. 24 represents a very complete floating motor, in which the floats are wedge shaped at the stem, for the purpose of increasing the current between them, the wheel being an ordinary current wheel, as shown in Fig. 23, with a curved shield or gate in front, which can be moved around the periphery of the wheel for the purpose of regulating its speed or stopping its motion by cutting off the stream from the buckets.

The float, rising and falling with the stream, is held in position by a braced frame swinging on anchorages within the mill on shore, and parallel with a swiveled shaft.

Tide wheels and tidal current wheels have been in use for more than 800 years, and were largely in use in Europe and the United States during the first half of the present century. No less than three were running in the immediate vicinity of New York, in 1840, for milling purposes.

Their day seems to be past, except in some special localities. We will also pass them, and illustrate some of the

SELF-ACTING WATER-RAISING DEVICES.

The tympanum derives its name from its similarity to a drum as made by the Romans, but its origin was Egyptian. It is a current wheel with frame like Fig. 23, to the outside of which a set of chambers or tubes are fixed, radiating spirally, so as to lead the water to the shaft as the wheel revolves, as shown in Fig. 25. It has a lift of a little less than half its diameter, and answers an excellent purpose for the irrigation of rice and cranberry fields, or on streams running through low lands in arid districts. It is still one of the Nile irrigating wheels.



The building of these wheels is within the scope of the carpenter and the tinsmith. A short wooden shaft made square or octagonal, as convenient, with gudgeons in the ends and arms of wood bolted across each of the sides of the shaft, or as shown in the cut, will form a frame work upon which a rim may be fastened, to which the blades and tubular buckets can be attached.

The directions in regard to the current wheel, Fig. 23, may be followed as to number and form of blades, which must be made in length and width proportional to the velocity of the stream and the quantity of water to be lifted by each tubular arm. The tubes may be made of galvanized sheet iron and attached to the outside of the wheel, as shown in Fig. 25.

THE NORIA OR BUCKET WHEEL.

This is a simple current wheel with pot buckets, rigid or swinging, arranged on the rim of the wheel, to carry up and discharge the water nearly at the top of the wheel, and through the long ages that it has been in use for irrigation, village water supply, and even for private establishments, has assumed a variety of forms in detail of construction ranging from the bamboo wheels of the Chinese to the light iron wheels of modern construction.

We illustrate the most simple of these forms in Figs. 26 and 27, in which the first is a series of boxes or chambers in the rim of the wheel with side openings in the forward part of the box as the wheel revolves, and a lip extending from the inner edge of the opening to direct the outflow into the trough.



Another form, Fig. 27, is arranged with swing buckets or pots, pivoted just above their centers, and with the catch trough so fixed as to tip the buckets at the highest point, thus giving this wheel the greatest possible advantage as to height of discharge for a given diameter.



The power value of these wheels for raising water is a matter of computation as nearly reliable as for other devices for the same purpose, when the velocity of the current is known at the point of contact with the blades.

The horse power of the wheel may be computed as for the current wheel, Fig. 23, and, as the horse power is equal to 33,000 pounds raised one foot high per minute, we may assume a construction of wheel that will allow of discharging at 8 feet above the stream; then 33,000 / 8 = 4,125 pounds of water discharged at 8 feet elevation per horse power per minute. As the net power of the wheel in the last example, for Fig. 23, was 0.468 of a horse power, then 4,125 x 0.468 = 1,930 pounds of water raised 8 ft. per minute by the size of bucket and velocity of current in that case. From this a deduction of 20 per cent. should be made for loss by spill and imperfect construction, so that 1,500 pounds or 176 gallons per minute would be the probable output—over 253,000 gallons per day; or, for irrigating purposes, equal to a rainfall of over 11/4 inches in depth on 50 acres in one week.

The proportion of capacity of the lifting buckets for such a wheel becomes of as great importance as its efficiency.

If the buckets are too large, the wheel will stall, and if too small, the wheel will not give its full duty.

For obtaining the approximate capacity of the lifting buckets, assuming the example as above computed, a 10 foot wheel with the velocity at periphery of 21/2 feet per second is 150 feet per minute, or five revolutions per minute, nearly. Then 1,930 lb. per m. / 5 revolutions = 386 pounds water capacity for all of the buckets on the wheel.

If such a wheel is constructed with 16 blades and 16 buckets, one between each blade, then 386 / 16 = 24 pounds for each bucket, or 38 / 100 of a cubic foot.

The spill from this capacity of bucket being sufficient to compensate for the friction of the shaft journals.

The lifting buckets of the noria class, Figs. 26 and 27, can be made of positive dimensions to suit the computations as above; but those of the tympanum class, Fig. 25, should be made of dimensions to conform with the required capacity at the moment of leaving the water, as the water at this point flows into the arm.

(To be continued.)

* * * * *

To remove paint and varnishes, which resist the action of strong lye, Dr. Stockmeier recommends a mixture of water of ammonia, two parts, and turpentine, one part; this applied to the surface to be cleaned will, after a few minutes' action, enable the paint to be removed by use of cotton waste or similar material.—(Bayr. Gen. Ztg.), Rundschau.

* * * * *



ON GAS MOTORS.

M. Witz, says the Gas World, has been conducting a series of experiments on the Delamare-Deboutteville and Malindin gas engine, driven by Dowson gas, and in which the gas generator takes the place of the ordinary steam boiler. The engine was a one-cylinder motor in the establishment of Messrs. Matter & Co., Rouen. Its power was 100 horse indicated; the cylinder was 23 inches in diameter, the stroke 38 inches, and the normal speed 100 revolutions. The engine is of the Simplex type; the kindling is electric; the cycle of operations is fourfold, with powerful compression. The Dowson generator is 30 inches inside diameter and 76 inches in height from the bars to the top. Air is blown in by steam driven in under the hearth. There is a siphon, a coke scrubber 110 inches high, a sawdust purifier, and a gasholder of 750 cubic feet capacity, and a pipe to the engine 5.2 inches in diameter. The total area occupied by this apparatus is 140 square yards, of which two-thirds are built on. The anthracite employed was from Swansea, containing 5.4 per cent. of ash. The observations made with a string friction brake were continued for 68 hours, everything used being carefully weighed and measured. One day the machine was worked for 151/4 hours on end; the other days it was worked with an interval of half an hour every 12 hours to clear the hearth, poke the fire and lubricate the machine; and it was clearly established that with a big enough generator it would be quite possible to work continuously for several days.

The following were the data for a day of 24 hours, with an interval of half an hour: 8:55 P.M. one day to 8:55 P.M. the next, interval 8:30 to 9 A.M. Anthracite used, 18.4 cwt.; coke used, 3.42 cwt.; water used for steam injection, 217.3 gallons; water used in scrubber, 4,106 gallons; water used in cooling the cylinder, 20,000 gallons; oil used in cylinder, 14.84 pounds; grease, 1.8 pounds; revolutions of machine, 142,157, or 100.8 per minute; effective work, 75.86 French horse power, or 77.4 British; gas used, 6,742 cubic feet per hour, at 772 mm. pressure and 70.7 deg. F., or 83.7 cubic feet per effective horse power; efficiency, 69 per cent.

