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THE DENSITY AND PRESSURE OF DETONATING GAS MIXTURES.

MM. Berthelot and Vielle have recently been studying the influence of the density of detonating gaseous mixtures upon the pressure developed. The measure of pressure developed by the same gaseous system, taken under two initial states of different density to which the same quantity of heat is communicated, is an important matter in thermodynamics. If the pressures vary in the same ratio as the densities, we may conclude, independently of all special hypotheses on the laws of gases, first, that the specific heat of the system is independent of its density (that is to say, of its initial pressure), and depends only on the absolute temperature, whatever that may mean; and secondly, that the relative variation of the pressure at constant volume, produced by the introduction of a determinate quantity of heat, is also independent of the pressure, and a function only of the temperature. Lastly, the pressure itself will vary proportionally with the absolute temperature, as defined by the theory of a perfect gas, and will serve to determine it. MM. Berthelot and Vielle operated with a bomb, at first kept at ordinary temperatures in the air, and afterward heated in an oil bath to 153 deg. Cent. They also employed isomeric mixtures of the gases; methylic ether, cyanogen, hydrogen, acetylene, and other gases were experimented upon, and the general conclusions are as follows: 1. The same quantity of heat being furnished to a gaseous system, the pressure of the system varies proportionally to the density of the system. 2. The specific heat of the gas is sensibly independent of the density as well toward very high temperatures as about deg. Cent. This is all true for densities near to those that the gas possesses cold under normal pressure, and which varied in the experiment to double the original value. 3. The pressure increases with the quantity of heat furnished to the same system. 4. The apparent specific heat increases parallel with this quantity of heat. These conclusions are independent of all hypotheses on the nature and laws of gases, and were simply drawn from the experiments in question.

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TURKISH BATHS FOR HORSES.

The Turkish bath has become an established institution in this country; men of all classes now use it for sanitary as well as remedial purposes. Athletes of various descriptions find it invaluable in "training," and all the distinguished jockeys and light weights keep themselves in condition by its use.

It was thought probable that what was good for man might also be good for the horse, and the fact has been proved. Messrs. Pickford, the eminent carriers, in their hospital for horses at Finchley, have had a bath in operation over eleven years, and find the horses derive great benefit from its use. The bath is put in operation three days a week, and is administered to over twenty horses in this time. The value of the bath having been thus proved, it is rather strange that it has not been more generally adopted by the large carrying firms. However, the Great Northern Railway Company at their new hospital for horses at Totteridge, are erecting a very complete Turkish bath. It consists of three rooms. First, a large wash room or grooming room, from which is entered the first hot room, or tepidarium, from 140 deg. to 150 deg. Fahr.; from this room, the horse, after being thoroughly acclimated, can, if necessary, pass to the hottest room, or calidarium, from 160 deg. to 170 deg. Fahr., and without any turning round can pass on into the grooming and washing room again. This last room is slightly heated from the two other rooms, and in each are stocks in which the animal can he fastened if required. The heating is done most economically by Constantine's convoluted stove, and thorough ventilation is secured from the large volume of hot air constantly supplied, which passes through the baths, and as it becomes vitiated is drawn off by specially designed outlets. The wash room is supplied with hot and cold water, which can, of course, be mixed to any required temperature.—Building News.



+ -+ + -+ -_ -_ _ -+ FOUL AIR FOUL AIR FOUL AIR ============== / / / / 1ST HOT ROOM / / / / ============== / =======+ / CURTAIN WASHING ROOM +=========================== = =======+ ============== 2ND HOT ROOM FRESH / AIR ============== == +====== WARM FOUL AIR FOUL AIR AIR + -+ -_ +===+ -_ + == + _ _ -+ ============ S T O K E R Y + - + -+

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MIRYACHIT, A NEWLY DESCRIBED DISEASE OF THE NERVOUS SYSTEM, AND ITS ANALOGUES.[1]

[Footnote 1: Read before the New York Neurological Society, February 5, 1884.]

By WILLIAM A. HAMMOND, M.D., Surgeon-General, U.S. Army (Retired List); Professor of Diseases of the Mind and Nervous System in the New York Post-Graduate Medical School and Hospital.

