which is found in fermented liquors at all times, and in quantities varying according to the situations under which these fluids have been kept.-Athenœum; abridged.

DR. URE ON THE ELASTIC FORCE AND DENSITY OF STEAM.

THE specific gravity of vapours of different substances is a subject of modern investigation, for which we are primarily indebted to M. Gay-Lussac, whose experimental process consists in measuring the volume of vapour, furnished by a given weight of liquid. Having weighed a globule of glass, like the bulb of a large thermometer, he then filled it, by heating the bulb, and plunging the point of its capillary tube in the liquid to be vapourized, repeating the heating and immersion till it was entirely full. In this state, it was slightly heated, to expel a drop of liquid from the point, which was then hermetically sealed by the flame of a blow-pipe. The bulb was next introduced into a graduated bell-jar, about a foot long, and two inches in diameter, filled with, and inverted in, mercury, contained in a cast-iron trough. This jar was enclosed within a glass cylinder, open at top and bottom, the space between the two being filled with water or oil, whose hydrostatic pressure was supported by the subjacent column of mereury. The trough or pan, with these cylinders, was placed over a little furnace, whereby it was progressively raised to any desired degree of temperature. Eventually, the liquid became sufficiently hot to generate vapour, of such tension as to burst the thin glass bulb. In the case of water, he continued to heat the apparatus till the water contained between the two cylinders entered into steady ebullition; at which instant he measured the space occupied by the steam, noting the height of the mercury in the bell above the level of the bath; by deducting which height from that of the barometer placed in the same apartment, he found the pressure of the internal vapour. He afterwards reduced by calculation the length of the volume of mercury to what it would be at the temperature of melting ice; and made the small correction due to the volume of liquid between the cylinders.

In this research, we must take care that the whole of the liquid of the bulb be reduced into vapour, otherwise we shall fall into great errors. This circumstance would occur, were more liquid introduced into the bulb than would fill the whole space in the bell-jar at the given temperature.

That the densities of vapours vary proportionally with the pressures has also been experimentally determined; or, in other words, vapours when reduced by calculation to the same standard temperature are proportional to the elastic forces. Upon this principle, the column entitled specific gravity of steam, in a certain table, has been constructed; and the column entitled number of cubic feet of steam from one pound of water, has been computed from the preceding column, and the known weight of a cubic foot of water. One volume of water at 32° produces 1694 volumes of steam, at the temperature of 212o Fahr., and a pressure of 29-912 inches of mercury. The number 0.000589, given as the specific gravity of such steam, is obtained by dividing 1000 by 1698, on the supposition that one volume of water produces 1698 volumes of ordinary steam.-Literary Gazette.

COMPRESSION OF ATMOSPHERIC AIR.

M. SAVERESSE has patented an application and method of speedily compressing atmospheric air to 150 lb. on the square inch, by means of chemical action, and very little labour. He has successfully applied his invention to the manufacture of ginger-beer and soda-water, which he can produce perfectly in 15 minutes; the material being bottled and corked up with great speed and economy at the same time by means of an apparatus attached to the machine. This consists of a globular generator, from which ascends a cylindrical tube, in which the soda-water or ginger-beer is placed; the air, by ascent, carries the latter from thence into a small vertical cylinder, where the gas is purified; and thence is carried to the large cylinder, which is placed on a swivel, in order to more perfectly mix the liquid with the gas; from whence it is bottled off. Railway Magazine.

RESPIRATION OF DETERIORATED ATMOSPHERES.

MR. C. T. COATHUPE has detailed to the British Association the results of a series of experiments on the Respiration of Deteriorated Atmospheres, which he had instituted to determine whether the injurious effects which have followed the respiration of charcoal vapours had depended on carbonic acid, as was generally thought, or on the specific agency of some other volatile product. The volatile products of the combination of charcoal he stated to be as follows:

From a number of experiments on the elimination of carbonic acid during respiration, he arrived at the following results:-that 266-666 cubic feet of atmospheric air pass through the lungs of an adult in twenty-four hours, of which 10666 are converted into carbonic acid, yielding 5.45 ounces of carbon, or 124.628 pounds annually, which will give a total of 147,070 tons of carbon as the annual product of the inhabitants of Great Britain and Ireland! The average amount of carbonic air found in atmospheric air in which animals had expired was found to be, for warm-blooded animals, 12.75 per cent., for the coldblooded animals, 13-116 per cent. When the animals were removed, on becoming comatose, the average amount of carbonic acid was found to be 10.42 per cent. On confining a taper until its extinction, the quantity of carbonic acid found was 3.046 per cent. From hence it would appear that an atmosphere that has ceased to support combustion can support animal life for some time, which Mr. Coathupe proved by direct experiment.-Athenæum.