Now, with regard to the comparison between the large gas motors and steam engines of the same size, M. Witz goes on to remark that the gas engine is by no means, as was formerly thought on high authority, necessarily restricted to the domain of smaller work and sizes. Even in early times it was seen that the gas engine belonged to a type in which there were possibilities of improvement greater than those available in the steam engine, because the difference of temperature between the working substance in its hotter and its cooler condition was greater than in the steam engine; and consumptions of 5,250 cubic feet per horse power per hour soon descended step by step as far as 2,060, while the power went up, past 4, 8 and 12, to 25 or 50 horse power; and in the exhibition of 1889 there were gas engines seen in which the explosion chamber had a diameter of as much as 23 inches.

But the price of coal gas seemed to be too high for use in these large engines, in which sizes steam is comparatively cheap; and so poorer gas, which, though possessing only about 28 per cent. of the heating power, is still cheaper in proportion than coal gas, when it is made on the spot, was introduced to tide over the difficulty. Difficulties have been successively overcome, with the result which we have just seen, namely, 1.37 pounds of anthracite per effective horse power, or about half the carbon which a steam engine of the same power of excellent design, and well kept up, would consume. A 50 horse simplex at Marseilles, in Barataud's flour mill, is said to have run for the last 2 years on 1.12 pounds of English anthracite per effective horse power; and thus M. Witz says his predictions of 10 years ago, that the gas producer would some day replace the boiler, are being verified in such a way as to surprise even himself.

But the objection is stated, and it is a serious one: the weight of fuel is not the only thing to be considered. The steam engine uses coal, the producer requires English anthracite, which is dearer; the gas motor uses a great deal of water and a great deal of oil, which cost money; and gas motors are dear, while gas producers and their adjuncts cost a tidy bit of money, and wear out pretty fast. Is not steam, after all, more economical in the long run? Besides, producers are bulky and take up a great deal of space; the weight of fuel is only one element in a complicated problem.

In order to study the grounds of this objection, M. Witz has instituted a comparison between the actual cost of large steam engines and that of gas motors of similar size.

Take a good Galloway or multitubular boiler; for 75 horse power effective the heating surface must be at least 74 square feet. Using good Cardiff coal, with 4 per cent. of ash, and a heating power of 15,660 Fahr. units; the steam raised will be 8 to 9 pounds per pound of coal, so that 9,400 to 10,577 Fahr. units are utilized in raising steam, or 68 to 76 per cent., which is an excellent result. Take an engine of 16 inch cylinder diameter, 40 inch stroke, and 66 revolutions, etc.; it will use 22.4 pounds of steam per horse power effective, which represents 2.47 to 2.8 pounds of coal under the boiler. These 10 pounds of steam carry 11,752 Fahr. units of heat, and produce work equal to 75 horse, or 1,143 Fahr. units of heat; which corresponds to an efficiency of 9.7 per cent. In a gas motor, on the other hand, we find the materials employed, as per the above data, to contain 8,958 Fahr. units of heat, and to make gaseous fuel in which 6,343 units are available; a return of 70.6 per cent, in the producer. The motor receives these 6,343, and converts 1,143 of them into work; an efficiency of 18 per cent. In order to be equivalent from the heat point of view, a steam engine ought to produce a horse power effective per 9.72 pounds of steam at 5 atmospheres; but no such steam engine exists.

M. Witz goes on with comparative estimates. For a Corliss engine and boiler, with chimney, etc., complete, and putting these up, he allows L1,280; for a Simplex gas motor and Dowson producer complete, including putting up, he allows L1,290, which he explains to be average actual prices; but these prices do not cover cost of transport, and M. Witz does not go into cost of masonry for buildings, apart from foundations, etc., for the apparatus and machinery.

As to water, the gas motor takes 215 cubic feet per horse power effective. A condensing steam engine uses five times as much.

The lubricating oil used at Rouen was a mixture of Russian oil at 430 fr. per ton, and Ferry and Heduit F.H. oil at 900 fr.; the average was 650 fr. per ton, or 2.8d. per pound. Wanner grease, at 6.4d. per pound, was used for the moving parts. A steam engine requires less oil for the cylinder, but the same quantity for the moving parts.

The attendance on the gas motor is too much for one man, not enough to occupy two; reckon it at 4s. 91/2d. a day.

These elements enable us to calculate the daily cost of the gas motor, of 75 actual horse power, in comparison with a steam engine of the same size.

Steam Engine.

s. d. Upkeep, interest and sinking fund at 15 per cent, on L1,292 = L193.8 = per day. 12 11 Cardiff coal, 2.643 pounds per actual horse power per hour; 2.643 x 10 x 75 = in 10 hours 1,982 pounds coal at 22s. a ton. 19 51/2 Oil, 3.36 pounds per day at 2.8d. per pound. 0 91/2 Grease, 0.67 pound at 6.4d. 0 41/2 Wages. 4 91/2 ————- L1 18 4

Gas Engine.

s. d. Upkeep, interest and sinking fund at 15 per cent. on L1,292 is, per day. 12 11 Anthracite, 1.156 pound per actual horse power per hour = for 750 horse-hours, at 25s. 6d. 9 10 Coke, 0.215 pound x 10 x 75 = 1611/4 pounds at 28s. 2 0 Oil, 0.0084 pound per actual horse power per hour, or 0.0084 x 10 x 75 = 6.28 pounds at 2.8d. 1 51/2 Grease, 0.754 pound per day at 6.4d. 0 5 Electric kindling, on cost. 0 31/2 Wages. 4 91/2 ————- L1 11 8

The big gas engine making its own poor gas, and running 10 hours a day, has thus the best of it in the comparison with the steam engine of equal power.

* * * * *



A PROJECTING APPARATUS FOR BALANCES OF PRECISION.

The luminous projection apparatus illustrated herewith, when adapted to a balance of precision, permits of effecting weighings very rapidly. For the same approximation, the velocity of oscillation becomes five or six times greater, and, by the method employed, the last centigrammes and the milligrammes and their fractions are estimated directly, with immediate verification. As the apparatus is independent of the parts of the balance, it can be placed on all the existing laboratory balances of precision.



The modification introduced into the balance consists in the displacing of the center of gravity of the beam in such a way as to diminish the sensitiveness, and consequently to obtain a much greater velocity, and then, by optical means, to considerably increase the amplitude of the oscillations.

Instead of the oscillations being observed through the microscope, they are projected upon a divided screen forming a dial, the division of which is seen by transmitted light.

