Viscosity of Hydrogen, Nitrogen, and Oxygen. 589 



to hydrogen caused the viscosity to change from 882 x JO" 7 

 to 1092 x 10" 7 — -almost 25 per cent. 



Fig. 2 shows the general arrangement of the purifying- 

 devices. The whole lead from the gas generator to the 

 chamber of the apparatus was made of glass tubes \a ith all 

 connexions made by fusion excepting the junctions between 

 the hard pyrex and the ordinary soft glass tubes, where it 

 was necessary to employ sealing-wax. 



Fij 



To other gUS 

 i generators 



To frrCZCUTS 



From the generator the gas passed through the stopcock Sj 

 into two wash-bottles, each containing a concentrated solution 

 of KOH, where all the fumes of chlorine and of the reagent 

 are absorbed. It then passed successively through two 

 pyrex tubes, one containing filings of metallic calcium while 

 the other contained granulated chemically pure copper, heated 

 by electric heaters up to about 450 degrees centigrade. The 

 calcium tube was provided for the absorption of nitrogen, 

 while the copper was for the removal of oxygen. From 

 there the gas passed through a wash-bottle containing con- 

 centrated sulphuric acid, and then through a tube containing 

 lumps of KOH, and then through a whole battery of tubes 

 containing P 2 5 . Before entering into the chamber of the 

 apparatus the gas passed through two pyrex tubes T u T a , 



