rass, surrounded by a mixture of two parts of ice and one part seasalt. Sulphurous acid is thus liquefied completely under the pressure of the atmosphere, and at a temperature not lower than 180 to 200 of the centigrade thermometer, or from 00 to 40 of Fahr. It is then transparent, inodorous, and heavier than water. At 14° Fahr. it boils, but may be preserved liquid for a long time, without having recourse to pressure, because the part which is converted into vapour absorbs so much caloric as to preserve the remainder below its boiling temperature. Poured into the hand, it produces the most intense cold, and is completely evaporated. TO CONVERT WATER INTO ICE. Pour some of this sulphurous acid into water; one part is converted into vapour, another dissolved by the water, but as the water begins to be saturated, the acid collects in drops at the bottom of the vessel, like an oil heavier than water. If it' be touched with a tube, or rod, it is converted into a vapour, and occasions a species of ebullition; temperature of the water sinks, and its surface is covered with a coat of ice; and the whole of the water may be frozen by adding the acid in proper quantity. the TO PRODUCE AN EXCESSIVE DEGREE SIMPLE MEANS OF LIQUEFYING ›› It seems to us that the above ex- Surround the bulb of an air thermometer with cotton; dip it into sulphurous acid, and then allow the acid to evaporate spontaneously in the air. By making the experiment at the temperature of 100 centigrade (45o of Fahr.), a diminution corresponding to -570 of centigrade (or-720 of Fahr.,) takes place; and if the thermome ter is placed in the vacuum of an air-pump, the temperature is reduced to 68° of centigrade, (or -91 Fahr.) It must be observed, TO PREPARE FULMINATING however, that only an air thermoMERCURY! ~ (Toado meter can be employed to indicate this low temperature with accu(In answer to a Correspondent) A CORRESPONDENT has particularly requested us to inform him how this substance is prepared and as he states this knowledge will be of considerable importance to him, racy. TO FREEZE MERCURY. Cover the bulb of a thermometer with cotton, pour over it sulphurous acid, and swing it in the air; V bs we shall not delay answering him. At the same time, we must confess that other Correspondents have a prior claim on us; but having published their queries, we still are in hopes some of our readers will answer them. Ifwe do not soon receive some satisfactory answers, we shall answer the queries ourselves. The discovery of fulminating mercury was made by Mr. Howard, and his process is still recommended by the most celebrated chemists, and was followed by Messrs. Gay Lussac and Leibig, in their late experime It is as follows:-DisSolve of mercury in an 0 grains s ounce and a half by measure of nitric acid, of the specific gravity of 1.3; add to the mixture two ounces by measure of alcohol, or pure spirit, and apply heat to the flask containing the mixture till it begins to boil; then remove the flask from the lamp. The action becomes violent, and continues for some time; a dense white smoke issues from the vessel, which is heavier than air. At first a little nitrate of mercury is deposited, but this is soon redissolved, the liquid becomes grey, from the reduction of a part of the oxide of mercury; after some time it becomes yellow, 2 and crystals appear, which augsment on cooling. They are of a 25 greyish white, hard to the touch, Is and heavy. They are to be separated from the liquid by filtering; a to be washed in pure water, and aidd dried in a heat not exceeding 2120. be By being dissolved and crystallized two or three times, they beba come brilliant, white, and silky, and have a faint metallic lustre. We must caution our readers how 32 they meddle" with this substance, be as it detonates if heated to upwards of 3000, by the blow of a hammer, by friction, 1, and by electricity. In deed, as the French chemist, from Dwhom we took the former article, observed, it detonates if struck or agitated with glass rods; and there fore the greatest precaution is nehdessary, both in preparing and Wousing it. When it detonates, its as effects are very violent, but they to do hot extend far, f 11 AN INFALLIBLE BAROMETER. PUT two drachms of pure nitre and half a drachm of chloride of ammonia, reduced to powder, into two ounces of spirit of wine, or pure alcohol, and place this mixture in a glass tube, ten inches long and eight lines in diameter, the upper extremity of which must be covered with a piece of skin or bladder, pierced with small holes. If the weather is to be fine, the solid matters remain at the bottom of the tube, and the alcohol is as transparent as usual. If rain is to fall in a short time, some of the solid particles rise and fall in the alcohol, which becomes somewhat thick and troubled.When a storm, a tempest, or even a squall is about to come on, all the solid matters rise from the bottom of the tube, and form a crust on the surface of the alcohol, which appears in a state of fermentation. These appearances take place 24 hours before the tempest ensues; and the point of the horizon from which it is to blow is indicated by the particles gathering most on the side of the tubes opposite to that part whence the wind is to come. TO BLEACH ROSES AND OTHER FLOWERS. As this is the season when flowers are plentiful, our readers may easily put the following to the test of experiment. Sulphurous acid destroys most vegetable colours, but the blues are reddened by it previously to being discharged. Flowers of a blue colour may, therefore, by the action of this acid be converted to red, and all the reds may be made white. The action of sulphurous acid may be obtained by burning a common Thus, hold a brimstone match. rose over its blue flame, and the