The apparatus consists of a small achromatic objective placed at the extremity of the tube of a microscope, in which there is a divided screen that receives the enlarged image of the reticule fixed upon the needle. Upon this reticule are projected the rays (condensed by a powerful lens) that come from a luminous source placed behind the balance. The focusing is done by means of a rack and pinion.

The luminous source employed is a gas burner with reflector. This is placed in a walnut box in order to prevent any projection of heat upon the balance. This burner, thus isolated, is lighted for but one or two minutes at a maximum, at the end of each weighing. So, on fixing a thermometer in the cage, we find that no variation, ever so slight, occurs in the temperature. In order to effect a weighing, the gas being turned down to a taper, we proceed as with an ordinary balance until the extremity of the needle no longer emerges from the lower dial. Then we count the difference of the number of the divisions made by the needle to the right and left of zero. This difference, multiplied by the approximate value, in milligrammes, of each division of this dial (value given by the instrument) immediately gives the number of centigrammes and milligrammes that must be added to the weights already placed upon the pan of the balance in order to obtain an equilibrium, to about a half division of the lower dial.

The value of each division of this dial varies from 3 to 10 milligrammes according as the balance shows 0.1 or 0.5 milligramme. As the dial has 10 divisions on each side of the central mark, we thus estimate, without tentatives, the three last centigrammes or the last decigramme, according to the sensitiveness.

At this moment the doors of the cage are closed, in order to prevent draughts of air, the gas is turned on by means of a regulating cock, and the balance is manipulated by first lowering the beam and then bringing the pans to a standstill. We then read the difference of the divisions traversed to the left and right upon the luminous dial through the image of the reticule. The images are reversed upon the dial, but practice soon causes this petty difficulty to disappear. This number of divisions indicates the number of milligrammes and fractions of a milligramme by which it is necessary to shift the counterpoise on its arm in order to obtain a perfect equilibrium, which latter is verified by a simple reading. Every half division of the dial corresponds, as to weight, to the sensitiveness indicated for the instrument.

With a little practice a weighing effected as above described takes but a quarter or a fifth of the time that it does with an ordinary balance.—Revue Industrielle.

* * * * *



STARCHES FOR THE FINISHING OF COTTON FABRICS.

The starches have been classified by Dr. Muter, according to the appearance they give under the microscope, into five groups:

Class I.—Hilum and concentric rings visible. All the granules, oval or ovate. Tous-le-mois, potato, arrowroot, etc.

Class II.—The concentric rings are all but invisible, the hilum is stellate. Maize, pea, bean, etc.

Class III.—The concentric rings are all but invisible, also the hilum in the majority of granules. Wheat, barley, rye, chestnut, etc.

Class IV.—All the granules truncated at one end. Sago, tapioca, etc.

Class V.—All the granules angular in form. Rice, tacca, arrowroot, oats, etc.

The principal starches used for finishing cotton fabrics are potato (farina), wheat, Indian corn (maize), rice, tapioca, arrowroot, sago; the last three not so often as those previously named.



* * * * *



MARBLE AND MOSAIC.

[Footnote: A paper recently read before the Architectural Association, London.—From the Architect.]

By T.R. SPENCE.

I do not propose to enter into any historical details as to the first and subsequent application of mosaics. In a general sense we understand mosaic as a combination of various more or less imperishable materials—fixed together by cement or other adhesive substances—and laid over walls, floors, etc., with a view to permanent decorative effect. The substance of the tesserae is of many kinds, namely, glass, cheap and precious marbles, hard stone, and burnt clay, these mentioned being mainly in use for architectural purposes. For decorative schemes we collect as many gradations of color as are obtainable in such durable materials in their natural or manufactured state, and thus form a color palette which we regard in the same sense as a painter would his pigments.

Of course, the first proceeding is to prepare a design on a small scale, which shall embrace your notions of color only. Then follows a full-sized cartoon, which I need hardly add shall embrace your best efforts in drawing. A tracing is made of the latter and transferred to sheets of cardboard. This cardboard is cut to the size of certain sections of your design, and, for convenience, should not be more than, say, 20 in. square. Of course, it will not always be square, but will bear the same relation to your complete cartoon as a map of the counties would to that of all England. Now, working from the small design (of color), the tesserae are cut to the forms required, laid face downward, and glued on to the cardboard sections containing your enlarged cartoon. When the design is all worked out on these sections they are ready for fixing on walls or floor by laying them home on a float of cement. When the cement sets, the cardboard sticking to the face is washed off, and the joints of tesserae flushed over with cement and cleaned off, leaving all joints filled up level.

There are other processes used for the same end. The technical processes need not occupy our attention at present. There is one process that may appeal to you, and that is executing the work in situ by floating on a limited expanse of cement, and sticking on the tesserae at once. It has the advantage of enabling the artist or architect to see the effect of his efforts under the fixed conditions of light and height.

I shall confine myself to vitreous or glass mosaic, which for durability, extended scales of primary colors and their numerous semi-transparent gradations is unequaled by any substance yet used for wall or floor decoration. I am surprised, having all these fine qualities, it is not more used by architects. If you require proofs of its triumphs, go to St. Mark's, of Venice, and stand under its mellow golden roof. There you will find its domes and vaulted aisles, nave and transepts entirely overlaid with gold mosaic, into which ground is worked—in the deepest and richest colors and their gradations that contemporary manufacturers could produce—subjects selected from the creation down to the life of Christ, in addition containing a complete alphabet of early Christian symbolism. The roof surfaces being one succession of over-arching curves become receptive of innumerable waves of light and broad unities of soft shadows, giving the whole an incomparable quality of tone and low juicy color.

Never use your gold but on curved or undulating surfaces. Flat planes of gold only give the effect of a monotonous metallic yellow, and can never be beautiful, owing to the absence of the variations that come with waves of shadow. By letting out the reins of imagination we might feel that in this a tenth century Giorgione has given off the mental impressions of all the golden autumn of his life. His material gave him an advantage over his great followers of the fifteenth and sixteenth centuries, insomuch that glass has a living and glowing quality of light not existing in the somewhat clouded purity of oil or fresco.

In St. Mark's we have an example of the superb treatment in deepest and most Titianesque scales applied to curved forms, but to find a similarly complete example of the use of lighter tones and on flat surfaces, we must turn to Ravenna. I can give you no adequate description of the wall mosaics of Ravenna. In the sense of delicate color they remind me of some of the subtile harmonies of many of the finest works of the modern French school—of the Impressionists and others who combine that quality with a true instinct for design. In standing before them you feel that the Dagnan Bouverets, the Mersons, the Cazins, the Puvis de Chavannes, etc., of the fifth century have had a hand in the conception and realization of the beautiful compositions to be found on the nave walls of the two churches of St. Appollinare Nuovo and St. Appollinare in Classe. Here all the scales are of delicate degrees of light tones, supreme in their beauty, completeness, and, most important to us, their true decorative instinct. In the Baptistery we find what I may term a third essay in color, by weaving in rich, dark, and glowing colors on figures and bold sinuous forms of ornament in such a skillful and judicious manner that the whole dome seems to be alive with harmonies, although they are mostly primaries.

