SPECIFIC HEATS OF SOME COMPOUND GASES. 583 
§ 13. Sulphuretted Hydrogen (HS). 
The gas was prepared by warming antimony sulphide with hydrochloric acid. It 
was washed with water, and dried by being passed over calcium chloride. 
An experiment to determine the deviation of the gas from Boyie’s Law gave the 
following result :— 
Taste XXVI. 






at v. | p. pr|T. 
| 291°8 38°67 967'8 1282 
| 49°8 75465 | 128°7 
64:07 587°85 129-0 
| | 85:12 443°05 129°2 
| | 102°2 369°5 129°4 

These numbers give ‘011 as the value of = ee at 760 millims. 
The theoretical density 1°177 is used in the calculation of y. 
Three determinations of the velocity of sound at atmospheric pressure give the 
following results :— 
Taste XXVIII. 








| ] 
1a 
| ’ t 1. 1 | ps 1 + Dp Sep: Oy B 
| | | | | 
| 17-8 43:31 | 48-78 V7 | 1-011 | 1391 | 
18 | 4346 | 48:85 | ne | sil 1322 
E18 43-42 48-83 1-321 
| WMigem 4 1321 1-165 

§ 14. Ethyl Formate (HCOOC,H;). 
The ethyl formate used in the experiments was allowed to stand over anhydrous 
carbonate of potash and calcium chloride, and was then fractionated. This treatment 
made the boiling-point steady, but the substance is so readily decomposed, that the 
operation had to be repeated at times, and consequently the material used was not 
the same in all the experiments. 
Every precaution was taken to keep the apparatus thoroughly dry inside and so 
prevent decomposition; but in spite of this the vapour-density results were not 
concordant enough to give a trustworthy curve. Hence it was necessary to make a 
determination of the relative densities. 
