August 11, 1911] 



SCIENCE 



169 



throw light on, if not fully explain, the 

 role of alcohol^" and other substances in 

 the so-called preservation of chloroform, 

 a satisfactory explanation of which has 

 been wanting. 



Various samples, some twenty-three in 

 all, of both pure chloroform^^ and chloro- 

 form containing the u^ual pharmacopoeial 

 amounts of alcohol and water, were ex- 

 posed, in well-stoppered^^ containers of 

 various sizes, and containing varying 

 amounts of the samples, and of both color- 

 less and anaetinic glass, such as are cus- 

 tomarily used in the trade, for different 

 periods of time, but at room temperature 

 (20° C), from September to May, inside 

 of a window having direct southern ex- 

 posure. The conditions were extreme, but 

 nevertheless were similar to those obtain- 

 ing in many pharmacies and hospitals. 



The anesthetic chloroform used was ex- 

 amined prior to the experiments, and only 

 such chloroform as was found to be free 

 from impurities was used. However, an 

 amount of water equivalent, on the aver- 

 age, to 5.1 per cent, by volume of the alco- 

 hol present was permitted.^^ Thus each 

 sample was of pharmacopceial grade. 



" The amounts of alcohol stated as permissible 

 in the various official chloroforms intended for 

 anesthetic purposes are as follows: 



Belgium 1.0 per cent. 



Denmark 1.0 per cent. 



Sweden 0.5-1.0 per cent. 



United States 0.6-1.0 per cent. 



France 0.005 part by weight. 



Italy 0.5 per cent. 



Switzerland 1.0 per cent, absolute. 



" This chloroform was prepared according to 

 the method of Baskerville and Hamor and was 

 absolutely pure. 



^ No cork stoppers unprotected by metal caps 

 were employed. In the experiments on pure chlo- 

 roform, glass-stoppered bottles were solely used. 



"The alcohol content of the anesthetic chloro- 

 form used was determined quantitatively by the 

 method of Nicloux. 



The tests applied for the detection of the 

 oxidation products of chloroform and alco- 

 hol were those previously proved out in 

 our work. Quantitative determinations 

 of the impurities developed were made 

 when possible. 



The experimental results warranted the 

 following conclusions : 



1. The products of the oxidation of 

 pure chloroform are carbonyl chloride and 

 hydrochloric acid, which come about ac- 

 cording to these reactions : 



CHa3 + H,0 -1- O, = COCl, -j- HCl -I- mo^; 

 CHCI3 -f HA = COCl, -I- HCl + H2O. 



We are convinced that oxidation will 

 not occur if water be excluded, and the ab- 

 solute exclusion of moisture appears to be 

 impossible. Hydrogen dioxide is formed, 

 although we have been unable to detect it 

 in chloroform undergoing oxidation, and 

 therefore conclude that its existence is 

 ephemeral, and oxidation of the chloro- 

 form continues throughout the period of 

 exposure. The role of the water is that of 

 a true chemical catalyst. The decompo- 

 sition of pure chloroform is accelerated by 

 light, and carbonyl chloride is formed with 

 increased readiness in the presence of 

 acids. ^* 



The extent of the oxidation is dependent 

 upon the nature of the container, the 

 amount of air present, the purity of the 

 sample, and the intensity of the light to 

 which it is exposed. 



Free chlorine can only result from the 

 photochemical decomposition of carbonyl 

 chloride :^^ 



" Cf . Lowry and Magson, Trans. Cliem. Soc, 93, 

 121, who observed that the formation of carbonyl 

 chloride is evidently accelerated by the presence 

 of acids. 



■° In this connection, see Coehn and Decker, 

 Ber., 43, 130; and Weigert, Ann. PhysiJc, 1907, 

 (4), 24, 55. The influence of light on the re- 

 versible reaction, CO +' CI2 ?± COCl™, is purely 

 catalytic. 



