Considerable attention has been directed to different methods of administering chloroform, and various forms of apparatus have been devised which claim to reduce to a minimum the dangers of anæsthesia. Assuming a most skilled and competent administrator, an ideal method of administration, and a suitable patient, an unsatisfactory result can only be attributed to the chloroform employed. Purity of chloroform is a most important factor in contributing to safe anæsthesia. The physician claims that absolute purity shall characterise all medicinal agents, and the justice of the claim is acknowledged by the trend of recent legislation. Purity is a prime essential of any anæsthetic. The presence of impurities largely increases the risk inseparable from the use of chloroform. The train of symptoms observed during the normal process of anæsthesia may be masked and altered, and dangerous results may supervene under the most competent, careful and observant administrator. [Illustration: AN OPERATION IN THE TWENTIETH CENTURY] [Sidenote: Expert testimony] That some of the chloroform offered to the profession may reasonably be regarded with suspicion is evidenced by the words of a prominent obstetrician, based on the experience of 40 years in the use of chloroform; this authority expresses himself as follows: “I may say I fear the chloroform in common use is often far from being as pure as it should be, and is sometimes very defective in this respect.” [Sidenote: Effects of impurities] Impurities may result from the process of manufacture, or from decomposition. Conspicuous amongst these undesirable elements are chlorine, hydrochloric acid and carbonyl chloride (phosgene), which irritate the lining membrane of the respiratory tract and interfere with the normal process of respiration. Such irritation may result in arrest of cardiac action or may produce a severe form of bronchitis. It is obviously of great importance that chloroform should be free from irritating properties, that the respiratory passages should not be obstructed, and that during anæsthesia the breathing and the circulation should approximate the normal. Superadded to these results, produced by local irritation, is the effect of other impurities which exert their action after absorption. These latter markedly increase the cardiac depression which has been shown to follow the administration of pure chloroform. Such an action is difficult of detection, and is, probably, in large degree responsible for a considerable number of the accidents reported. [Sidenote: Contradictory results] [Sidenote: Recent research] [Sidenote: Ethyl chloride]