As you know, rules for the disposition of color are futile, yet some details that struck me as eminently satisfactory may interest you. In all cases the tesserae are of small dimensions, about a quarter of an inch square. The stucco joints are large and open, surfaces far from level, but undulating considerably. The tesserae stick up in parts, brilliant edges showing. Absence of flatness gives play to the light. The gray of the stucco joints brings the whole composition together, serving as cool grays in a picture to give tender unity. Gold, apart from backgrounds and large surfaces, is used very cleverly in small pieces in borders of garments, and more especially in thin outlines to make out the drawing and certain flowing forms of ornament. Brilliant pieces of glass actually moulded at the kiln into forms of jewels add brilliancy to crowns, borders, etc. These stick boldly out from the surface. I noticed in the Baptistery below the springing of the dome a frieze about 2 ft. 6 in. deep, having the ground entirely in black, through which was woven in thin gold lines a delicate foliated design. This, in conjunction with the upper surfaces in dark, rich color, had a most delightful effect.

We, as students, can learn most from the Ravenna examples, for great are the needs of light and silvery color in this country, where gray and gloomy days far outnumber those in which the sun gives liberally of his light. I may say, in passing, as our subject is really a matter of decoration, that our nineteenth century efforts in this direction are all of a somewhat gloomy tendency. We fill our rooms with imitations of somber Spanish leather, stain and paint our woodwork in leathery and muddy tones, to arrive at what is now a sort of decorator's god. Quaintness is the name of that god. Many are the sins for which he has to answer. Had we not better worship a deity called beauty, whose place is a little higher up Parnassus? Why should we not in our endeavors attempt in some measure to transfix the brilliant harmonies that follow the sun in his liberal and gracious course? This muddy quaintness is certainly pleasant for brief periods, when lamps are low and fire light gilds and deepens its parts. Turn the sunlight on these so-called triumphs of the modern decorator's art, and then you feel the lack of many a phase of color that might have been borrowed from the thousand and one examples that in nature he vivifies and makes brilliant.

Referring again to the Ravenna mosaics, I can only add that at the present day an extended palette of colored glass is available. The technical difficulties are not great, and there is no question as to the fine qualities of design and color that are to be obtained in this material. The great point in this, as in all other schemes of decoration, is the art, the mental quality of conception, and the sense of color and fitness. If we hold the precious heritage of an artist's mind—that divine and rare something which gives form, color, and completeness to a story, a dream or a vision—then very little difficulty follows in making vitreous mosaic a valued servant in the realization of a fine creation.

It is the function of architects to design suitable spaces for color decoration, so bound in by dignified mouldings and other details of his constructive art, in such a manner that the addition of decorative color shall in no way mar the scheme of his complete work, but shall (under these well ordered distributions) have set on them the seal and crown of color which is inseparable from a perfect piece of architecture. In such spaces he may dream his dreams, tell his stories, and stamp on them for centuries his subtilest and divinest thoughts. May I not urge that to such spaces must be given the best that is in you? for once placed so shall they remain unchanged through generations, time being powerless to add any mellow garment of tone or softening quality whatever.

I mistook the title of the subject in thinking that it was mosaic only, and at the last moment found it was marble and mosaic. However, the same dominant principles shall underlie the treatment of marble. It is a question of the finer instincts for form and color.

In recent years the demand for choice decorative materials has been the means of opening out many marble quarries all over the world. Transit being easy, a large scale of varieties is available. One fine addition is the Mexican onyx. My feeling is that the most beautiful marbles are those where the soft and sinuous veins melt and die into the general body, comparatively sharp markings dying right away at the edges into innumerable gradations. Marbles having strong and hardly marked veins present great difficulties in distribution. If they are near, they offend you with their coarseness; and, placed at a distance, the hard vein lines have very little decorative value. I should say use these in narrow slips, with very little moulded profile or as parts of intazzio.

Mouldings should be specially designed for different marbles. I should say mainly on the principle of sudden contrasts; that is, large members with very little curve bound with members very small in detail, thus obtaining sharp lines, having little surface to be influenced or distorted by the veined markings, and serving to sharpen up and give form to the broader members (which show the color qualities of the marble), much as you sharpen up an ink drawing by underlining. These small members serve the architect's purpose for the expression of vertical and horizontal lines, and where decisive and cutting shadows are required in the composition of his work.

If delicate carving forms part of your design, I should say statuary is the best, as you have no veins to distort your detail. I need hardly add that economy should be studied in using precious marbles, without injuring the durability of the work. Contours may be built up in thin sections.

Intazzio is a beautiful form of treating marble on an inexpensive ground. Gem-like effects may be obtained by inlaying with smaller pieces, following such ornamental forms as your inventive brains shall dictate. Perhaps the pockets of your clients will be the chief dictator.

Heraldic emblazonings, inlaid in marble, are highly effective. The conditions of the heraldry necessitate the use of many varieties, but in such small quantities that on a large simple field they are rarely out of harmony. In addition they map out a large and interesting variety that will save the worry of creation of designs coming entirely from your own brain, and you know the worry of an architect's life makes him hail with pleasure at times a rest from the strain of creation. This heraldic work may be seen to perfection in the chapel of the tombs of the Medici at Florence.

At the Pitti Palace are some tables which you may know where marble intazzio can no further go. Alabaster does not appeal to me, it is somewhat sugary in results. If you are fortunate enough to have a sculptor who is a sort of nineteenth century Donatello, let him work his will on statuary or such restful marble.

The celebrated monument in the church of S. Giovanni Paulo, at Venice, which Ruskin says is the finest monument in the world, if my recollection serves me correctly, is in white marble, and its beauty comes entirely from the sculptor's art. Such monuments give you much better than any words of mine ample suggestions for marble treatment. I may quote such names as Nicolo Pisano and Verocchio.

Photos of some of their work I have brought. Note Pisano's beautiful white altar at Bologna, and Mina de Fiesole's work in Florence. They all show the sculptor as supreme. Why should not we encourage individual young sculptors more? Give them portions of your work in which they can put all the fervor and enthusiasm of young manhood. Their powers may not be ripe, but they possess a verve and intensity that may have forever fled when in later years the imagination is less enthusiastic and the pulses slower. I am sure there are many young sculptors now wanting commissions who have been trained at the academy, and better still, in the best French schools. I maintain that the contemporary French school of sculpture is in its line equal to any school of sculpture that has ever existed, not excepting that of Phidias or that of the Italian Renaissance of the fifteenth and sixteenth centuries. I believe history will confirm this. Why not give these men an opportunity, and help on the movement to found a truly English school of sculpture, rather than give all such work to trading firms of carvers, who will do you any number of superficial feet, properly priced and scheduled, and in the bills of quantities, of any style you please, from prehistoric to Victorian Gothic? Of course, this is our British way of founding a great school.