POISONING BY CHARCOAL.

DR. GOLDING BIRD has read to the British Association a series of

"Observations on Poisoning by the Vapours of burning Charcoal." An opinion has been held, that the vapours of carbonic acid were more injurious when produced by the combustion of coal and charcoal, than from any other source, on account of the admixture of light carburetted hydrogen gas. This opinion he dissented from, as it was well known that, in coal-mines, the fire-damp, as this gas was called, was inhaled with perfect impunity. To ascertain the modus agendi of the gas when inhaled, he made numerous experiments, by immersing animals in different mixtures of it and atmospheric air, as well as in the pure

ga

In the latter case, the animals died asphyxiated, as when immersed in water or mercury, the spasm of the glottis preventing any portion of it from being inhaled. If not more than 25 per cent. be present, then respiration will go on, and its true poisonous effects take place. As to the amount of this gas necessary to produce fatal effects, Dr. Bird found that, as a general rule, any quantity above 3 per cent. was capable of producing death. Two opinions prevailed on the nature of these properties: the first was, that the gas acted negatively, as pure nitrogen or hydrogen is known to do, by preventing the due supply of oxygen. To test this opinion, was formed a mixture containing twenty-one parts of oxygen, and seventy-nine of carbonic acid, and death followed instantly from immersion in it; whilst the same result followed when the proportions were reversed, although a taper burned brilliantly in the latter combination; showing, that the burning of a light in any suspected situation is not always a safe test of the absence of danger. The second opinion is, that this gas, when respired, exerts a specific poisonous action on the nervous system. This latter Dr. Bird adopts, from various considerations drawn from his direct experiments, and from the symptoms observed in numerous cases. Athenæum.

GAS FROM GRAPES.

An interesting experiment has been made at Bourdeaux, on the husks of grapes, when pressed, and the lees of the wine, in order to show their use for the purposes of lighting. A pound of the dried husks put into a red-hot retort, gave, in seven minutes, 200 litres of gas, which burnt with an intense light, and free from smoke or smell. A second experiment with the dried lees was equally satisfactory.

NEW MODE OF PREPARING CARBURETTED HYDROGEN GAS.

THIS invention has gained for M. Selligue the premium of 2000 francs proposed by the Société d'Encouragement of Paris. It consists in obtaining pure hydrogen by decomposing water by means of incandescent charcoal, and then carburizing it by mixture during the simultaneous decomposition of another liquid substance, rich in carbon and hydrogen. Among all known substances, that which appears to answer best is the oil of schist (l'huile de schiste).

The furnace is composed, 1st, of three vertical retorts, communicating, so as to form only one. In a double furnace, there will be six retorts. These are all open at both ends, but closed below by sliding stoppers, (couvercles rodès), so that simple contact and the least pres

sure are sufficient to shut them firmly. The top of each retort is closed by a head fixed by keyed gudgeons and iron cement. Each head bears itself a stopper, or cover, like those below.

The first retort into which steam is introduced through a tube communicates below, by a tube twice bent, with the second, which connects at top with the third by a similar tube; and this third retort has, below, a vertical tube with branches, by which the gas is conducted to a refrigerator, and thence to the gasometer. This tube dips into a trough of water, to serve as a hydraulic closure. The third retort bears at top a funnel syphon, through which the carburizing substances are introduced. 2nd, Two horizontal tubes, placed in the sides of the vault, serve as boilers to vapourize the water; each communicates at one end with the first retort by an arched tube, and to the other end is attached a funnel syphon, by which the boiler is supplied with water. 3rd, Two furnaces. 4th, A chimney in four parts, uniting at first into two, and then into one, in order to regulate the fire with greater ease.

