W. G. Mixter — Thermochemistry of Silicon. 127 



The apparatus in which silicic acid was dissolved in hydro- 

 fluoric acid is shown in fig. 1. It is an old sterling silver 

 bomb with a new silver-plated brass top and fixtures. The 

 disc b is held in place by the rod d. The cup c, shown better 



Figs. 1 and 2. 



LaJ 



-rir-hr 



in'fig. 2, is made of thin sheet silver. The small hole in the 

 bottom'allows air to escape so that c may sink in the acid. The 

 hole is covered by a disc of silver. The silicic acid for an ex- 

 periment is placed in c which is closed by a cover not shown 

 in the figure. The weight is taken and c is at once placed in a. 

 The cover is removed and a is closed by b and the joint is made 



