124 



PROCEEDINGS OP THE AMERICAN ACADEMY.. 



passed over phosphoric anhydride in tube 11 directly into the bottling 

 tube. With stop-cock 12 closed and 4 open, the nitrogen of necessity 

 bubbled through bromine in the small flask 5 ; beyond this flask, if stop- 

 cock 9 were open, the gases passed directly over phosphoric anhydride in 

 10 to the cobalt bromide ; if stop-cock 9 were closed, the nitrogen and 

 bromine together passed into the flask 6, containing hydrobromic acid 

 and red phosphorus, thence into the U tube 7, containing beads moist- 

 ened with hydrobromic acid and red phosphorus, thence over anhydrous 



^ B 



Fig. 3. Apparatus for Igniting Cobaltous Bromide in any desired 



MIXTURE OF Gases. 



The use of rubber wns confined to t!.e first part of tins train, where it could do 

 no harm. (A B C D E F and A M N O P). 



calcic bromide in the tube 8 to remove the water taken from the hydro- 

 bromic acid, and finally over phosphoric anhydride in 10 to the bromide 

 of cobalt. Dry air was prepared by passing a current of air through 

 several columns of beads (OP in the figure) moistened with sulphuric 

 acid, and then into the apparatus through the stop-cock 14. The pres- 

 sure of the sulphuric acid in the bulb 3 prevented any air from back- 

 ing up into the sulphuric acid columns delivering nitrogen. In order to 

 prevent the slightest admixture of hydrobromic acid with the dry air 

 used to wash out the apparatus at the conclusion of the operation, a 

 slight excess of pressure was always maintained within the apparatus. 

 This excess of pressure was so regulated as to cause a part of the pure 