In a very interesting account of a journey from the Pacific Ocean through Asia to the United States, by Lieutenant B.H. Buckingham and Ensigns George C. Foulk and Walter McLean,[2] United States navy, I find an affection of the nervous system described which, on account of its remarkable characteristics, as well as by reason of certain known analogies, I think should be brought to the special notice of the medical profession. I quote from the work referred to, the following account of this disease. The party is on the Ussuri River not far from its junction with the Amur in Eastern Siberia: "While we were walking on the bank here we observed our messmate, the captain of the general staff (of the Russian army), approach the steward of the boat suddenly, and, without any apparent reason or remark, clap his hands before his face; instantly the steward clapped his hands in the same manner, put on an angry look, and passed on. The incident was somewhat curious, as it involved a degree of familiarity with the steward hardly to have been expected. After this we observed a number of queer performances of the steward, and finally comprehended the situation. It seemed that he was afflicted with a peculiar mental or nervous disease, which forced him to imitate everything suddenly presented to his senses. Thus, when the captain slapped the paddle-box suddenly in the presence of the steward, the latter instantly gave it a similar thump; or, if any noise were made suddenly, he seemed compelled against his will to imitate it instantly, and with remarkable accuracy. To annoy him, some of the passengers imitated pigs grunting, or called out absurd names; others clapped their hands and shouted, jumped, or threw their hats on the deck suddenly, and the poor steward, suddenly startled, would echo them all precisely, and sometimes several consecutively. Frequently he would expostulate, begging people not to startle him, and again would grow furiously angry, but even in the midst of his passion he would helplessly imitate some ridiculous shout or motion directed at him by his pitiless tormenters. Frequently he shut himself up in his pantry, which was without windows, and locked the door, but even there he could be heard answering the grunts, shouts, or pounds on the bulkhead outside. He was a man of middle age, fair physique, rather intelligent in facial expression, and without the slightest indication in appearance of his disability. As we descended the bank to go on board the steamer, some one gave a loud shout and threw his cap on the ground; looking about for the steward, for the shout was evidently made for his benefit, we saw him violently throw his cap, with a shout, into a chicken-coop, into which he was about to put the result of his foraging expedition among the houses of the stanitza.

[Footnote 2: "Observations upon the Korean Coast, Japanese-Korean Ports, and Siberia, made during a journey from the Asiatic Station to the United States, through Siberia to Europe, June 3 to September 8, 1882." Published by the United States Navy Department, Washington, 1883, pp. 51.]

"We afterward witnessed an incident which illustrated the extent of his disability. The captain of the steamer, running up to him, suddenly clapping his hands at the same time, accidentally slipped and fell hard on the deck; without having been touched by the captain, the steward instantly clapped his bands and shouted, and then, in powerless imitation, he too fell as hard and almost precisely in the same manner and position as the captain. In speaking of the steward's disorder, the captain of the general staff stated that it was not uncommon in Siberia; that he had seen a number of cases of it, and that it was commonest about Yakutsk, where the winter cold is extreme. Both sexes were subject to it, but men much less than women. It was known to Russians by the name of 'miryachit'".

So far as I am aware—and I have looked carefully through several books of travel in Siberia—no account of this curious disease has been hitherto published.

The description given by the naval officers at once, however, brings to mind the remarks made by the late Dr. George M. Beard, before the meeting of the American Neurological Association in 1880, relative to the "Jumpers" or "Jumping Frenchmen" of Maine and northern New Hampshire.[3]

[Footnote 3: "Journal of Nervous and Mental Diseases," vol. vii., 1880, p. 487.]

