Manchester Memoirs, Vol. xlviii. (1904), No. VX. 9 



thin glass rod rounded at the bottom and ground into the 

 end of the tube used for holding the suspected liquid. 

 See diagram, opposite page 10, Volume 47, of the Society's 

 Memoirs and Proceedings, and explanation therein given. 



This device is important when the cooling method is 

 being used ; the liquid can thus be run into the porous 

 jar of the apparatus without shaking or disturbing it, as 

 any shaking would displace the narrow glass tube deliver- 

 ing the cold water on to the fine drawn out portion of the 

 glass tube through which the hydrogen passes. 



The negative wire is joined to the zinc, which projects 

 through a paraffined cork, and the positive to the deep 

 band of platinum foil outside the porous jar. The 

 method for accurately determining the point at which the 

 mirror should be deposited by the cooling method is 

 described on page 6, Vol. 47, of the Memoirs of the 

 Society. If the wires have been properly joined up the 

 ozone smell emitted from the anode can be at once 

 detected. 



In order to use as little liquid as possible for con- 

 ducting the electric current to the anode the porous jar, 

 surrounded by the closely fitting platinum foil anode, is set 

 in a glass beaker, about ^^th of an inch internal diameter 

 wider than the external diameter of the porous jar ; only 

 about loc.c. of sulphuric acid (i of acid to 7 of water) being 

 used to fill the annular space between the pot and the jar. 

 This is important, as the Committee's method requires a 

 comparatively large quantity of the valuable arsenic-free 

 sulphuric acid for each test. 



The resistance of this cell is found to be about i ohm 

 as against i^ ohms for the Committee's apparatus. 



The following shews the amount of gas yielded and 

 the sizes of the hydrogen flames produced by the different 

 amperages ; — - 