Operation.-Having filled with charcoal the first two retorts in each of the (double) furnaces, and suspended chains in the two last, in order to increase the surface, the fire is lighted; and when the retorts have attained a cherry red heat, a gentle flow of water and oil is made through the syphons. The water falling into the boilers is instantly evaporated, passes into the first retort, then into the second, where it is deprived of its oxygen; and, reaching the third, the hydrogen alone mingles with and carries along the carbonated hydrogen simultaneously formed from the oil in the last retorts.

The united gases then issue from the lower end of the third retort, and press off through the branches, while the more volatile matters are deposited in the reservoir of water. -Annales des Mines; Mechanics' Magazine.

GAS PRODUCED BY A NEW PROCESS.

An experiment in Gas-lighting by the Comte de Val Marino has been made in the presence of several scientific gentlemen. A small gasometer was erected for the purpose, which was connected by tubes with a furnace built of brick, and containing three retorts, one of which was supplied with water from a syphon; another was filled with tar; and both, being decomposed in the third retort, formed the sole materials by which the gas was produced. The principal agent employed to produce the gas was common water combined with tar; but, according to the theory of the inventor of this new species of gas, any sort of bituminous or fatty matter would answer the purpose equally as well as pitch or tar. After the lapse of about half an hour employed in the experiment, the gas was turned into the burners, and a pure and powerful light was produced, perfectly free from smoke or any unpleasant smell. The purity and intenseness of the flame were tested in a very satisfactory manner. The great advantage of this sort of gas over that produced from coal consists, it was said, in the cheapness of the materials employed in its production, the facility with which it is manufactured, and the perfection to which it is at once brought, without the necessity of its undergoing the tedious and expensive process of ⚫ condensation and purification; for, in this instance, as soon as the preliminaries were completed, the light was produced in a perfect state within a few feet of the gasometer; which, although of inferior size, was said to be capable of affording light for 10 hours to at least 500 lamps or burners. It was also stated, that 1,000 cubic feet of gas manufactured by this process could be supplied to the public for about onethird the price now charged by the coal-gas companies: and it was said to be equally available for domestic use, and more safe than the common gas, inasmuch as small gasometers might at a trifling expense be fixed at the back of grates in private dwellings, from which the gas could be conveyed in India-rubber bags to any part of the house, thereby preventing the many accidents which occur by the use of tubes and pipes. The Comte de Val Marino has taken out a patent for his discovery, and he has improved upon the burners now in use, so as to render the light produced more pure and intense. For this improvement he is also secured by a patent.-Times; abridged.

MINERAL SPRING IN NEW SOUTH WALES.

DR. F. LHOTSKY has described in the Philosophical Magazine a Spring situated on the Menero Downs, 300 miles from Sydney, and skirting the Australian Alps on their eastern side. The formation about the spring is calcareous, and the immediate neighbourhood of it is formed by an extensive level of travertine, just like that with which the plains of Romagna are covered. The spring formed (after having been enlarged by Dr. Lhotsky), an aperture of 3 feet in diameter, and the water of a nearly constant temperature of 50° Fahr., with the air at a temperature of 98°. The water is perfectly clear, and only disturbed by the continued evolution of carbonic acid gas, with a large quantity of which the water is saturated. This having been subjected to evaporation, yields a salt, which Prof. Daubeny describes as containing muriates, calcareous earth in combination with carbonic acid, a trace of magnesia, and iron. The salt which effloresces upon the travertine level near the spring, contains carbonate of lime, common salt, a little sulphate of soda, and some peroxide of iron. The water has the taste of Seltzer water.

BRINE SPRING IN BAVARIA.

PROF. FORBES, in a paper read to the Royal Society of Edinburgh, on January 7th, gives the following details of the produce of an Intermitting Brine Spring discharging Carbonic Acid Gas, near Kissengen, in Bavaria.

The mineral discharge of the spring consists of from 35 to 40 Bavarian cubic feet per minute. The gas consists, according to Kastner, of almost pure carbonic acid, with a trace of azote. A pound of water is combined with 30+ French cubic inches of gas: but this gives no idea of the quantity which is evolved wholly uncombined. The specific gravity of the water varies from 1.064 to 1.030; and the solid matter in 1000 grains of water compared with that of sea-water by Dr. Murray, (sp. gr. about 1,028, are, Kissengen, 22-37230 gr.; seawater, 30-309 gr.; carbonic acid in the Kissengen water, 2-06380