August 11, 1911] 



SCIENCE 



167 



with dilute sodium tliiosulpliate ; or it has 

 been distilled over 2 per cent, paraffin or 

 poppy oil. "Chloroform Anschiitz" is 

 obtained by distilling from crystals of 

 salicylid-chlorof orm. ' ' Chloroform Pie- 

 tet" is made by chilling chloroform to 

 — 80° C, filtering off the solids produced, 

 and then lowering the temperature to 

 — 82° C. and drawing off the 'liquid im- 

 purities. The frozen chloroform is then 

 fractioned, the intermediate 80 per cent, 

 of the distillate being taken. 



The specific gravity values of chloro- 

 form have been determined by different 

 workers as follows:^ 



density permitted by the pharmacopoeia. 

 The samples of chloroform of German 

 manufacture examined varied in specific 

 gravity from 1.487 to 1.492 at 15/15°, al- 

 though one sample possessed a density of 

 1.497 at this temperature. Since the cor- 

 rect specific gravity of chloroform is 

 1.49887 at 15/4°, those officials requiring 

 chloroform of a lower density — that is, 

 anesthetic chloroform — allow the addition 

 of alcohol, and consequently the presence 

 of small amounts of water; the permis- 

 sible addition usually varies from 0.5 to 

 1 per cent. 



Specific gravity determinations are not 



In the course of an investigation on the 

 decomposition of chloroform, we prepared 

 pure chloroform.^ This possessed a den- 

 sity of 1.49887 at 15/4° (average of six 

 determinations), a result in close agree- 

 ment with the values of Thorpe and Tim- 

 mermans. This value may be taken as the 

 correct specific gravity at the temperature 

 noted. 



The anesthetic chloroform on the Amer- 

 ican market varies in specific gravity 

 from 1.4730 to 1.4827 at 25/25°, usually 

 in close proximity to 1.476, the minimum 



* A discussion of these values is given in an 

 elaborate paper on "Chloroform" by the speaker 

 and W. A. Hamor, which will appear in J. Ind. and 

 Eng. Cliem., 3, No. 10. 



" Baskerville and Hamor, loc. cit. 



to be regarded as criteria of purity be- 

 yond indicating the amount of alcohol in 

 chloroform. 



The boiling points of chloroform accord- 

 ing to different observers are as follows : 



BOILING POINT OP CHLOEOPOEM 



Year Observer Temperature 



1883 SchifE 60.9° at 754.3 mm. 



1884 Perkiu 62.0° at 760 mm. 



1885 Bauer 61.0° at 760 mm. 

 1889 Thayer 61.6° at 760 mm. 

 1899 Pettit 61.97° at 760 mm. 

 1904 "Wade and Finnemore 61.15° at 760 mm. 

 1911 Baskerville & Hamor 61.20° at 760 mm. 



In general, it may be said that no spe- 

 cific directions are given for the determi- 

 nation of the boiling point and the influ- 

 ence of the variables (alcohol and water 



