162 



PROCEEDINGS OF THE AMERICAN ACADEMY 



After the tare had thus been takeu, the globe was removed from 

 the balance, placed in the protecting case, and filled with hydrogen as 

 just described. The inlet tube, to which a rubber connector had been 

 attached, was scrupulously cleaned as before, and the globe was again 

 dusted and hung on the balance. During all these transfers the globe 

 was always handled with clean cotton cloth, and the hands never came 

 in contact with the glass. The increased weight was now the weight 

 of the hydrogen ; and as the volumes equipoised were exactly the 

 same, and the additional weight was represented by less than five 

 tenths of a gram of platinum, any correction for the buoyancy of the 

 atmosphere is unessential. 



Combustion Apparatus. 



The apparatus by which the combustion of the hydrogen was made 

 is represented in the Plate accompanying the paper (Fig. 6). It is made 

 up of a series of small combustion furnaces, which are a modification 

 of a kerosene-oil stove called " the American," very much used in the 

 United States. This stove, as adapted to chemical uses by the writer, 



is shown in Figs. 2 and 3, and it has 

 proved of great value, not only for ele- 

 mentary chemical experiments in school 

 courses, where illuminating gas is not 

 to be had, but also iu a well equipped 

 chemical laboratory. The stove is 

 made for burning kerosene oil, but 

 alcohol can also be burnt in it with 

 decided advantage for chemical work. 

 The figure of the stove has been drawn 

 to about one sixth of the actual size. 



In the figure of the combustion ap- 

 paratus (Fig. 6, Plate) it will be no- 

 ticed that the globe, protected by its 

 case, stands about in the middle of the 

 line. By means of a suction pump 

 attached to the extreme right of the 

 apparatus, a current of air is main- 

 tained through the whole length. Beginning now at the extreme 

 left, the air first passes over reduced copper, and is deprived of its 

 oxygen. It next passes over cupric oxide, by which any traces of 

 hydrogen that had remained occluded by the reduced copper, or any 

 traces of hydrocarbons in the air itself, are burnt. It next passes 



Fig. 2. 