In June, 1880, Dr. Beard visited Moosehead Lake, found the "Jumpers," and experimented with them. He ascertained that whatever order was given them was at once obeyed. Thus, one of the jumpers who was sitting in a chair with a knife in his hand was told to throw it, and he threw it quickly, so that it stuck in a beam opposite; at the same time he repeated the order to throw it with a cry of alarm not unlike that of hysteria or epilepsy. He also threw away his pipe, which he was filling with tobacco, when he was slapped upon the shoulder. Two jumpers standing near each other were told to strike, and they struck each other very forcibly. One jumper, when standing by a window, was suddenly commanded by a person on the other side of the window to jump, and he jumped up half a foot from the floor, repeating the order. When the commands are uttered in a quick, loud voice, the jumper repeats the order. When told to strike he strikes, when told to throw he throws whatever he may happen to have in his hand. Dr. Beard tried this power of repetition with the first part of the first line of Virgil's "AEneid" and the first part of the first line of Homer's "Iliad," and out-of-the-way words of the English language with which the jumper could not be familiar, and he repeated or echoed the sound of the word as it came to him in a quick, sharp voice, at the same time he jumped, or struck, or threw, or raised his shoulders, or made some other violent muscular motion. They could not help repeating the word or sound that came from the person that ordered them, any more than they could help striking, dropping, throwing, jumping, or starting; all of these phenomena were indeed but parts of the general condition known as jumping. It was not necessary that the sound should come from a human being; any sudden or unexpected noise, as the explosion of a gun or pistol, the falling of a window, or the slamming of a door—provided it was unexpected and loud enough—would cause these jumpers to exhibit some one or all of these phenomena. One of these jumpers came very near cutting his throat, while shaving, on hearing a door slam. They had been known to strike their fists against a red-hot stove, to jump into the fire and into water. They could not help striking their best friend if near them when ordered. The noise of a steam whistle was especially obnoxious to them. One of these jumpers, when taking some bromide of sodium in a tumbler, was told to throw it, and he dashed the tumbler upon the floor. It was dangerous to startle them in any way when they had an ax or an knife in their hands. All of the jumpers agreed that it tired them to be jumped, and they dreaded it, but they were constantly annoyed by their companions.

From this description it will at once, I think, be perceived that there are striking analogies between "miryachit" and this disorder of the "Jumping Frenchmen" of Maine. Indeed, it appears to me that, if the two affections were carefully studied, it would be found that they were identical, or that, at any rate, the phenomena of the one could readily be developed into those of the others. It is not stated that the subjects of miryachit do what they are told to do. They require an example to reach their brains through the sense of sight or that of hearing, whereas the "Jumpers" do not apparently perform an act which is executed before them, but they require a command. It seems, however, that a "Jumper" starts whenever any sudden noise reaches his ears.

In both classes of cases a suggestion of some kind is required, and then the act takes place independently of the will. There is another analogous condition known by the Germans as Schlaftrunkenheit, and to English and American neurologists as somnolentia, or sleep-drunkenness. In this state an individual, on being suddenly awakened, commits some incongruous act of violence, ofttimes a murder. Sometimes this appears to be excited by a dream, but in others no such cause could be discovered.

Thus, a sentry fell asleep during his watch, and, being suddenly aroused by the officer in command, attacked the latter with his sword, and would have killed him but for the interposition of the bystanders. The result of the medical examination was that the act was involuntary, being the result of a violent confusion of mind consequent upon the sudden awaking from a profound sleep. Other cases are cited by Wharton and Stille in their work on medical jurisprudence, by Hoffbauer, and by myself in "Sleep and its Derangements."

The following cases among others have occurred in my own experience:

A gentleman was roused one night by his wife, who heard the street-door bell ring. He got up, and, without paying attention to what she said, dragged the sheets off of the bed, tore them hurriedly into strips, and proceeded to tie the pieces together. She finally succeeded in bringing him to himself, when he said he had thought the house was on fire, and he was providing means for their escape. He did not recollect having had any dream of the kind, but was under the impression that the idea had occurred to him at the instant of his awaking.

Another was suddenly aroused from a sound sleep by the slamming of a window-shutter by the wind. He sprang instantly from his bed, and, seizing a chair that was near, hurled it with all his strength against the window. The noise of the breaking of glass fully awakened him. He explained that he imagined some one was trying to get into the room and had let his pistol fall on the floor, thereby producing the noise which had startled him.