colour will be discharged wherever the flower comes into contact with the acid, so as to render it beautifully variegated, or altogether white. If it be dipped into water, after a season the redness will be restored. grows thicker and darker, augment w but this vapour soon ceases to be transparent and becomes sooty. munication with the interior of which is At this time a tube or cylinder, the apparatus. The gas enclosed in another of brick-work disengaged is conveyed by means els or tiles, is affixed to the lateral of the tube, I L, from one of the cylinder, and forms the condensing sides of the canal, I, above the apparatus. This is different in dif- ash-hole of the surface. This tuber ferent places; in some the condens- - has a stop-cock, M, before reach-os ation is effected by the air, the va- ing the furnace, in order to regu-s pour being made to pass through a late the quantity of gas and cut offedt long extent of cylinders, and some- the communication at pleasure.ge some-t times of casks adapted to each That part of the tube which ends as other; but most generally the con- at the furnace rises perpendicu-qo densation or cooling is effected by larly some inches, and terminates, W water, when it can be procured in as seen, at N; by this means thei sufficient quantities. The most st gas may be distributed equally d simple apparatus for this purpose under the vase without any risk of be consists of two cylinders, F E, en- the tube being obstructed by either ol closed one within the other, and the combustible or the cinders.d bas having between them a space suf- Towards the end of the operaficient to allow a large quantity of tion the heat is increased so as to sa water to flow backwards and for- make the iron pot red hot; and the qe wards and thus cool the vapour, time when the operation is com- odr These cylinders are adapted to the pleted is ascertained by the colour distilling apparatus, and placed of the gas flame. At first it is of a reddish yellow, then it becomes blue, and finally it is quite white, which is a mark that the combus tion is carried far enough; or a few drops of water are let fall on that part of the tube close to the furnace which is not surrounded by water, and when it evaporates without noise the calcination is thought to be sufficient. The adapting tube is then separated, and the end of the condensing cylinder is closely stopped by iron plates and brick earth. The lid of the furnace is then lifted off, and afterwards the pot is taken out and immediately replaced by another which has in the meantime been prepared. When the pot which has been taken out is cold, the wood is removed. The acid is then purified; but we shall not at present describe this part of the process, preferring to take from an English work a short account of the various uses of pyrolignous acid. It is sufficient to plunge meat for a few moments into this acid, slightly empyreumatic, to preserve it as long as you please. It not only stops putrefaction, but restores the substance in which this decomposition has begun to a sound state. This effect has in part been as cribed to the empyreumatic oil, and hence the beneficial effects of smoke in preserving meats and fish. By pouring this acid over anatomical preparations, Dr. Jorge, of Leipsic, lately restored some of them from a state of beginning putrefaction. Pieces of meat smeared with empyreumatic oil or tar, although far advanced in a state oof putrefaction, and although the weather was warm, were restored icto a dry and sound state. If fish be simply dipped in re-distilled pyrolignous acid, and afterwards adried in the shade, they preserve perfectly well, and on boiling them they have not such a taste of empyreumatic oil as to be disagreeable. Haddocks have been salted for six hours, then dipped in pyrolignous acid, and hung up in the shade for six days, and on being dressed were found of a very fine flavour. Beef treated in the same way had the taste of Hamburgh beef and kept as well. Meat to which this acid was applied, with a sponge or wet cloth, kept several days longer in summer than it otherwise would. When the acid has become impure by frequent use, it may be clarified by beating up a dozen eggs with 20 gallons, and heating the mixture in an iron boiler. Before boiling, the eggs coagulate and bring the impurities to the surface, when they are carefully skimmed off. The acid acts on iron, and must therefore be immediately removed from the boiler. Besides these antiseptic qualities of the pyrolignous acid, it has long been used by the calico-printers, though under its more correct name of vinegar. GAIN OF POWER BY MA CHINERY. It was estimated about six years ago, by three of the most eminent cotton-spinners in Great Britain, that the quantity of cotton thread produced on an average by each spinner, compared with that which one person could have spun on a single wheel, as was the practice before the inventions of Arkwright and others, was as 120 to 1. By improvements since made, this has probably increased to 150 to 1; but taking only the smaller estimate, one person can now produce as much as 120 could have produced prior to these inventions. At present, 280,000 persons are engaged in this country spinning cotton thread, and multiplied by 120, this gives 33,600,000 as the number of spinners who would have been required under the old system to produce as much cotton thread as is now spun in Great Britain, it There is one steam engine at present in Cornwall of 260 horse power, which works day and night; each horse power is estimated as equal to the unassisted labour of six men; and as it would require three sets of men, each set working eight hours, to labour as constantly as this engine, it follows that it does as much work as 4690 persons, |