30 ADAMS AND WILLIAMSON : PHYSICAL CONSTANTS OF MUSTARD GAS 



were made to recover it in sufficient purity from the crude product 

 with the view of preparing a sample for analysis. 



Recovery by distillation was first tried in the following way: 

 The crude product was put in a copper tube which was closed at 

 one end and which fitted inside a similar tube of siUca glass. 

 These tubes were placed in an electric furnace and heated about 

 three hours at 800 ° while the other end of the tube was connected 

 ■vvith a vacuum pump and cooled. When taken apart no change 

 could be observed. 



The same experiment was repeated at approximately 975°. 

 It was now necessary to run the pump constantly as an evolu- 

 tion of gas was taking place. On taking the apparatus apart 

 metallic sodium was found in the cold portion of the tube. In- 

 asmuch as the crude product usually contains sodium carbonate, 

 the following reaction probably took place: 



NazCOa + 2C = 2Na + 3CO 



Microscopical examination of the crude product in the tube 

 showed that the substance in question still remained. Thus 

 distillation appears not to be a suitable method for its separa- 

 tion. 



According to Bucher,^ sodium cyanide can be easily distilled 

 out of his briquets at a temperature even below 800°. These 

 experiments therefore substantiate the microscopical evidence 

 that the samples of the crude product examined do not contain 

 any appreciable amount of sodium cyanide. 



The investigation of the chemical nature of the substance in 

 question is being continued. 



PHYSICAL CHEMISTRY.— 5ow^ physical constants of mustard 

 "gas." Leason H. Adams and Erskine D. Williamson, 

 Geophysical Laboratory, Carnegie Institution of Washington. 



Some time ago it was desired, for military purposes, to know 

 the compressibility of so-called mustard gas. Accordingly, the 

 necessary measurements were carried out at this laboratory, 



^ IyOC. cit., p. 246. 