There is one method of treatment that appeals to me very strongly, and that is the application of colored metals to marble, more especially bronze and copper. I may quote as a successful example near the Wellington Memorial at St. Paul's. Another suggestion—although it is not used in combination with marble, but it nevertheless suggests what might be done in the way of bronze panels—that is, the Fawcett Memorial, by Gilbert, in the west chapel at Westminster Abbey.

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THE ST. LAWRENCE HOSPITAL FOR THE INSANE.

The St. Lawrence State Hospital at Ogdensburg, N.Y., is a center of public, professional, philanthropic, and legislative interest. Though projected in advance of the adoption of the system of State care for the insane, it was opened at a time to make it come under close observation in relation to the question of State care, and the friends of this departure from the inefficient, often almost barbarous provisions of county house confinement could have no better example to point the excellence of their theories than this new and progressively planned State hospital. The members of the State Lunacy Commission and Miss Schuyler and her colleagues of the State Charities Aid Society, who fought the State care bills through the Legislature this winter and in 1890, would be repaid for all of their trouble by contrasting the condition of the inmates of the St. Lawrence State Hospital with the state they were in under their former custodians, the county officers of the northern New York counties. At the best, even when these officials realized the responsibility of their charge and were actuated by humane impulses, the county houses offered no chance of remedial treatment. Custody and maintenance, the former mainly a reliance on force, the later often of scant provision, were the sum total of what was deemed necessary for the lunatics. In their new environment they find everything as different in accommodations and treatment as the word hospital in the title of the institution is different in sound and significance from the hope-dispelling, soul-chilling names of "asylum," "mad house," and "bedlam" formerly given to all retreats for the mentally afflicted. They find, and it is an encouraging feature of the plan that so many of them quickly see and appreciate it, that they are considered as sufferers from disease and not from demoniacal possession. The remarkable range of classification provided for, the adaptability of construction to the different classifications, the reliance on occupation, the dependence on treatment, and the subordination of the custodial feature, except where a wise conservatism demands its retention, are apparent alike to inmates and visitors.

This hospital is complete as to plans, and as to the power plant, drainage, and subway construction necessary for the 1,500 patients, that the legislature has provided for in its law establishing the institution. Buildings are already finished and occupied that accommodate 200 inmates, and the contractors have nearly finished part of the central group that will bring that number up to nearly 1,300. The appropriation asked for this year by the managers will be scaled down considerably by Mr. McClelland, the very economical chairman of the Ways and Means Committee of the Democratic Assembly. But, unless he has miscalculated, there will be money enough to carry on the work of construction to advantage for the year. An appropriation sufficient to complete the buildings at once was thought by many to be the wisest economy, but big figures in an appropriation bill have very little chance this year. The bill establishing the State Hospital district and providing for the building of the institution fixed the per capita cost of construction, including the purchase of land, at $1,150, and the plans have been made on that basis for 1,500 patients. But if the needs of the district should require it, the capacity could be increased by an almost indefinite extension of the system of outlying colony groups at a very small per capita cost, as the central group is by far the most expensive in construction.

The administration group in part, and one outlying group, with the general kitchen, bakery, workshop, laundry, employes' dwelling house, power house, and pumping station, are already erected, and have added a feature of architectural beauty to Point Airy. This point, of itself of picturesque and romantic beauty, juts into the St. Lawrence River at the head of the Galoup Rapids, three miles below Ogdensburg. It is a part of the hospital farm of 950 acres, which includes woodland, meadow, farm land, and a market garden tract of the $100 an acre grade. The location of the institution in these particulars and in reference to salubrity, sewerage facilities and abundance and excellence of water supply, is wonderfully advantageous.

In planning the hospital Dr. P.M. Wise, who has since become its medical superintendent, aimed to take the utmost advantage of the scenic and hygienic capabilities of the site, and to improve on all previous combinations of the two general divisions of a mixed asylum—a hospital department for the concentration of professional treatment, and a maintenance department for the separate care of the chronic insane. He was anxious to secure as much as possible of the compactness and ease of administration of the linear plan of construction, with wings on either side of the executive building of long corridors occupied as day rooms, with sleeping rooms opening out of them on both sides. But he wanted to avoid the depressing influence of this monotonous structure, as the better results of variety and increased opportunities of subdivision and classification are well recognized. He was not, however, prepared to accept wholly that abrupt departure from the linear plan known as the "cottage plan," which in some institutions has been carried to the extreme of erecting a detached building for every ward. The climate of St. Lawrence county forbade this. Her winters are as vigorous as those of her Canadian neighbors, even as her people are almost as ebullient in their politics as the vigorous warring liberals and conservatives across the river. And there are features of the linear plan that can only be left out of our asylum structure at the expense of efficiency. Other rules that he formulated from his experience were that a building for the insane should never exceed two stories in height; that fire proof construction and at least two stairways from the upper floors should be provided; that day rooms should be on the first and sleeping rooms on the second floor; that all buildings for the insane who suffer from sluggish and enfeebled circulation of the blood should be capable of being warmed to 70 deg. in the coldest weather; that ample cubic space and ventilation should be provided; and that, as far as possible, without too great increase of the cost of maintenance or sacrificing essential provisions for treatment and necessary restraint, asylums should aim to reproduce the conditions of domestic life.



State Architect Isaac G. Perry planned the St. Lawrence State Hospital buildings on ideas suggested by medical experience, with a breadth of comprehension and a technical skill in combining adaptability, utility, and beauty that have accomplished wonders. The buildings are satisfactory in every particular to every one who has seen them, and even the most casual observer is impressed with the effect of beauty. This was accomplished without elaboration of material, expressive carving or finish. The ornamentation is purely structural and is obtained by a handling of the materials of construction which also yielded the largest promise of strength and durability.

The central hospital group, of which an idea is given in the cut, now consists of five buildings. The picture shows three, the center one and two of the flanking cottages on one side. They are matched on the other side. The central or administration building is a three story structure of Gouverneur marble, and, like all of the stone used, a native St. Lawrence county stone. The marble's bluish gray is relieved by sparkling crystallizations, and its unwrought blocks are handled with an ornamental effect in the piers, lintels, and arches, and well set off by a simple high-pitched slate roof, with terra-cotta hiprolls, crestings, and finials. The open porches are both ornamental and useful, taking the place of piazzas. The tower is embellished with a terra-cotta frieze. All accommodations for an executive staff for the 1,500 patients may be provided in this building.

