CHLOROFORM (CHC1s, trichlorometh ane, methenyl chloride, terchloride of formyl), a heavy, clear, colorless, mobile and diffusible liquid of a sweet burning taste and characteris tic etheral odor formed by the action of the sun's rays on a mixture of chlorine and marsh gas; also by the action of caustic potash on chloral or chloracetic acid, or by the action of nascent hydrogen on tetrachloride of carbon. It is prepared on a large scale by distilling water and alcohol with bleaching-powder (chloride of lime). Slaked lime is sometimes added. Its vapor density is four times that of air. Its specific gravity should not be below 1.49, and it should be soluble in 200 volumes of cold water, and in all proportions in alcohol, ether, benzol, benzine and fixed and volatile oils. It is vola tile, even at low temperature, boils at 140° F. and freezes at —115° F. It should not be ex posed to the light, as it is liable to decomposi tion with the liberation of hydrochloric acid and chlorine.
As used in medicine it is a liquid consisting of 99 to 99.4 per cent by weight of absolute chloroform and 1 to 0.6 per cent of alcohol. It is not inflammable, but its vapor burns with a greenish smoky flame. It is an excellent solv ent for a variety of substances, as caoutchouc, resins, fats, sulpbue and phosphorus, many alka loids and other organic substances. It is anti septic and prevents the growth of deleterious micro-organisms, but has no effect upon yeast. Medicinally it is used as an aqua, emulsion, lin iment, spiritus and pure U. S. P. chloroform. Its physiological action is allied to the alcohols, but it is much more energetic. Externally chlo roform is an irritant, and if confined on the skin it can cause blistering. It is irritant to mucous membranes, and, taken into the stomach, causes a sense of warmth and burning with increased production of gastric secretions. In large doses it causes violent gastro-enteritis.
Its chief use in medicine is as a general anesthetic, for which purpose it was first used by Simpson, of Edinburgh, in 1848. As an anaes
thetic its vapor is inhaled; it thus enters the circulation through the blood circulating in the lungs. When so administered the stages of anesthesia closely resemble those induced by others of the alcohol series, but in chloroform the anesthesia is very rapid. There is first a stage of excitement, with heightened cerebral activities. This is soon followed by a gradual dissolution of the mental faculties, usually in an order the reverse of their complexity. Thus the highest faculties of judgment, mem ory, etc., are attacked first, then unconscious ness gradually sets in. The spinal cord centres are then affected; there may be some temporary irritation, which is followed byparalysis, and then by loss of sensation and of the reflexes. The automatic centres of breathing and the heartbeat are only slightly affected. There may be some lessening of the heart action, following an initial stimulation, and similar respiratory changes. The patient thus in complete anes thesia is motionless and senseless, unable to feel or move, his automatic functions of most vital importance to life-maintenance alone function ating. It is in this stage that operations are performed, although minor operations may be performed in the early stages of primary anesthesia.
When the administration of chloroform is pushed too far, or there is a peculiar suscepti bility to its effects, as in some individuals, poi soning results. It is usually rapid in onset, is attended with cyanosis, weak, trembling pulse and reduction of blood pressure. The vaso motor system seems to be paralyzed and death is due perhaps to this alone, although other fac tors seem to be involved at times. Following chloroform anesthesia, nausea and vomiting are apt to occur. Chloroform is a safe anes thetic, deaths to the proportion of 1:3000 or 1:4000 are said to occur; but ether, which has a proportion of 1:16,000 is preferred by many. This is so particularly in America, whereas in Europe chloroform is preferred. See ANAESTHETICS; ETHER.