[161] An attempt has been made by Besnou to estimate the amount of alcohol by the specific gravity. He found that a chloroform of 1·4945 gravity, mixed with 5 per cent. of alcohol, gave a specific gravity of 1·4772; 10 per cent., 1·4602; 20 per cent., 1·4262; and 25 per cent., 1·4090. It would, therefore, seem that every percentage of alcohol lowers the gravity by ·0034.
Dr. Dott, _Pharm. Journ._, 1894, p. 629, gives the following tests:--Specific gravity, 1·490 to 1·495. On allowing ½ fluid drm. to evaporate from a clean surface, no foreign odour is perceptible at any stage of the evaporation. When 1 fluid drm. is agitated with an equal volume of solution of silver nitrate, no precipitate or turbidity is produced after standing for five minutes. On shaking up the chloroform with half its volume of distilled water, the water should not redden litmus-paper. When shaken with an equal volume of sulphuric acid, little or no colour should be imparted to the acid.
§ 175. The ordinary method of manufacturing chloroform is by distilling alcohol with chlorinated lime; but another mode is now much in use--viz., the decomposition of chloral hydrate. By distilling it with a weak alkali, this process yields such a pure chloroform, that, for medicinal purposes, it should supersede every other.
§ 176. =Statistics.=--Falck finds recorded in medical literature 27 cases of poisoning by chloroform having been swallowed--of these 15 were men, 9 were women, and 3 children. Eighteen of the cases were suicidal, and 10 of the 18 died; the remainder took the liquid by mistake.
§ 177. =Local Action of Chloroform.=--When applied to the skin or mucous membranes in such a way that the fluid cannot evaporate--as, for example, by means of a cloth steeped in chloroform laid on the bare skin, and covered over with some impervious material--there is a burning sensation, which soon ceases, and leaves the part anæsthetised, while the skin, at the same time, is reddened and sometimes even blistered.
§ 178. Chloroform added to blood, or passed through it in the state of vapour, causes it to assume a peculiar brownish colour owing to destruction of the red corpuscles and solution of the hæmoglobin in the plasma. The change does not require the presence of atmospheric air, but takes place equally in an atmosphere of hydrogen. It has been shown by Schmiedeberg that the chloroform enters in some way into a state of combination with the blood-corpuscles, for the entire quantity cannot be recovered by distillation; whereas the plasma, similarly treated, yields the entire quantity which has in the first place been added. Schmiedeberg also asserts that the oxygen is in firmer combination with the chloroformised blood than usual, as shown by its slow extraction by stannous oxide. Muscle, exposed to chloroform liquid by arterial injection, quickly loses excitability and becomes rigid. Nerves are first stimulated, and then their function for the time is annihilated; but on evaporation of the chloroform, the function is restored.