Behind it on the south is a one story building whose ground plan is the segment of a circle. It contains sun rooms, medical offices, general library, laboratory and dispensary, and the corridor connecting the reception cottages, one for women, on one side, and one for men on the other, with the administration building. As this one story structure is 171 feet by 41, the buildings known as cottages of the central group are more than nominally separated. All the advantages of segregation and congregation are combined.

The reception cottages are of pale red Potsdam sandstone. Their simple construction is pleasing. The ground plan is in the form of a cross; the angles of the projections being flanked by heavy piers between which are recessed circular bays carried up to the attic and arched over in the gables. The cross plan affords abundant light to all the rooms, and as much of the irregular outline as possible is utilized with piazzas. With still another recourse to the combination corridor plan, the observation cottages are joined to the reception cottages on each side. The other utilization of the corridor in this case is for conservatories. The observation cottages are irregular in plan and vary from each other and from the other buildings in the group. Unwrought native bluestone is the building material. These cottages contain a preponderance of single rooms, the purpose being to keep patients separate until their classification is decided upon.

The buildings planned but not yet constructed of the central group include two cottages for convalescents and two one-story retreats for noisy and disturbed patients. In both cases the plans are the most complete and progressive ever made. In the first the degree of construction is reduced to the minimum. Convalescents are to have freedom from the irritations of hospital life that often retard recovery. Great reliance is placed upon that important element in treatment, the rousing of a hopeful feeling in the mind of the patient.

The retreat wards, with accommodations in each wing for eighteen patients, show in this particular how little the old method of strict confinement is to be employed in the new institution. That proportion of the total insane population of 1,500 is regarded as all that it is necessary to sequester to prevent the disturbance of the rest. Hollow walls, sleeping room windows opening into small areas, and corridor space between the several divisions are features which make the per capita cost of the construction comparatively large for these two cottages, but which, it is believed, will prove to be wise ones.

All of these buildings are as complete from a hospital standpoint as can possibly be devised. Outer walls wind and moisture proof, and inner walls of brick, with an absolutely protected air space between, insure strength and warmth. An interior wall finish of the hardest and most non-absorbent materials known for such uses is a valuable hygienic provision, and both safety and salubrity are further conserved by an absence of any hollow spaces between floors and ceilings, or in stud partitions. No vermin retreats, no harbors for rodents, no channels for flame exist. Heating is accomplished by indirect radiation with the steam supply from the power house, but there are many open fireplaces to add to the complete stack and flue system of ventilation.

Attached to the central group and completed are the kitchen building, the laundry building and a dwelling house for employes, which are so disposed in the rear of the group as to make a courtyard of value for the resort of patients, as the main buildings protect and shelter it. These buildings are ample for their work when the institution's full capacity is attained. The kitchen building is a particularly interesting one. All of the cooking is to be done there, and a system of subways, with tracks on which food cars are run, connects it with all of the groups. An idea of the magnitude of kitchen plans for such an institution may be got from one single fact. The pantry is a lofty room, 20x32 feet.

The calculation that 80 per cent. of the insane of the district would be in the chronic stages of the disease explains the provision in detached cottage groups for this proportion of the patients. A great proportion of these are feeble and helpless, requiring constant attendance night and day, but attendance that can be given cheaply and efficiently in associate day rooms, dining rooms and large dormitories. Detached group No. 1, which is completed, is an infirmary group for patients of both sexes of this class. It is chiefly one story in height, and the plan permits an abundance of sunlight and air for every room.

Detached group No. 2 is intended for 185 men of the chronic insane class, who require more than ordinary care and observation. Detached group No. 3 is composed of two-story buildings for 322 women. It has several large work-shops. Occupation is one of the main reliances of the planners of the institution as a part of the treatment there.

Detached group No. 4 is designed for both men and women, and will accommodate 150. A wholly different classification is here provided for, the actively industrious classes being intended for this group. Those who are able to do outdoor work, and for whom some diverting employment will be beneficial in making them contented and physically healthy, will live here. There is complete separation of day rooms, but the two sexes will dine together in an associate hall.

An amusement hall to harmonize with the central group, and to be built adjacent to it, is planned, and will be built this year if the appropriation will permit. It is a valuable and necessary adjunct to the other provisions for the care of a population of 1,500. Accommodations for entertainments, chapel exercises, dancing and a bathing establishment are included in the plans in a way that gives great results with great economy of construction.

Probably the feature in the scheme of the St. Lawrence State Hospital of the greatest popular and professional interest is Dr. Wise's plan to have there an Americanized and improved Gheel. The original Gheel in Belgium is a colony where for many years lunatics have been sent for domiciliary care. Its inhabitants, mostly of the peasant class, have grown accustomed to the presence and care of patients with disordered minds. The system is the outgrowth of a superstition founded in the presumed miraculous cure of a lunatic whose reason was restored by the shock of the sight of the killing of a beautiful girl by her pursuing father, whose fury had been roused by her choice of a husband. A monument to this unfortunate graces Gheel, and as St. Dymphna she is supposed to be in benign control of the lunatic-sheltering colony. Some of the features of the Gheel system of care are also distinctively known as the Scotch system. There the placing of patients in family care is common. Massachusetts has also adopted it to a considerable extent. But there are many objections to family care in isolated domiciles, as practiced in Massachusetts. Special medical attention and official visits are made expensive and inconvenient. Dr. Wise plans to get all the advantages of such a mode of life for patients whose condition retrogrades under institutional influence. Not the least of these advantages is that of economy in relieving the State from the per capita cost of construction for at least one-fourth of the insane of the district. He would utilize the families in the settlement which always grows up in the vicinity of a large hospital. It is composed of the households of employes, many of which are the result of marriages among the attendants and employes. On Point Airy, by the use of the buildings that were on the different plots bought by the State to make up the hospital farm, such a settlement can be easily made up. Its inhabitants would pay rent to the State. They would be particularly fit and proper persons to board and care for patients whose condition was suitable for that sort of a life, and the patients could have many privileges and benefits not possible in the hospital. Point Airy's little Gheel on such a plan would be a most interesting and valuable extension of the beneficent rule of St. Dymphna.

The St. Lawrence State Hospital was built and is operated under the supervision of a board of managers, whose fidelity to it is described as phenomenal by the people of Ogdensburg. The members of the executive committee, Chairman William L. Proctor, Secretary A.E. Smith, John Hannan and George Hall, especially Mr. Proctor and Mr. Smith, have given as much time and attention to it as most men would to a matter in which they had a business interest. The result has been a performance of contract obligations in which the State got its money's worth. The people of Ogdensburg, too, have taken a great interest in the institution. Such men as Mayor Edgar A. Newell, ex-Collector of the Port of New York Daniel Magone, Postmaster A.A. Smith, Assemblyman George R. Malby, and his predecessor, Gen. N.M. Curtis, who was the legislative father of the hospital scheme; Frank Tallman and Amasa Thornton take as much pride in the institution that the State has set down at the gates of their city as they do in their cherished and admired city hall, which combines a tidy little opera house with the quarters necessary for all public and department uses.

