Chloroform (synonymes, trichlormethane, dichlorinated methyl chloride, and perchloride of formyl), a transparent, colorless oily liquid, discovered in 1831 by Samuel Guthrie of Sack-ett's Harbor, N. Y., and described by him as "a spirituous solution of chloric ether." Lie-big, in a note to an article on chloral, published in Poggendorff's Annalen for November, 1831, also mentions this compound under the name of chloride of carbon, and gives the method of its preparation. Soubeiran also discovered it independently of either of the above named chemists; and although his article appeared in the Annales de physique et de chimie for October, 1831, that number of the journal was not printed until the commencement of the year 1832, owing to the disturbed state of affairs in France at that time, and it is evident that he was not acquainted with the properties of "bichloric ether," as he calls it, so early as October, 1831. The priority of discovery in Europe is undoubtedly due to Liebig, and the confusion has arisen from the antedating of the journal in which Soubeiran's article first appeared. There is no question, however, that Guthrie was the first person to prepare chloroform, and to him the honor of its discovery is manifestly due.

It has been asserted that from the time of the discovery of chloroform by Guthrie until its application as an anaesthetic vapor, it remained a mere chemical curiosity. This is not correct. In 1831 Dr. Eli Ives, professor of the theory and practice of medicine in the medical institution of Yale college, employed chloroform in a case of difficult respiration, administering it actually by inhalation of its vapor; he afterward published the facts in the " American Journal of Science" for January, 1832. Later Dr. Nathan B. Ives employed it in asthma, and in other cases, reporting upon it favorably. The exact formula of chloroform was determined in 1835 by Dumas, who gave it its present name. It was at first regarded as formic anhydride, in which the whole of the oxygen is displaced by its equivalent amount of chlorine, and hence the name given to it by Dumas. It is now looked upon as methylic ether, in which two atoms of hydrogen are replaced by two atoms of chlorine, and its formula is CHC13. - Dr. Simpson's original paper on chloroform was communicated to the medico-chirurgical society of Edinburgh, Nov. 10, 1847, and he states that Mr. Waldie first made known the liquid to him.

The medical profession having been prepared by the success of etherization to receive any new anaesthetic, whenever properly verified, at once accepted chloroform, coming as it did from such high authority as that of the late Dr. Simpson, and the news of its revived application spread rapidly over the globe. Dr. Simpson at once communicated the results of his experiments to Dr. Charles T. Jackson of Boston, who successfully repeated the trials of its anaesthetic properties, Dec. 30, 1847, upon Charles A. Joy, at that time a pupil in his laboratory (now professor of chemistry in Columbia college, New York). The introduction of chloroform into the medical practice of the United States dates from this time, although Dr. Ives had strongly recommended it many years before. It would have been difficult to purchase an ounce of chloroform in the United States in 1847; at the present time (1873) the annual consumption in this country cannot fall much short of 100,000 lbs. - Chloroform can be obtained by the action of hypochlorite of lime (bleaching powders) upon numerous organic substances, such as wine alcohol, wood alcohol, acetone, salts of the acetates, volatile oils, acetic acid, tartaric acid, formic acid, oxalic acid, and other bodies; but the only practicable method for its production on a large scale consists in the distillation of alcohol from chloride of lime.

Six parts of chloride of lime, 24 parts of water, and one part of alcohol are mixed in a capacious still, and the temperature raised as rapidly as possible till it reaches 180° F. The distillation is then continued until about one part and a half has passed over; the products, consisting chieliy of chloroform, accompanied by water, collect in two layers in the receiver, the chloroform constituting the lower layer. It is decanted from the aqueous portion, and agitated with oil of vitriol in order to destroy traces of volatile oils which accompany it; by another rectification it is obtained in a state of purity. Chloroform is a colorless, volatile liquid, of high refracting power. It has a powerful and agreeable ethereal odor, and a sweet, penetrating taste. Alcohol and ether dissolve it in every proportion, but it is very sparingly soluble in water. Concentrated sulphuric acid has no action upon it, and even potassium does not occasion its decomposition. It is inflamed with difficulty, and burns with a greenish, somewhat smoky flame, producing hydrochloric acid as well as carbonic anhydride and water. By admixture with an alcoholic solution of potash it is decomposed, potassic chloride and formiate being produced.

Chloroform freely dissolves sulphur, phosphorus, iodine, camphor, resins, gutta percha, caoutchouc, strychnia, morphia, quinia, and fatty bodies. The specific gravity of the liquid is 1.497, of its vapor 4.2; boiling point 142° F.; it remains liquid at 0° F., but can be solidified by sudden evaporation. Chloroform vapor passed over red-hot copper is partially converted into acetylene. Pure chloroform is decomposed by exposure to light and air; but in the dark it remains unaltered in a vessel only half filled with it. - The vapor of chloroform possesses the remarkable power of producing in the person who has respired it complete temporary insensibility to pain. It may be readily inhaled for this purpose by placing a small quantity of the liquid upon a sponge or a handkerchief, which is to be held before the mouth and nostrils; and it is now commonly employed for rendering patients insensible to pain during severe surgical operations. It is of great importance that the chloroform used for this purpose should be quite pure. In some cases it has been found after exposure to a strong light to have undergone spontaneous decomposition. It ought to com-manicate no color to oil of vitriol when agitated with it.

The liquid itself should be free from color, and it should be perfectly destitute of any chlorous odor. When a few drops are allowed to evaporate on the hand no unpleasant odor should be left. At present chloroform is much more largely used than ether for the production by inhalation of surgical anaesthe-sia. It is generally admitted to have over ether the advantages of rapidity of action, convenience of administration, agreeablene^s of odor, and less subsequent nausea. These advantages, however, in the opinion of many physicians in various parts of the world, and especially of nearly all the physicians of Boston, Mass., and of Lyons, in France, are more than counterbalanced by the fact that chloroform is dangerous to life. A marked change of opinion, in favor of ether as against chloroform, has recently taken place in England. A large number of deaths from the inhalation of chloroform have occurred in the hands of the most skilful and experienced physicians. It is true that the number of deaths so produced bears a very small proportion to the total number of administrations, yet it should be remembered that only an extremely small number of deaths have ever been ascribed to the inhalation of sulphuric ether, and those perhaps incorrectly, and that the latter agent is equally efficient at the cost of a trifling inconvenience and a few seconds more time.

Deaths from chloroform take place in three ways: 1, gradual asphyxia, for which the remedy is removal of the drug and fresh air;-

2, sudden apnea or cessation of respiration, followed by asphyxia, for which the remedy is artificial respiration and the galvanic battery;

3, syncope from heart-shock, for which there is probably no remedy. Besides its use as a surgical anaesthetic, the inhalation of chloroform has been employed in midwifery, and to relieve intense pain, and to control convulsions, especially those produced by tetanus and strychnia. There is no record of death from its employment in obstetric practice in skilled hands, although there seems to be no good reason for its being safer in this department of practice than in others. Inhaled in the quantity of a few drops and largely diluted with atmospheric air, so as not to produce anaesthesia, it is used to relieve cough and irritability of the air passages. It may be administered by the stomach, combined with ether, sirup, mucilage, or glycerine, for the relief of nausea, seasickness, and nervous irritability. The writer has seen two ounces of chloroform, swallowed with suicidal intent, prove fatal in less than an hour. Applied externally, it is an irritant. Dr. Augustus Waller has shown that the admixture of chloroform greatly promotes the rapidity with which belladonna and probably other substances are absorbed by the skin.

Chloroform is also used as a solvent in the preparation and purification of alkaloids and other substances for pharmaceutical and analytical purposes. (See Anesthetics.)