Miscellaneous Contributions by Dr. Hare. 



opening in the pedestal, 

 some irregular fragments 

 of glass are laid, so as to 

 furnish support to some 

 carbonate of ammonia, 

 subsequently introduced 

 into the jar. Suppose the 

 upper inverted bell, B, to 

 be supplied with a solution 

 of pearlash, and another 

 smaller uninverted bell 

 glass, C, placed within it. 

 so as to include the pipe 

 proceeding from the bell, 

 A, below. If, while the 

 apparatus is thus situated, 

 diluted nitric acid be pour- 

 ed into the cylindrical glass 

 vessel, D, it will rise into 

 the jar containing the car- 

 bonate, and cause it to 

 give out carbonic acid gas. 

 This gas will at the same 

 time press with equal force 

 upon the surface of the acid in the glass cylinder below, and 

 upon that of the alkaline solution in the upper bell C. 



If the atmospheric air of the vessel be allowed first to 

 escape by a hole at C, (closed or opened by a screw omitted 

 in the figure) so that the carbonic acid may reach the alka- 

 line solution undiluted with air, it will of course be gradually 

 absorbed, generating bicarbonate of potash. Should the 

 absorption thus arising, be too slow to take up the carbonic 

 acid as fast as it is evolved by the reaction between the acid 

 and the carbonate, the alkaline solution will be depressed 

 within the bell glass, C. At the same time the pressure with- 

 in the larger bell glass increasing proportionally, the height to 

 which the acid reaches in the jar is diminished, and of course 

 the re-action with the carbonate lessened, until the quantity 

 of carbonic acid evolved by it, be commensurate with the 

 absorption by the solution in the upper part of the appa- 

 ratus. Should the solution become saturated, the depres- 

 sion of this solution in the bell C and of the acid in the jar 

 D, must go so far. as that the acid no longer reaching any 



