592 Prof. Kia-Lok Yen on the Coefficients of 



of glass work. The NH 4 N0 3 solution was contained in the 

 pyrex flask A, which was heated np by an electric heater. 

 \Vhile thus being heated the NaN0 2 solution was caused to 

 drop into it by the manipulation of the stopcock S. The 

 gas thus generated was passed through the flask B, which 



Fig. 3. 



contained a superheated solution of potassium dichromate 

 dissolved in concentrated nitric acid, then through a wash- 

 bottle containing concentrated sulphuric acid, then a tube 

 containing lumps of KOH, and then two pyrex tubes, 

 one containing granulated copper and the other containing 

 powdered oxide of copper, both being heated up to about 

 450 degrees centigrade. Thereafter the gas passed through 

 a battery of P 2 Oo tubes and then through a coil T before it 

 entered the compression-and-suction apparatus C (in fig. 2) 

 through the stopcock S 7 . The tube V was provided for the 

 spectral examination of the gas. The stopcocks S x to S 6 

 were shunt passages as previously described and were 

 always closed except when the apparatus was being 

 evacuated- The process of filling the chamber was the 

 same as that in the case of hydrogen. 