The executive staff of the hospital consists of Dr. P.M. Wise, medical superintendent; Dr. J. Montgomery Mosher, assistant: Dr. J.A. Barnette and Steward W.C. Hall.—N.Y. Sun.

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THE ELECTRICAL PURIFICATION OF SEWAGE AND CONTAMINATED WATER.

[Footnote: Recently read before the Chemical Society, London. From the Journal of the Society.]

By WM. WEBSTER.

The term sewage many years ago was rightly applied to the excremental refuse of towns, but it is a most difficult matter to define the liquid that teems into our rivers under the name of sewage to-day; in most towns "chemical refuse" is the best name for the complex fluid running from the sewers.

It is now more than ten years since I first commenced a series of experiments with a view of thoroughly testing various methods of purifying sewage and water contaminated with putrefying organic matter. It was while investigating the action of iron salts upon organic matter in solution and splitting up the chlorides present by means of electrolysis, that I first became aware of the importance of precipitating the soluble organic matter in such manner that no chemical solution should take the place of the precipitated organic matter. If chemical matter is substituted for the organic compounds, the cure is worse than the disease, as the resulting solution in most cases sets up after precipitation in the river into which it flows.

My first electrolytical experiments were conducted with non-oxidizable plates of platinum and carbon, but the cost of the first and the impossibility of obtaining carbon plates that would stand long-continued action of nascent chlorine and oxygen made it desirable that some modification should be tried. I next tried the effect of electrolytic action when iron salts were present, but did not think of using iron electrodes until after trying aluminum. I found that the action of non-oxidizable electrodes was most efficacious after the temperature of the fluid acted upon rose 4 deg. or 5 deg.; but the cost of working made it impossible on a large scale.

After a long series of experiments, iron plates were used as electrodes, with remarkable results, for the compounds of iron formed not only deodorized the samples of sewage acted on, but produced complete precipitation of the matters in suspension, and also of the soluble organic matter; the resulting effluents remaining perfectly free from putrefaction. The first part of the process is well illustrated by the small experiments now shown; the organic matter in suspension and in solution separates into flocculent particles, which rise to the top of the liquid and remain until the bubbles of hydrogen which have carried them up escape, when the solid matter will precipitate. In the arrangement adopted on a working scale, the separated particles precipitate readily. As an illustration of the action upon organic matter in solution I take a small quantity of dye, mix it with water, and placing the connected iron electrodes in the mixture, the dye in solution separates into flocculent particles. The electrolytical action is of course easily understood, but the chemical changes that take place need an explanation. At the positive pole, hypochlorite of iron seems to be formed at first, but this is quickly changed into a protochloride, and as at the negative pole an alkaline reaction takes place, the iron salt is precipitated in the form of the ferrous hydrated oxide, together with the organic matters in suspension and solution. Owing to the carbonates that are always present in sewage, ferrous carbonate is also formed.

The success of these laboratory experiments led me to a trial of the process on a larger scale, for hitherto only a gallon at any one time had been treated.

Small brick tanks were erected at my wharf at Peckham and iron electrodes fitted to them.

Wrought iron plates were fixed about an inch apart, and connected in parallel in the tanks, forming one big cell. Sewage to the amount of about 200 gallons was run into the electrode tank and then treated, the results being so satisfactory that larger works were erected, when a supply of sewage equal to 20,000 gallons an hour could be obtained.

After a number of experiments had been carried out it was decided to run the sewage as rapidly as possible through electrodes, six cells or two rows in series fixed in a long channel or shoot, for experience showed that the motion of the liquid acted on reduced the back E.M.F. and hastened the formation of the precipitate.

A channel is kept at the bottom of the electrodes for the silt to collect, with a culvert at side to flush it into, so as to prevent any block occurring; the advantage of this is obvious. The plates in each section may be from half an inch to an inch thick, and can be of any length up to 6 ft. It may possibly be objected that a large number of plates is required. This may be so, but the larger the number of plates, the less the engine power required, and the longer they last. In each section the electrodes are in parallel, and any one section is in series with the other, the arrangement being exactly like that of a series of primary battery cells.

By actual experience I have been able to prove that at least 25 sections of electrodes should be in series and across any one of these sections the potential difference need not be greater than 1.8 volts, the current being of any desired amount, according to the surface of plates used.

The electrical measurements taken by Dr. John Hopkinson during these experiments for the Electrical Purification Association, to whom I had sold my patents, entirely corroborated my contentions as to E.H.P. used, and agreed with the measurements of the managing electrician, Mr. Octavius March.

The process was then thoroughly investigated by Sir Henry Roscoe, who had control of the works for one month. He reports as follows:

"The reduction of organic matter in solution is the crucial test of the value of a purifying agent, for unless the organic matter is reduced, the effluent will putrefy and rapidly become offensive.

"I have not observed in any of the unfiltered effluents from this process which I have examined any signs of putrefaction, but, on the contrary, a tendency to oxidize. The absence of sulphureted hydrogen in samples of unfiltered effluent, which have been kept for about six weeks in stoppered bottles, is also a fact of importance. The settled sewage was not in this condition, as it rapidly underwent putrefaction, even in contact with air, in two or three days.

"The results of this chemical investigation show that the chief advantages of this system of putrefaction are:

"First.—The active agent, hydrated ferrous oxide, is prepared within the sewage itself as a flocculent precipitate. (It is scarcely necessary to add that the inorganic salts in solution are not increased, as in the case where chemicals in solution are added to the sewage.) Not only does it act as a mechanical precipitant, but it possesses the property of combining chemically with some of the soluble organic matter and carrying it down in an insoluble form.

"Second.—Hydrated ferrous oxide is a deodorizer.

"Third.—By this process the soluble organic matter is reduced to a condition favorable to the further and complete purification by natural agencies.

"Fourth.—The effluent is not liable to secondary putrefaction."

Mr. Alfred E. Fletcher also investigated the process subsequently, and reports as follows:

"The treatment causes a reduction in the oxidizable matter in the sewage, varying from 60 to 80 per cent. The practical result of the process is a very rapid and complete clarification of the sewage, which enables the sludge to separate freely.

"It was noticed that while the raw sewage filters very slowly, so that 500 c.c. required 96 hours to pass through a paper filter, the electrically treated sewage settled well and filtered rapidly.

"Samples of the raw sewage, having but little smell when fresh, stank strongly on the third day. The treated samples, however, had no smell originally, and remain sweet, without putrefactive change.

"In producing this result two agencies are at work, there is the action of electrolysis and the formation of a hydrated oxide of iron. It is not possible, perhaps, to define the exact action, but as the formation of an iron oxide is part of it, it seemed desirable to ascertain whether the simple addition of a salt of iron with lime sufficient to neutralize the acid of the salt would produce results similar to those attained by Webster's process.

