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ON MAKING EXPERIMENTS.

When the study of Chemistry is pursued with zeal, numerous experiments will be made, and they can never be conducted with success, unless great order and regularity are preserved. Every vessel and utensil ought to be well clcanedas often as they are used, and put again into their place. Every one which contains any substance whatever, or which is habitually employed to contain any substance, even water, should have a label pasted on it, with the name of the substance legibly written. This may appear troublesom e, but it is

essentially necessary. Several substances, perfectly different in many of their properties, have precisely the same appearance, and are liable to be mistaken for one another, causing the chemist to lose all his labour. When a person is keenly engaged, experiments succeed each other quickly; some seem nearly to decide the matter, and others suggest new ideas, which he cannot but proceed to immediately; thus he is led from one to another: he thinks he shall easily know again the products of the first experiments, and therefore he does not take time to pat them in order; he prosecute! with eagerness the experiments which he has last thought of, and, in the mean time, the vessels employed, the glasses and bottles filled, so accumulate, that he cannot any longer distinguish them, or at least he is uncertain concerning many of his former products. The evil is increased if a new series of operations succeed, and occupy all the laboratory; or if he be obliged to quit it for some time, every thing then goes into confusion. Of the results of this carelessness, and multiplying vessels' and utensils, we have a remarkable instance in the few anecdotes which are preserved of Peter Woolfe, an eminent alchymist of the last century, and one of the latest persons who believed in the possibility of finding the philosopher's stone, and the universal medicine, which was to give health and preserve life for ever. While in London, he lived in Barnard's-inn, and his rooms, which were extensive, were so filled with apparatus, that it was difficult to get to bis fire-side. A friend of his calling on him one day, laid down his hat among the numerous packages, and such was the confusion that he could never find it again.

"When new researches and inquiries are made, the mixtures, results, and products of all the operations ought to be kept a long time, distinctly labelled and registered ; for these things, when kept some time, frequently present phenomena that were not at all suspected. Many fine discoveries in chemistry have been made in this manner, and many have certainly been lost by throwing away too hastily, or neglecting the products.

Since Chemistry offers many views for the improvement of many important arts; as it presents prospects of many useful and profitable discoveries, those who apply their labours in this way ought to be exceedingly circumspect not to be led into a useless expense of time and money. In a certain set of experiments, some one is generally of an imposing appearance, although, in reality, it is no

thing more. Chemistry is full of these half successes, which serve only to deceive the unwary, to multiply the number of trials, and to lead to great expense before the fruitlessness of the search is discovered.

IMPORTANT DISCOVERY,

With its Applications,

BY SIR HUMPHREY DAVY.

In the Philosophical Transactions for 1823, there is a valuable paper by Sir H. Davy, under the title, " On the Application of Liquids formed by the Condensation of Gases as Mechanical Agents:" which introduces to the notice of the world A New Mechanic Power, superior, apparently, to steam, and which may one day entirely supersede it. A few years ago, writers on the theory of mechanics laid it down as an axiom, that there were a certain number of mechanic powers, such as the lever, the wedge, the screw, &c, which it was impossible the wit of man should ever increase. Nature, however, does not work by means of levers, wedges, or screws, and it was reserved for the Chemist to find out the mechanic powers she really does employ. He detected them in his retorts, and applied them in cauldrons and pistons, till he needs nothing but whereon to place his apparatus to move the world. The Chemist,according to Lord Bacon's theory, is the true philosopher; and after finding out the processes which nature employs, he overcomes her by combining her art with his own. One of her most favourite instruments is repulsion, with which every part of matter is endowed. We do not claim the discovery of this fact for the Chemists, (for it has long been known) but they have great merit in extending its application to the improvement of the arts. The changes which substances undergo, are effected by properties which belong to them or to the substances acting on them; and few or no such changes take place, of which repulsion is not the effective cause. This natural mechanical power, if we may so term it, is great in proportion as it is opposed. If permitted to pursue its own course, it is unseen and unfelt; and we must observe closely, remember attentively, and reason correctly, before we can discover its existence. Though the Chemist cannot be said to have found out this power, he has taught us, in a great measure, to augment it at our will, and partly to regulate its action. Of all the bodies in which it is found, those which usually assume the gaseous form seem to possess it in the greatest degree; and many of these it has lately been the great merit of Sir H. Davy to reduce to a liquid state. When in this form, and under a pressure equal to that of 20, 30, or 40 atmospheres, they have a continual tendency to resume the aeriform state, and a small increase of temperature developes a prodigious power. Thus he has caught and fixed that mighty agent which wafts and spreads them far and wide through the atmosphere, so that he can direct its action; and he is now teaching us how to apply it. If we do not mistake, the power of man over the elements seems now likely to obtain—if it may not be said to be now only begun,—a great extension; and the struggle which has been carried on since the history of our race commenced, between mind and matter, seems at length about to terminate, by the former achieving a glorious victory. But we shall not detain our readers with our remarks, but proceed to lay before them an abridgment of the Papers of Sir H. Davy and Mr. Faraday.