In another case a man dreamed that he heard a voice telling him to jump out of the window. He at once arose, threw open the sash, and jumped to the ground below, fortunately only a distance of about ten feet, so that he was not injured beyond receiving a violent shock. Such a case as this appears to me to be very similar to those described by Dr. Beard in all its essential aspects.

A few years ago I had a gentleman under my charge who would attempt to execute any order given him while he was asleep by a person whispering into his ear. Thus, if told in this way to shout, he shouted as loud as he could; if ordered to get up, he at once jumped from the bed; if directed to repeat certain words, he said them, and so on.

I am not able to give any certain explanation of the phenomena of miryachit or of the "Jumpers," or of certain of those cases of sleep-drunkenness which seem to be of like character. But they all appear to be due to the fact a motor impulse is excited by perceptions without the necessary concurrence of the volition of the individual to cause the discharge. They are, therefore, analogous to reflex actions, and especially to certain epileptic paroxysms due to reflex irritations. It would seem as though the nerve cells were very much in the condition of a package of dynamite or nitro glycerin, in which a very slight impression is sufficient to effect a discharge of nerve force. They differ, however, from the epileptic paroxysm in the fact that the discharge is consonant with the perception—which is in these cases an irritation—and is hence an apparently logical act, whereas in epilepsy the discharge is more violent, is illogical, and does not cease with the cessation of the irritation.

Certainly the whole subject is of sufficient importance to demand the careful study of competent observers.

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THE GUM DISEASE IN TREES.[1]

[Footnote 1: Communicated to the Medical Times by Sir James Paget.]

An essay by Dr. Beijerinck, on the contagion of the gum disease in plants, lately published by the Royal Academy of Sciences at Amsterdam, contains some useful facts. The gum disease (gummosis, gum-flux) is only too well known to all who grow peaches, apricots, plums, cherries, or other stone fruits. A similar disease produces gum arabic, gum tragacanth, and probably many resins and gum resins. It shows itself openly in the exudation of thick and sticky or hard and dry lumps of gum, which cling on branches of any of these trees where they have been cracked or wounded through the bark. Dr. Beijerinck was induced to make experimental inoculations of the gum disease by suspicions that, like some others observed in plants, it was due to bacteria. He ascertained that it is in a high degree contagious, and can easily be produced by inserting the gum under the edge of a wound through the bark of any of the trees above named. The observation that heated or long boiled pieces of gum lose their contagious property made it most probable that a living organism was concerned in the contagions; and he then found that only those pieces of the gum conveyed contagion in which, whether with or without bacteria, there were spores of a relatively highly organized fungus, belonging to the class of Ascomycetes; and that these spores, inserted by themselves under the bark, produced the same pathological changes as did the pieces of gum. The fungus thus detected, was examined by Professor Oudemans, who ascertained it to be a new species of Coryneum, and has named it Coryneum Beijerincki. The inoculation experiments are best made by means of incisions through the bark of young branches of healthy peach trees or cherry trees, and by slightly raising the cut edge of the bark and putting under it little bits of gum from a diseased tree of the same kind. In nearly every instance these wounds become the seats of acute gum disease, while similar wounds in the same or other branches of the same tree, into which no gum is inserted, remain healthy, unless, by chance, gum be washed into them during rain. The inoculation fails only when the inserted pieces of gum contain no Coryneum. By similar inoculations similar diseases can be produced in plum, almond, and apricot trees, and with the gum of any one of these trees any other can be infected; but of many other substances which Beijerinck tried, not one produced any similar disease. The inoculation with the gum is commonly followed by the death of more or less of the adjacent structures; first of the bark, then of the wood. Small branches or leaf stalks thus infected in winter, or in many places at the same time, may be completely killed; but, in the more instructive experiments the first symptom of the gum disease is the appearance of a beautiful red color around the wound. It comes out in spots like those which often appear spontaneously on the green young branches of peach trees that have the gum disease; and in these spots it is usual to find Coryneum stromata or mycelium filaments. The color is due to the formation of a red pigment in one or more of the layers of the cells of the bark. But in its further progress the disease extends beyond the parts at which the Coryneum or any structures derived from it can be found; and this extension, Beijerinck believes, is due to the production of a fluid of the nature of a ferment, produced by the Coryneum, and penetrating the adjacent structures. This, acting on the cell walls, the starch granules, and other constituents of the cells, transforms them into gum, and even changes into gum the Coryneum itself, reminding the observer of the self-digestion of a stomach.

