1909.] Physiological Properties of Tetrachlor ethane, etc. 219 



the former value being rather higher than that of the above-named 

 writers. 



Ti'icMor ethylene. — On distillation by the method described above, the 

 following results were obtained. Bar. = 765 : — 



Per cent. 



Portion boiling below 87° (binary mixture of compound with 



water) 7"5 



Ditto between 87° and 88° 80-5 



Kesidue, very discoloured 7'5 



Loss 4-5 



100-0 



The portion boiling at 87° to 88° was allowed to stand some days over 

 calcium chloride, and then redistilled ; the main bulk of the liquid came over 

 at 87"4 + 0'l (corr.). Another sample was previously shaken up with a con- 

 centrated solution of sodium carbonate, then dried over calcium chloride and 

 redistilled; the main bulk of the liquid came over at 87'55 + 0'l (corr.). Both 

 the samples were used as pure for the purpose of experiment. 



I am indebted to Mr. Ellis for a determination of the chlorine contents ; 

 the value obtained was 99'97 of that required by theory, thus showing that 

 the method adopted for purification had been successful. 



As the statement has been made that trichlorethylene on distillatioii gives 

 off hydrochloric acid gas, the receiver in the latter operation was connected 

 with an absorption vessel, containing a definite volume of njlO sodium 

 hydroxide, but the amount of alkali neutralised by the gas evolved on dis- 

 tillation of 250 c.c. of trichlorethylene was quite insignificant. The vapour of 

 trichlorethylene, kept in a stoppered bottle and exposed to ordinary daylight, 

 gave an acid reaction, but the same applies in a less degree to chloroform. 



At present, no experiments have been conducted with a view of deter- 

 mining the relative decomposition and consequent acidity of trichlorethylene 

 and chloroform respectively of presumably the same degree of purity and 

 under identical conditions of illumination. 



The suggestion is, however, raised that the superincumbent vapour, and not 

 the liquid, in a partially filled bottle is initially decomposed. 



Determination of the density at different temperatures gave the following 

 results : — 



D^/* = 1-49 045, D"-5/"-5 = l-4702o, D^W-s = 1-45987; 



from these determinations the relative volumes in terms of that at 4° are : — 

 V4 = 1, Vn.5 = 101 28, V25.3 = 1-0209. 



