166 



SCIENCE 



[N. S. Vol. XXXIV. No. 867 



tions in short intervals during storage in 

 glass vessels, just as in the case of the oxi- 

 dation of ether itself. The variations in 

 acidity — theoretical, but not sensible in 

 general — may be due to differences be- 

 tween the rapidity of the oxidation and 

 the saturation of the acids by the bases of 

 the glass. In fact, it should be mentioned 

 here that the nature of the ether container 

 is of vast importance in the light of the 

 oxidation changes which are possible. The 

 extent of the oxidation — or, for that 

 matter, any oxidation at all — ^is dependent 

 upon the quality of the glass used in bot- 

 tles for storing ether; and in the case of 

 metallic containers, in view of some recent 

 researches, it is probable that all metals 

 which show anomalous anodic conductiv- 

 ity are likely to develop free hydrogen 

 dioxide in contact with water and oxygen. 

 The presence of such metals should, there- 

 fore, be guarded against. 



Since it is highly important that ether 

 intended for anesthetic purposes should 

 be carefully manufactured and properly 

 stored, as prolonged exposure to light and 

 air greatly affect the results of etheriza- 

 tion, causing coughing, suffocation, and 

 even dangerous after effects, such ether 

 should always be tested for peroxides and 

 aldehyde, and the presence of the latter 

 should be rigorously guarded against, or 

 the ether, if so contaminated, should be 

 administered by a method which elimi- 

 nates these impurities before it is intro- 

 duced into the animal system. 



We have made an examination as to the 

 value of all proposed tests for the pres- 

 ence of impurities in ethyl ether, and have 

 devised several new and superior ones. A 

 scheme for examination has been worked 

 out and is now available in the literature.'^ 



CHLOROFORM 



Liebig prepared chloroform from 

 ' Baskerville and Hamor, loo. cit., 3, No. 6, p. 395. 



chloral. Soubeiran treated alcohol with 

 "bleaching powder." Schering generated 

 his "bleach" in the presence of alcohol by 

 electrolysis. Then commercial methyl alco- 

 hol was used and "methylated spirit," 

 whereby so-called "methylated chloroform" 

 was obtained. Liebig also obtained chloro- 

 form by the action of "chloi-ide of lime" 

 upon acetone. Bottger and others used 

 acetates (1848), and then chlorine was 

 liberated in acetone by electrolysis. This 

 process is used extensively in this country 

 now. Methane of natural gas has been 

 burned in chlorine, but this process has not 

 proved successful commercially so far, al- 

 though "gas chloroform" is spoken of by 

 some in a wise way. Carbon tetrachloride, 

 made by chlorinating carbon disulphide, is 

 being reduced by the process of Smith to 

 produce much chloroform in this country 

 at present. "Chloral chloroform" is im- 

 ported in small quantities. 



From the variety of "Ausgangs-mater- 

 ial" and different methods used it is quite 

 evident that crude chloroform may con- 

 tain a wide range of impurities, which may 

 vary not only with the materials used but 

 also with the conditions of manufacture. 

 Alcohol has been removed from chloroform 

 by washing with water, the chloroform 

 being subsequently dried over calcium 

 chloride. Potassium hydroxide has been 

 used to remove excess chlorine and acids. 

 Manganese dioxide has been employed to 

 remove sulphur dioxide. Chloroform has 

 been shaken with concentrated sulphuric 

 acid until the acid was no longer colored; 

 the vapors of chloroform have been passed 

 through towers of crystallized sodium car- 

 bonate after treatment with sulphuric 

 acid, and rectification has followed. To 

 remove special impurities or decomposi- 

 tion products of the chloroform itself, 

 chloroform has been treated with lead di- 

 oxide; with potassium permanganate, or 



