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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 experiments. is as follows: Dis solve 100 grains of mercury in an 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, and crystals appear, which augment on cooling. They are of a greyish white, hard to the touch, and heavy. They are to be separated from the liquid by filtering; to be washed in pure water, and dried in a heat not exceeding 212o. b. By being dissolved and crystallized two or three times, they beb come brilliant, white, and silky, and have a faint metallic lustre. We must caution our readers how they meddle with this substance, as it detonates if heated to upwards of 3000, by the blow of a hammer, by friction, and by electricity. Indeed, as the French chemist, from whom we took the former article, observed, it detonates if struck or agitated with glass rods; and there, fore the greatest precaution is necessary, both in preparing and using it. When it detonates, its effects are very violent, but they to do not extend far,

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 brimstone match. Thus, hold a 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.

and, towards the close, a great quantity of gaseous oxide of carbon are disengaged. All the car1309 bon not carried off in these va- 10 rious forms remains in the still, and generally preserves the form of the vegetable substance em-1 ployed. Since we have learned nature of all these products, the Log process has been much improved, of and particularly by charring the w wood, and by turning the otherto products to advantage." In the forests the wood is first charred, so as to dissipate all the water of getation. It is then introduced Marie into a large circular or square potza00 A, made of iron plates rivetted of together, and having at its uppered part a small lateral iron cylindero an iron cover, B, is closely fitted w to this pot, and then it is lifted by means of a crane, or other mecha- T nical power, and placed in the furtaib to booniq bas 20161899itaib

nace, D, of the same sho same shape as the pot, and the furnace is then covered with a lid. E, constructed in masonry. moderate heat is then applied to the furnace; at first the vapour of the wood is dissipated, but this vapour soon ceases to be transparent and becomes sooty. At this a tube or cylinder, enclosed in another of brick-work or tiles, is affixed to the lateral cylinder, and forms the condensing apparatus. This is different in different places; in some the condensation is effected by the air, the vapour being made to pass through a long extent of cylinders, and sometimes of adapted to each other, but most generally the condensation or cooling is effected by water, when it can be procured in sufficient quantities. The most simple apparatus for this purpose consists of two cylinders, F E, enclosed one within the other, and having between them a space sufficient to allow a large quantity of water to flow backwards and forwards and thus cool the vapour, These cylinders are adapted to the distilling apparatus, and placed

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inclined to the horizon. To this first apparatus a second, and sometimes a third is adapted, and placed in a zig-zag form, in order to occupy as little space as possible. The water is made to circulate in the following manner:-At the lower extremity, G, of the condensing apparatus, there is a tube which ought to be somewhat higher than the upper part of the whole of this apparatus, where, at H, there is another short tube curved towards the ground. Water from a reservoir is made to run through the perpendicular tube t to the lower part of the condensing apparatus, and fills all the space between the cylinders. When the operation is going on, as the vapours are condensed they raise the temperature of the water, which becoming more rarefied and lighter, flows out of the a curved tube,

The condensing apparatus terminates in a brick canal, I, covered and buried in the earth. At the end of this canal is a bent tube, K, which carries the liquid products into the first cistern; when it is full it discharges itself by means of a syphon into a large reservoir; the tube which terminates the canal plunges into the liquid, and thus cuts off the communication with the interior of the apparatus. The gas which is disengaged is conveyed by means of the tube, IL, from one of the sides of the canal, I, above the ash-hole of the surface. This tube has a stop-cock, M, before reaching the furnace, in order to regulate the quantity of gas and cut off the communication at pleasure. That part of the tube which ends at the furnace rises perpendicularly some inches, and terminates, as seen, at N; by this means thes gas may be distributed, equally ty under the vase without any risk of the tube being obstructed by either the combustible or the cinders.he

Towards the end of the operation the heat is increased so as to make the iron pot red hot; and the ch time when the operation is com-d pleted is ascertained by the colour 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 combustion 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 ascribed 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 eto a dry and sound state. If fish be simply dipped in re-distilled pyrolignous acid, and afterwards dried 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, ail

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.

(By M. Berzelius.)

M. BERZELIUS, the Swedish chemist, and one of the most scientific and celebrated men of the day, has oldescribed, in a letter to M. Dulong, 2 an extract of which has been published in the Annales de Chimie et de Physique for May, a mode of preparing silicon, with its qualities. Of this extract the following is an abridgment: "Fluoric acid is one of the most convenient agents for the analysis of organic products; and it dissolves things which the other acids will not touch. It has supplied me with the means of determining with more

sertion in The Chemist, you will much oblige, Sir,

Your obedient humble servant,
JAMES MARSH..

accuracy the weight of the atoms of several substances, concerning which I entertained some doubts. To extract the alkali of minerals, it was sufficient to expose them to the action of fluoric acid, or to the action of a mixture of the fluate of lime and of sulphuric acid. In attempting to reduce fluoric acid by potassium, I succeeded in reducing silica, zirconia, and some other earths, but I was able to obtain only silicon and zirconium in a separate state; the others decompose water with great energy. Pure silicon is incombustible even in oxygen gas. Neither water, nitric acid, caustic potash, nor » aquaregia have the least effect upon it;