Mr. Faraday, in the beginning of 1823, took advantage of the cold weather to procure crystals of hydrate of chlorine, and, at the request of Sir H. Davy, subjected them to the following experiment: After being dried as well as they could be by bibulous paper, they were introduced into a sealed glass tube.the upper end of which was hermetically closed. On the tube being placedin wateroflOO°,thesubstance fused, and was filled with a bright

yellow atmosphere. On examination, the tube was found to contain two fluids; one, about three-fourths of the whole, was of a pale yellow colour, having somewhat the appearance of water; the other was a heavy, bright yellow fluid, lying at the bottom of the tube, with no apparent tendency to mix with the former. As the tube cooled, the yellow atmosphere condensed with more of the yellow fluid, looking like cloride of nitrogene, and at 70' the pale portion congealed, though even at 30' the yellowportion did not become solid. From this experiment Mr. Faraday was led to suppose that the chlorine had been entirely separated from the water by heat, and condensed into a dry fluid by the mere pressure of its own abundant vapour. If this supposition were correct, chlorine gas, when condensed, should be compressed into the same fluid; and Mr. Faraday, subjecting this gas, after being completely dried, to a considerable degree of pressure in a tube connected with a condensing syringe, succeeded in forming the yellow fluid. This fluid is therefore considered, both by this gentleman and Sir H. Davy, as pure chlorine in a liquid state. By similar experiments, the illustrious President and his assistant succeeded in procuring liquid muriatic acid, liquid sulphurous acid, liquid sulphuretted hydrogen, liquid carbonic acid, fluid euchlorine, liquid nitrous oxide, and liquid ammonia. A number of experiments were also made on other gases, some of which, as hydrogen, oxygen, phosphuretted hydrogen, resisted condensation, though subjected to great pressure. Mr. Faraday describes, at considerable length, the properties of these various substances, in which we must for the present postpone following him, to come more immediately to the Paper of Sir H. Davy, and the application of this discovery to the arts. Sir H. Davy, after stating that, owing to the laws according to which the elasticity of vapour increases under high pressure, some

doubts most be entertained as to the economy of employing steam, under great pressures at high temperatures, says, " that no such doubts can be entertained with respect to the use of such liquids as require even for their existence a compression equal to that of the weight of 30 or 40 atmospheres; and where common temperatures, or a slight elevation of them are sufficient to produce an immense elastic force; and when the principal question to be discussed is, whether the effect of mechanical motion is to be most easily produced by an increase or diminution of heat by artificial means?" Sir H. Davy then goes on to say, " that he has made experiments on this subject, with the assistance of Mr. Faraday, and found that sulphuretted hydrogen, which condenses readily into a fluid at 38 Falir., under a pressure which balances the elastic force of an atmosphere compressed to l-14th, has its elastic force increased so as to equal that of an atmosphere compressed to l-17th, by an increase of 47° of temperature. Liquid muriatic acid at 3 exerted an elastic force equivalent to that of an atmosphere compressed to l-20th; by an increase of 22° it gained an elastic force equivalent to that of an atmosphere compressed to l-25th; and by a further addition of 26°, an plastic force equivalent to that of an air condensed to l-40th of its primitive volume." "Here, then," says an able commentator on this statement, " by alternately heating sulphuretted hydrogen gas up to 50, and cooling it down to 3 degrees,we generate a force equal to the pressure of three atmospheres. Itis found," he adds, "that the elasticity thus developed varies in different gases, and that it is greatest in those which are most dense. Carbonic acid, one of the heaviest gases, has in its liquid state an elastic force equal to 20 atmospheres at 12 Fahr., but at 32 it has a force equal to 36 atmospheres; so that by the addition of 20° of heat, we generate a force equal to 16 atmospheres, or 16 times as great .as that of steam

