116 



PROCEEDINGS OF THE AMERICAN ACADEMY 



as in our own. The wood-cuts are taken from the catalogue of the 

 firm, who have kindly loaned the blocks for this paper ; and we would 

 here express our obligations to them for their great courtesy and lib- 

 erality during the whole course of our exjieriments. 



The apparatus consists of two parts, the generator and the fountains ; 

 and in Fig. 1 the generator is represented connected by a rubber hose 

 with one of the fountains, of which in practice we use three, connected 

 in a line by similar lengths of rubber hose, like so many Woolf's bot- 

 tles. In the figure, only the first of the line is represented, which is 

 set on trunnions in a frame, in order to facilitate the agitation of the 

 water and the gas. Only one of these frames, however, is required, 

 to which the other fountains can readily be transferred. A section of 

 the generator is represented in Fig. 2. It is made of cast iron, and in 



Fig. 2. 



two parts (readily distinguished in the figure), which are firmly bolted 

 together, so as to confine in its place the bell-metal jjlate M, which 

 separates the upper from the lower chamber. In the lower chamber is 

 placed dilute sulphuric acid, which is poured in through the bung A. 