In the cells of the cambium, the same fluid penetrating unites with the protoplasm, and so alters it that the cells produced from it form, not good normal wood, but a morbid parenchymatous structure. The cells of this parenchyma, well known among the features of gum disease, are cubical or polyhedral, thin walled, and rich in protoplasm. This, in its turn, is transformed into gum, such as fills the gum channels and other cavities found in wood, and sometimes regarded as gum glands. And from this also the new ferment fluid constantly produced, and tracking along the tissues of the branches, conveys the Coryneum infection beyond the places in which its mycelium can be found.

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DRINKSTONE PARK.

Drinkstone has long been distinguished on account of the successful cultivation of remarkable plants. It lies some eight miles southeast from Bury St. Edmund's, and is the seat of T.H. Powell, Esq. The mansion or hall is a large old-fashioned edifice, a large portion of its south front being covered by a magnificent specimen of the Magnolia grandiflora, not less than 40 feet in height, while other portions of its walls are covered with the finest varieties of climbing roses and other suitable plants. The surrounding country, although somewhat flat, is well wooded, and the soil is a rich loam upon a substratum of gravel, and is consequently admirably suited to the development of the finer kinds of coniferous and other ornamental trees and shrubs, so that the park and grounds contain a fine and well selected assortment of such plants.



Coniferous trees are sometimes considered as out of place in park scenery; this, however, does not hold good at Drinkstone, where Mr. Powell has been displayed excellent taste in the way of improving the landscape and creating a really charming effect by so skillfully blending the dressed grounds with the rich greensward of the park that it is not easy to tell where the one terminates or the other commences.

The park, which covers some 200 acres, including a fine lake over eight acres in extent, contains also various large groups or clumps of such species as the Sequoia gigantea, Taxodium sempervirens, Cedres deodora, Picea douglasii, Pinsapo, etc., interspersed with groups of ornamental deciduous trees, producing a warm and very pleasing effect at all seasons of the year. Among species which are conspicuous in the grounds are fine, well-grown examples of Araucaria imbricata, some 30 feet high; Cedrus deodara, 60 feet in height; Abies pinsapo, 40 feet; and fine specimens of Abies grandis, A. nobilis, and A. nordmanniana, etc., together with Abies albertiana or mertensiana, a fine, free-growing species; also Libocedrus gigantea, Thuiopsis borealis, Thuia lobbii, Juniperus recurva, Taxas adpressa, fine plants; with fine golden yews and equally fine examples of the various kinds of variegated hollies, etc.



Particular attention is here paid to early spring flowers. Drinkstone is also celebrated as a fruit growing establishment, more particularly as regards the grape vine; the weight and quality of the crops of grapes which are annually produced here are very remarkable.—The Gardeners' Chronicle.

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ON THE CHANGES WHICH TAKE PLACE IN THE CONVERSION OF HAY INTO ENSILAGE.

By FREDK. JAS. LLOYD, F.C.S., Lecturer on Agriculture, King's College.

The recently published number of the Royal Agricultural Society's Journal contains some information upon the subject of silage which appears to me of considerable interest to those chemists who are at present investigating the changes which take place in the conversion of grass into silage. The data[1] are, so far as I know, unique, and though the analytical work is not my own, yet it is that of an agricultural chemist, Mr. A. Smetham, of Liverpool, whose work I know from personal experience to be thoroughly careful and reliable. I have therefore no hesitation in basing my remarks upon it.

[Footnote 1: Royal Agricultural Society's Journal, vol. xx., part i., pp. 175 and 380.]

We have here for the first time an accurate account of the quantity of grass put into a silo, of the quantity of silage taken out, and of the exact composition both of the grass and resulting silage. I desire merely to place myself in the position of, so to speak, a "chemical accountant."

