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a time of greater or less duration, the sensibility of ani mal bodies.

Of the numerous ills that flesh is heir to, one, by no means the least grievous, is the contingency of having to part with an unsound limb, or otherwise to undergo the process of being dissected alive, commonly called a surgical operation. It has long been an axiom in chirurgical science, that the operator should endeavor, to the extent of his ability, to perform his vivisection “tuto, cito, et jucunde” -safely, speedily and pleasantly. Modern advancement in anatomy and physiology, and refinement in dexterity, had enabled surgeons to comply, in a great measure, with the two former requisitions; the latter still remained certainly unfulfilled. The horrors of ancient surgery had been mitigated; but all that skill and knowledge could do or suggest failed, signally, to make things pleasant, in any considerable degree, to the individual under the scalpel. So far agreeable, however, as the prospect of a comfortable doze, with the expectation of awakening relieved of a torment or a burden, can make a surgical operation, it has, at last, been rendered. Everybody is aware that, during the extraordinary slumber induced by the inhalation of chloroform, operations of the first magnitude and the greatest difficulty may be painlessly undergone. Consciousness is suspended, sensation placed in abeyance. Muscles, tendons, bones, even nerves, are cut and sawn through with little or no inconvenience to their proprietor. A man is lopped and pruned like a tree; he is carved and hewn, and squared, as if he were a log; and is, indeed, the mere apathetic subject of medical carpentry.

Whilst the bodily edifice is under surgical repair, for the advantage of being enabled to avoid the annoyance attending the cognizances of that process, by taking, with

ease and convenience, an excursion into the land of sleep, every lifeholder of the tenement in question is indebted to Dr. Simpson of Edinburgh. The peculiar power of chloroform to produce insensibility, was determined by his researches. For some time previously, sulphuric ether, the discovery of Dr. Jackson and Mr. Morton of Boston, in America, had been in use for the same purpose. There were, however, objections to its employment. A larger quantity of it than was consistent with safety, required occasionally to be administered to produce the desired effect. Its odor was disagreeably strong and permanent; and what was worse, it not unfrequently excited irritation in the chest. In search, therefore, of a more safe and commodious anæsthetic agent, Dr. Simpson tried a series of experiments, principally on his own person, with a variety of volatile substances; and the result was, his announcement, in 1847, of the desideratum as being supplied by chloroform.

The existence of this substance, chloroform, had been known to chemists since 1831, in which year it was discovered by Soubeiran. Very little later, in 1832, an independent discovery of it was made by Liebig. Dumas, in 1835, was the first to ascertain its exact chemical composition.

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When, in our nursery days, we used to read of some wonderful balsam, by means whereof well-disposed magicians and benevolent fairies were wont to charm away the pain of injuries inflicted by dragons and ogres on the persons of good knights and serviceable giant-killers, a very natural desire arose in our minds for information concern ing the nature and composition of the marvellous remedy. Those who are not conversant with chemical details, and who may, in spite of hope to the contrary, one day have a tooth to be extracted, or a nail to be plucked out-not to

suggest more formidable interference of a manual or anatomical description with the living mechanism-will probably feel a similar, and at least an equal curiosity, with regard to the rather more practically interesting subject of chloroform.

Chloroform is a bright colorless liquid in appearance resembling spirit of wine, which it further resembles in being extremely volatile, but differs from it remarkably in being much more dense; for it is considerably heavier than water, in which it sinks. Unlike spirit of wine, too, it is not inflammable. It has an agreeable, fragrant, ethereal, fruit-like smell, very similar to that of a ripe apple; and a sweet taste. Chloroform boils at one hundred and fortyone degrees, and its vapor exceeds in density that of the atmosphere in somewhat above the proportion of four to The ready volatility of a fluid comparatively so ponderous as chloroform may appear singular.

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Chloroform, considered as a noun substantive, may said to be an abbreviation-not to employ the more equivocal expression, alias. In legal phraseology-according to the statutes of chemistry-it is called per-chloride of formyle, signifying formyle united with its maximum of chlorine. More strictly still, it is denominated ter-chloride instead of per-chloride, to denote that the proportions in which the chlorine is combined with the formyle are three of the former to one of the latter. Now, formyle is a substance supposed to be the base, or fundamental, or essential constituent part of an acid called formic acid. Formic acid is so termed from having been first discovered in red ants, the Latin for ant being formica; it consists of three proportions of oxygen, in combination with one of hydrogen and two of carbon. But if such is the composition of formic acid, what, it will be asked, was meant by the

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statement that its base is formyle? This seeming puzzle is solved by the explanation, that formyle is not conceived to be a simple element, but a substance analogous to one, constituted by the two proportionals of carbon and one of hydrogen in the formic acid. Here it must be remembered that a chemical compound differs essentially from a mechanical mixture. Things mixed mechanically are separable particle from particle; sulphur from charcoal; chalk from cheese. In a chemical compound, the least particle that can be got by mechanical subdivision contains the same chemical constituents as the whole mass. The smallest conceivable quantity, for instance, of formyle, consists of carbon and hydrogen. Formyle has never been produced separately, so as to be shown by itself; but chemists, on certain theoretical grounds, conclude that the carbon and the hydrogen of the formic acid exist therein in a state of special combination, as a distinct thing; so that formic acid consists not in a mutual partnership between carbon, oxygen, and hydrogen individually, but of a particular arrangement of carbon and hydrogen on the one hand -making formyle—with respect to oxygen on the other. In like manner, also, chloroform is ultimately resolvable into chlorine, hydrogen, and carbon: the formyle, to which the three parts of chlorine are adjoined, consisting of a peculiar union of two of carbon with one of hydrogen. Formyle is called, technically, a compound radical; that is, a substance resembling an element, but chemically divisible. Further remark on the radical principle of chloroform must be left to the professed chemist-and punster.

It is, however, worthy of observation that, as Dr. Simpson has pointed out, the discovery by Soubeiran, Liebig, and Dumas, of the formation and composition of chloroform, resuited from inquiries and experiments instituted by them,

with the sole object of investigating a point in philosophi cal chemistry. They had no notion, no surmise, of the wonderful agency of chloroform on the animal system. Had they been asked to what practical purpose they expected their researches would tend, they could only have answered, generally, that every addition to the stock of human knowledge is of some use or other, although we may be unable to conjecture or foresee its precise utility. Such a reply would have seemed great foolishness to those rather numerous sages of every-day life who are continually asking what is the good of this or that scientific investigation, and who would have triumphed gloriously in the fancied superiority of their common sense," if no definite and categorical answer could have been given to this sagacious demand of theirs, in reference, as they, perhaps, would facetiously have said, to Chlori-and-ter-fomo-what-d'ye-callit.

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There are several methods of obtaining chloroform; the best is that of distilling a mixture of rectified spirit of wine, water, and chloride of calcium. Four pounds of the last-named substance are mingled, in a large retort or still, with twelve pounds of water, and twelve ounces of spirit, and distilled as long as a dense liquid, which sinks in the water that it comes over with, is produced. This is chloroform-in the rough. It is rectified by re-distillation at the temperature of boiling water, freed from moisture by digestion with chloride of calcium, and finally distilled with sulphuric acid. Its purity is indicated by perfect trans parency and want of color. The admixture of water would give it a milky appearance; the presence of chlorine, a yel lowish tint. As chlorine is a substance most acrid ano irritating to the air-tubes, and one of which the inhalation even in a small quantity, would be fatal, it is, of course, i

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