"In order to make these experiments, samples of fresh raw sewage were taken at Crossness at intervals of one hour during the day. As much as 10 grains of different salts of iron were added per gallon, plus 15.7 grains of lime in some cases and 125 grains of lime in another, and the treated sewage was allowed to settle twenty-four hours; the results obtained were not nearly as good as the electrical method."

During the present year a very searching investigation of the merits of various processes of sewage treatment has been made by the corporation of Salford; among others of my electrical process. As the matter is at present under discussion by the council, I am not in a position to give extracts from the reports of the engineers and chemists under whose supervision and control the work was done, but I may go so far as to say that the results of my system of electrical treatment have proved its efficiency and applicability to sewages of even such a foul nature as that of Salford and Pendleton. The system was controlled continuously for the corporation by Mr. A. Jacob, B.A., C.E., the borough engineer; Mr. J. Carter Bell, F.I.C., etc., county analyst; Messrs John Newton & Sons, engineers, Manchester; Mr. Giles, of Messrs. Mather & Pratt, electrical engineers, Manchester; Dr. Charles A. Burghardt, lecturer in mineralogy at Owens College.

I would also refer you to a paper recently read before the Manchester Section of this Society by Mr Carter Bell, the borough analyst for Salford, in whose remarks Dr. Burghardt, an independent authority, permits me to add that he concurs. He cannot give details until his report has gone in, which will be very shortly.

Mr. Carter Bell's report has gone in, and although he is precluded also from giving full details, he has kindly put at my disposal samples sealed by him of the effluents produced by the electrical treatment, which I now submit, together with the analyses in the table.

The samples are taken at random.

Whether the process will or will not be adopted by the Salford authorities I am of course unable to say, but I think I may safely say that the electrical process has now absolutely proved its case in regard to the solution of the sewage problem. It is simple, efficient and, I am sure, more economical than any other known process where duration is taken into account.

In regard to the Salford trials it may be interesting to give the following particulars:

Parts in 100,000. May 15. June 7. June 30. July 25. Not filtered. Total solids. 109 125 141 132 Loss on ignition. 33 21 29 23 Chlorine. 32 44 42 43 Oxygen required for 15 minutes. 2.56 0.76 0.27 0.79 Oxygen required for three hours. 4.27 0.79 0.50 1.00 Free ammonia. 2.20 0.88 0.50 0.92 Albuminoid am- monia. 0.32 0.17 0.092 0.19

The electrical shoot was built in brick and contained 28 cells arranged in series.

Each cell contained 13 cast iron plates 4 in. x 2 ft. 8 in. x 1/2 in. thick connected in parallel.

The available electrode surface in each cell was 256 sq. ft.

The ampere hour treatment required for Salford was found to be about 0.37 ampere hours per gallon, and the I.H.P. per million gallons based on these figures would be 37.

NOTE.—In estimating for the plant necessary for treating the whole of the Salford sewage, a margin was allowed on above figures. The A.H.T. was taken at 0.4 and the I.H.P. per million at 39 to 39.5.

Mr. Octavius March, electrical engineer, who has followed the process from the commencement, and who superintended the electrical details both at Crossness and Salford, will give you on the blackboard a rough sketch of the above trial plant.

The Salford tanks are admirably adapted to the application of the electrical or in fact any process of precipitation. They are 12 in number, and it is proposed to take two end tanks for the electrical channels, in which the iron electrodes would be placed.

The total I.H.P. required for treating the whole of the Salford and Pendleton sewage, taken at 10,000,000 gallons per 24 hours, is calculated at 400 I.H.P., based on the actual work done during the trial. The electrical plant would consist of four engines and dynamos, any three of which could do the whole work, and three boilers, each of 200 I.H.P.

The total cost of plant, including alterations, is estimated at L16,000, to which must be added the cost of about 5,000 tons of iron plates—ordinary cast iron—at say L4 per ton. These plates would last for several years.

If filtration were required, there would be an extra expenditure for this, but it will be remarked that as the treated sewage is practically purified when it leaves the electrical channels, these filters would be only required for complete clarification, which for most places would not be a necessity.

The filtering material used could be gradually prepared from the sludge obtained after electrical treatment, unless it could be more profitably sold as a manure, and I am not a believer in the value of sewage sludge in large quantities. This sludge, a waste product, is converted into magnetic oxide of iron, of which I have here two small samples. This magnetic oxide is a good filtering material, but, like every other filtering material, it would of course require renewal. There would, however, always be a supply of the waste product—sewage sludge—on the spot, and the spent magnetic oxide recarbonized could be used indefinitely.

The annual cost for dealing with the Salford sewage is estimated at in round figures L2,500 for coal, labor, maintenance of engines, boilers and dynamos. To this must be added the consumption of iron and its replacement, which would have to be written off capital expenditure.

If a colorless effluent were required, absolutely free from suspended matter, the additional cost is estimated at from L1,200 to L1,500.

* * * * *



LAVENDER AND ITS VARIETIES.

By J. CH. SAWER, F.L.S.

Lavender—technically Lavandula. This name is generally considered to be derived from the word lavando, gerund of the verb lavare, "to wash" or "to bathe," and to originate from the ancient Roman custom of perfuming baths with the flowers of this plant.

The general aspect of the various species which compose this genus of labiate plants, although presenting very characteristic differences, merges gradually from one species to another; all are, in their native habitat, small ligneous undershrubs of from one to two feet in height, with a thin bark, which detaches itself in scales; the leaves are linear, persistent, and covered with numerous hairs, which give the plant a hoary appearance.

The flowers, which are produced on the young shoots, approximate into terminal simple spikes, which are, in vigorous young plants, branched at the base and usually naked under the spikes.

As a rule, lavender is a native of the countries bordering on the great basin of the Mediterranean—at least eight out of twelve species are there found to be indigenous on mountain slopes.

The most commonly known species are L. vera, L. spica and L staechas. Commercially the L. vera is the most valuable by reason of the superior delicacy of its perfume; it is found on the sterile hills and stony declivities at the foot of the Alps of Provence, the lower Alps of Dauphine and Cevannes (growing in some places at an altitude of 4,500 feet above the sea level), also northward, in exposed situations, as far as Monton, near Lyons, but not beyond the 46th degree of latitude; in Piedmont as far as Tarantaise, and in Switzerland, in Lower Vallais, near Nyon, in the canton of Vaud, and at Vuilly. It has been gathered between Nice and Cosni, in the neighborhood of Limone, on the elevated slopes of the mountains of western Liguria, and in Etruria on hills near the sea. The L. spica, which is the only species besides L. vera hardy in this country, was formerly considered only a variety of L. vera; it is distinguished by its lower habit, much whiter color, the leaves more congested at the base of the branches, the spikes denser and shorter, the floral leaves lanceolate or linear, and the presence of linear and subulate bractes.