The ensilage has been analyzed at three depths, or rather in three layers, the first being 1 foot, the second 1 ft. to 1 ft. 6 in., and the third 1 ft. 6 in. to 2 ft. from the bottom of the silo. By doubling the figures of the bottom layer analysis, adding these to the second and third layer analysis, and dividing by 4, we obtain a fair representation of the average composition of the silage taken throughout the silo, for by so doing we obtain the average of the analyses of each 6-inch layer of silage. The results of the analyses are as follows, calculated on the dry matter. The moisture was practically the same, being 70.48 per cent, in the grass and 72.97 in the silage.

Composition of Grass and Silage (dried at 100 deg.C.).

Grass. Ensilage. Fat (ether extract) 2.80 5.38 Soluble albuminous compounds 3.06 5.98 Insoluble albuminous compounds 6.94 3.77 Mucilage, sugar, and extractives, etc. 11.65 4.98 Digestible fiber 36.24 33.37 Indigestible woody fiber 32.33 31.79 ———- ———- 93.02 85.27 Soluble mineral matters 5.24 12.62 Insoluble mineral matters 1.74 2.11 ———- ———- 100.00 100.00

The striking difference in the mineral matter of the grass and silage I will merely draw attention to; it is not due to the salt added to the silage. I may say, however, that other analysts and I myself have found similar striking differences. For instance, Prof. Kinch[2] found in grass 8.50 per cent. mineral matter, in silage 10.10 per cent., which, as be points out, is equivalent, to a "loss of about 18 per cent. of combustible constituents"—a loss which we have no proof of having taken place. In Mr. Smetham's sample the loss would have to be 50 per cent., which did not occur, and in fact is not possible. What is the explanation?

[Footnote 2: Journ. Chem. Society, March, 1884, p. 124.]

I am, however, considering now the organic constituents. Calculating the percentages of these in the grass and silage, we obtain the following figures:

Percentage Composition of Organic Compounds.

Grass. Ensilage. Fat (ether extract) 3.01 6.31 Soluble albuminous compounds 8.29} {7.01 }10.75 11.43{ Insoluble " " 7.46} {4.42

Mucilage, sugar, and extractives 12.52 5.84 Digestible fiber 38.96 39.14 Indigestible woody fiber 34.76 37.28 ———- ———- 100.00 100.00

The difference in the total nitrogen in the grass and silage is equal to 0.68 per cent. of albuminoids. Practically it is a matter of impossibility that the nitrogen could have increased in the silo, and it will be a very safe premise upon which to base any further calculations that the total amount of nitrogen in the silage was identical with that in the grass. There may have been a loss, but that is not yet proved. Arguing then upon the first hypothesis, it is evident that 100 parts of the organic matters of silage represent more than 100 parts of the organic matter of grass, and by the equation we obtain 10.75:11.43 :: 100:106 approximately. If now we calculate the composition of 106 parts organic matter of grass, it will represent exactly the organic matter which has gone to form 100 parts of that present in silage.

The following table gives these results, and also the loss or gain in the various constitutents arising from the conversion into silage:

Organic Matter.

In 106 pts. In 100 pts. Loss or Grass. Silage. Gain.

Fat (ether extract) 3.19 6.31 +3.12 Soluble albuminous compounds 3.49 7.01 +3.52 Insoluble " " 7.91 4.42 -3.49 Mucilage 13.27 5.84 -7.43 Digestible Fiber 41.30 39.14 -2.16 Indigestible woody fiber 36.84 37.28 +0.44 ———- ———- 106.00 100.00

These calculations show, provided my reasoning be correct, that the chief changes which take place are in the albuminous compounds, which has already been pointed out by Professors Voelcker, Kinch, and others; and in the starch, gum, mucilage, sugar, and those numerous bodies termed extractives, which was to be expected. But they show most conclusively that the "decrease in the amount of indigestible fiber and increase in digestible" so much spoken of is, so far as our present very imperfect methods of analyzing these compounds permit us to judge, a myth; and I have not yet found any sufficient evidence to support this statement. A loss, then, of 6 parts of organic matter out of every 106 parts put into the silo has in this instance taken place, due chiefly to the decomposition of starch, sugar, and mucilage, etc. And as the grass contained 70 parts of water when put into the silo, the total loss would only be 1.7 per cent. of the total weight. This theoretical deduction was found by practical experience correct, for Mr. Smith, agent to Lord Egerton, upon whose estate this silage was made, in his report to Mr. Jenkins says the "actual weight out of the silo corresponds exactly with the weight we put into the same."

