CHLOROFORM (trichlor-methane), CHC13  , a valuable an-aesthetic, a colourless liquid, possessing an agreeable smell and a pleasant taste . It may be prepared by the action of bleaching powder on many carbon compounds, such, for example, as ethyl alcohol and acetone (E . Soubeiran, Ann. chim. phys., 1831 [2], 48, p . 131; J . V . Liebig, Ann., 1832, 1, p . 199), by heating chloral with alkalis (Liebig), CCI3CHO + NaHO= CHCI3 + NaHCO2, or by heating trichloracetic acid with ammonia (J . Dumas, Ann., 1839, 32, p . 113) . In the preparation of chloroform by the action of bleaching powder on ethyl alcohol it is probable that the alcohol is first -oxidized to acetaldehyde, which is subsequently chlorinated and then decomposed . Chloroform solidifies in the cold and then melts at -62 C.; it boils at 61.2° C., and has a specific gravity 1.52637 (0 /4°) (T . E .

Thorpe) . It is an exceedingly good solvent, especially for fats, alkaloids and iodine . It is not inflammable . The vapour of chloroform when passed through a red-hot tube yields hexachlorbenzene C6C16, .perchlorethane C2CI6i and some perchlorethylene C2C14 (W . Ramsay and S . Young, Jahresberichte, 1886, p . 628) . Chromic acid converts it into phosgene (carbonyl chloride, COC12) . It reacts with sodium ethylate to form ortho-formic ester, CH(OC2H5)3, and when heated with aqueous ammonia for some hours at 200-220° C. gives carbon monoxide and ammonium formate, 2CHCI3 + 7NH3 + 3H2O = NH4•HCO2 + CO+6NH4C1 (G . Andre, Jahresb., 1886, p . 627) . When digested with phenols and caustic soda it forms oxyaldehydes (K .

Reimer, Ber., 1876, 9, p . 423); and when heated with alcoholic potash it is converted into

potassium formate, CHC13 + 4KHO=KHCO2 + 3KC1+ 2H20 . It combines with acetoacetic ester to form the aromatic compound meta-oxyuvitic acid, C6H2•CH3.OH•(COOH)2 . A hydrate, of composition CHC13.18H2O, has been described (G . Chancel, Fresenius Zeitschrift f. anal . Chemie, 1886, 25, p . 118) ; it forms hexagonal crystals which melt at 1.6° C . Chloroform may be readily detected by the production of an isonitrile when it is heated with alcoholic potash and a primary amine; thus with aniline, phenyl isocyanide (recognized by its nauseating smell) is produced, CHCI3+C6H 5N H2+3KHO = C6H 5NC+3KCI+3H20 . For the action and use of chloroform as an anaesthetic, see ANAESTHESIA . Chloroform may be given internally in doses of from one to five drops . The British Pharmacopoeia contains a watery solution—the Aqua Chloroformi—which is useful in disguising the taste of nauseous drugs; a liniment which consists of equal parts of camphor liniment and chloroform, and is a useful counter-irritant; the Spiritus Chloroformi (erroneously known as " chloric ether "), which is a useful anodyne in doses of from five to forty drops; and the Tinctura Chloroformi et Morphinae Composita, which is the equivalent of a proprietary drug called chlorodyne . This tincture contains chloroform, morphine and prussic acid, and must be used with the greatest care .

Externally chloroform is an antiseptic, a

local anaesthetic if allowed to evaporate, and a rubefacient, causing the vessels of the skin to dilate, if rubbed in . Its action on the stomach is practically identical with that of alcohol (q.v.), though in very much smaller doses . The uses of chloroform which fall to be mentioned here are:—as a counter-irritant; as a local anaesthetic for toothache due to caries, it being applied on a cotton- VI . 9CHM IELNICKI 257 wool plug which is inserted into the carious cavity; as an antispasmodic in tetanus and hydrophobia; and as the best and most immediate and effective antidote in cases of strychnine poisoning .