in low-pressure engines." "In applying the condensed gases as mechanical agents," says Sir H. Davy, " the apparatus must be at least as strong, and as perfectly joined, as that used by Mr. Perkins in his high-pressure engine; but the small difference of temperature required to produce an elastic force equal to the pressure of many atmospheres, will render the risk of explosion extremely small. And if future experiments should realize the views here developed, the mere difference of temperature between sunshine and shade, or air and water, or the effects of evaporation from a moist surface, will be sufficient to produce results which have hitherto been obtained only by a great expenditure of fuel." After stating this application of his discoveries, Sir H. Davy adds, "There can be little doubt that these general facts of the condensation of the gases will have many practical applications. They offer easy methods of impregnating liquids with carbonic acid and other gases, without the necessity of common mechanical pressure; they afford means of producing great diminutions of temperature, by the rapidity with which large quantities of liquids may be rendered aeriform; and as compression, like cold, prevents the formation of elastic fluids, there is great reason to believe that it may be successfully employed for the preservation of animal substances which serve for food."

We observe by the Annalen der Phi/sik, Sfc. for November 1823, in which there is an account of these experiments, that the celebrated German Professor, Mr. Dobereiner, endeavoured, two years ago, to accomplish what lias now been successfully performed by the English Chemist. He then remarks, It is probable, since oxygen, hydrogen, and azote, which are considered as simple substances, resist condensation, and since most of the gases condensed by Mr. Faraday are compound substances, that the chlorine operated on by him is also a compound substance, and probably contained water. The Professor considers chlorine as a compound of muriatic acid and euchlorine, or what the Chemists of our country also call protoxide of chlorine.

HOW TO MAKE ISINGLASS.

There seems little doubt that this substance, which is so extensively employed in the arts, and which consists nearly altogether of gelatine, may be made from almost any species of fish, but certainly as well from several of those species which frequent our own shores and rivers, as from those which are found in the rivers of Russia, whence we import vast quantities of Isinglass into Great Britain. The French, we observe, arc making efforts to naturalize a manufactory of Isinglass in their own country; and large premiums have been offered to those persons who shall manufacture it equal to the Isinglass imported from Russia. The following is the method said to be followed in the latter country to prepare this substance, and recommended for adoption in France: The Russians divide the large air bladders of the sturgeon lengthwise, and wash them in very weak: lime-water. They strip off the fine membrane or skin which covers these bladders, and wrap them up in wet linen, and bruise them and wet them till -they become soft as paste. They then spread them out, afterwards roll them together, and bend the roll into the form of a heart, the two ends being fastened together by means of a Wooden peg. These rolls are then suspended in the air to dry, and when dry are fit for use. The Russians, however, do not limit themselves to the swimming bladders of the sturgeon, but employ almost all the membranes and cartilaginous parts of several other fish; and it seems certain that Isinglass may be procured from almost all kinds of fish, whether they live in salt water of fresh.

AN ALCHYMIST.

THE HISTORY OF ELIA8 THE ARTIST AND DR. HELVET1US.

On the 27th of December 1666, says Dr. Helvetius, in the afternoon, a stranger came to my house at the Hague, in a plebeian habit

of honest gravity and serious authority, of a mean stature and a little long face, black hair not at all curled, a beardless chin, and about forty-four years of age, ahd born in North Holland. After sa^ lutation, he beseeched me with great reverence to pardon his rudfc accesses, for he was a lover of the pyrotechnical art, and having read my treatise against Sir Kenelm Digby, and observed my doubt about the philosophic mystery, induced him to ask rnc if I was a disbeliever as to the existence of a universal medicine which would cure all diseases, unless the principal parts were- perished, or the predestined time of death come. I replied, " I have never met with an adept, or saw such a medicine, though I had fervently prayed for it." Then I said, "you are surely a learned physician." "No,'' said he, " I am a brass-founder, and a lover of Chemistry." He then took from his bosom-pouch a neat ivory box, and out of it three ponderous lumps of stone, each about the bigness of a walnut. I greedily saw and handled, for a quarter of an hour, this most noble substance, the value of which might be some*Where above twenty tons of gold, and having drawn from the owner many rare secrets of its valuable effects, I returned him this treasure of treasures with a most sorrowful mind, humbly beseeching him to bestow a fragment of it on me, in perpetual remembrance of him, though but the size of a coriander seed. "No, no," said he, "that is not lawful, though thou wouldst give me as many golden ducats as would fill this room, fof it would have particular consequences; and if fire could be burned of fire, I would, at this instant, rather cast it all into the fiercest flames." He then asked me if I had a private chamber, whose prospect was from the public street: so I conducted him into my best furnished room back, which he entered without wiping his shoes, though they were full of snow and dirt. I now expected th,at h,e wQvUd bestow some great

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