In my judgment these figures are of interest to the agricultural chemist for many reasons. First, they will clear the ground for future workers and eliminate from their researches what would have greatly complicated them—changes in the cellulose bodies.

Secondly, they are of interest because our present methods of distinguishing between and estimating digestible and indigestible fiber is most rough, and probably inaccurate, and may not in the least represent the power of an animal—say a cow—to digest these various substances; and most of us know that when a new method of analysis becomes a necessity, a new method is generally discovered. Lastly, they are of interest to the agriculturist, for they point out, I believe for the first time, the exact amount of loss which grass—or at least one sample—has undergone in conversion into silage, and also that much of the nitrogenous matter is changed, and so far as we know at present, lost its nutritive value. This, however, is only comparing silage with grass. What is wanted is to compare silage with hay—both made out of the same grass. Then, and then only, will it be possible to sum up the relative advantages or disadvantages of the two methods of preserving grass as food for cattle.—Chem. News.

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THE ILLUMINATING POWER OF ETHYLENE.

Dr. Percy Frankland has obtained results which may be thus briefly summarized: (1.) That pure ethylene, when burnt at the rate of 5 cubic feet per hour from a Referee's Argand burner, emits a light of 68.5 standard candles. (2.) That the illuminating power of equal volumes of mixtures of ethylene with either hydrogen carbonic oxide or marsh-gas is less than that of pure ethylene. (3.) That when the proportion of ethylene in such mixtures is above 63 per cent. the illuminating power of the mixture is but slightly affected by the nature of the diluent. When, on the other hand, the proportion of ethylene in such mixtures is low, the illuminating power of the mixture is considerably the highest when marsh-gas is the diluent, and the lowest when the ethylene is mixed with carbonic oxide. (4.) That if 5 cubic feet of ethylene be uniformly consumed irrespectively of the composition of the mixture, the calculated illuminating power is in every case equal to or actually greater than that of pure ethylene until a certain degree of dilution is attained. This intrinsic luminosity of ethylene remains almost constant when the latter is diluted with carbonic oxide, until the ethylene forms only 40 per cent. of the mixture, after which it rapidly diminishes to zero when the ethylene forms only 20 per cent. of the mixture. When the ethylene is diluted with hydrogen, its intrinsic luminosity rises to 81 candles when the ethylene constitutes 30 per cent. of the mixture, after which it rapidly falls to zero when the ethylene amounts to only 10 per cent. In the case of mixtures of ethylene and marsh-gas, the intrinsic luminosity of the former is augmented with increasing rapidity as the proportion of marsh gas rises, the intrinsic luminosity of ethylene, in a mixture containing 10 per cent. of the latter, being between 170 and 180 candles.

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DIFFRACTION PHENOMENA DURING TOTAL SOLAR ECLIPSES.[1]

[Footnote 1: A paper read before the American Astronomical Society, May 5, 1884.]

By G.D. Hiscox.

The reality of the sun's corona having been cast in doubt by a leading observer of the last total eclipse, who, from the erratic display observed in the spectroscope, has declared it a subjective phenomenon of diffraction, has led me to an examination and inquiry as to the bearing of an obscurely considered and heretofore only casually observed phenomenon seen to take place during total solar eclipses. This phenomenon, it seems to me, ought to account for, and will possibly satisfy, the spectroscopic conditions observed just before, during, and after totality; which has probably led to the epithet used by some leading observers—"the fickle corona." The peculiar phenomenon observed in the spectroscope, the flickering bands or lines of the solar spectrum flashing upon and across the coronal spectrum, has caused no little speculation among observers.

The diffraction or interference bands projected by the passage of a strong beam of light by a solid body, as discovered long since by Grimaldi, and investigated later by Newton, Fresnel, and Fraunhofer, are explained and illustrated in our text books; but the grand display of this phenomenon in a total solar eclipse, where the sun is the source of light and the moon the intercepting body, has as yet received but little attention from observers, and is not mentioned to my knowledge in our text books.

In the instructions issued from the United States Naval Observatory and the Signal Office at Washington for the observation of the eclipse of July 29, 1878, attention was casually directed to this phenomenon, and a few of the observers at Pike's Peak, Central City, Denver, and other places have given lucid and interesting descriptions of the flight of the diffraction bands as seen coursing over the face of the earth at the speed of the moon's shadow, at the apparent enormous velocity of thirty-three miles per minute, or fifty times the speed of a fast railway train.

From a known optical illusion derived from interference or fits of perception, as illustrated in quick moving shadows, this great speed was not realized to the eye, as the observed motion of these shadows was apparently far less rapid than their reality.

The ultra or diffraction bands outside of the shadow were distinctly seen and described by Mr. J.E. Keeler at Central City, both before and after totality. He estimates the shadow bands at 8 inches wide and 4 feet apart.

Professor E.S. Holden, also at Central City, estimated the dark bands as about 3 feet apart, and variable.

From estimates which he obtained from other observers of his party, the distances between the bands varied from 6 to l1/2 feet, but so quickly did they pass that they baffled all attempts to count even the number that passed in one second.

He observed the time of continuance of their passage from west to east as forty-eight seconds, which indicates a width of 33 miles of diffraction bands stretching outward from the edge of the shadow to the number of many thousands.

Mr. G.W. Hill, at Denver, a little to the north of the central track of the shadow, observed the infra or bands within the shadow, alluding to the fact that they must be moving at the same rate as the shadow, although their apparent motion was much slower, or like the shadows of flying clouds. He attributes the discrepancy to optical illusion.

At Virginia City the colors of the ultra bands were observed, and estimated at five seconds' duration from the edge of the shadow, which is equal to about 4 miles in width. These are known to be the strongest color bands in the diffraction spectrum, which accounts for their being generally observed.

Mr. W.H. Bush, observing at Central City, in a communication to Prof. Holden alludes to the brilliancy of the colors of these bands as seen through small clouds floating near the sun's place during totality, and of the rapid change of their rainbow colors as observed dashing across the clouds with the rapidity of thought.

All of these bands, both ultra and infra, as seen in optical experiments, are colored in reverse order, being from violet to red for each band outward and inward from the edge of the shadow.

It is very probable that the velocity of the passage of all the bands during a total eclipse very much modifies the distinctness of the colors or possibly obliterates them by optically blending so as to produce the dull white and black bands which occupied so large a portion of this grand panorama.

The phenomenon of these faint colored bands, with the observed light and dark shadows, may be attributed to one or all of the following causes:

1. A change in the direction of a small portion of the sun's light passing by the solid body of the moon, it being deflected outward by repulsion or reflection from its surface, and other portions being deflected inward after passing the body by mutual repulsion of its own elements toward a light vacuum or space devoid of the element of vibration.

2. The colored spectral bands being the direct result of the property of interference, or the want of correspondence of the wave lengths due to divergence; the same phenomenon being also observed in convergent light. This is practically illustrated in the hazy definition of the reduced aperture of telescopes, and its peculiarities shown in the spectral rings within and beyond the focus.

3. Chromatic dispersion by our atmosphere, together with selective absorption, also by our atmosphere and its vapors, have been suggested as causes in this curious and complicated phenomena.

In none of the reports descriptive of the phenomena of polarization of the corona is there the slightest allusion to the influence that the diffraction bands may possibly have in modifying or producing the various conditions of polarization observed; although these observations have been made and commented upon during the past twenty-five years.

Investigations now in progress of the modifying relation of the phenomenon of diffraction in its effect upon not only the physical aspect of the corona, but also in some strange spectroscopic anomalies that have been observed near the sun at other times than during a total solar eclipse, will, it is hoped, result in a fuller interpretation of the physical nature of one of the grandest elements of creation—light; let there be more of it.

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