Intelligence and Miscellaneous Articles. 389 



sulphuric acid and deutoxide of manganese. The author employed 

 several coke elements cut from the same piece in order that the 

 porosity and conducting power might be the same ; he had as many 

 porous cells, and introduced the pieces of coke successively into 

 the same Bunsen's element, the carbon being inside, and the sur- 

 rounding zinc perfectly amalgamated ; he took care to operate with 

 acidulated water of a constant strength. With these precautions he 

 ascertained — 



1. That the effect of deutoxide of manganese mixed with concen- 

 trated sulphuric acid and employed at ordinary temperatures, is not 

 to be compared with that of nitric acid, and that it does not sensibly 

 increase the production of electricity due to the solution of the zinc ; 

 the sulphuric acid contained in the porous cell acts merely as a 

 conductor. The author has verified the latter fact by employing 

 alternately a cell filled with the mixture and one containing only 

 sulphuric acid. 



2. When the mixture has been left several hours, it is then put 

 into the pile ; a current almost as energetic as that produced by nitric 

 acid is observed just at first ; but the intensity of this current rapidly 

 decreases, and in ten minutes, or a quarter of an hour at the utmost, 

 it is as weak as already stated. 



This arises from the mixture disengaging oxygen only very slowly 

 at ordinary temperatures ; when left to itself, the oxygen accumu- 

 lates, so that in this case the apparatus acts like a gas battery ; but 

 as soon as all the free oxygen is consumed, the production of elec- 

 tricity is only supported by that which is slowly disengaged. 



3. From this it appears, that if the disengagement of oxygen 

 could be increased, the current produced would be much more 

 energetic. This is most simply effected by an elevation of tempe- 

 rature, which the author proposes to produce by placing his battery 

 in a vessel of boiling water ; a thermometer placed in the battery 

 shows the temperature. He found that towards 140° F. the inten- 

 sity of the current increased very rapidly, and that the maximum 

 was at about 167° F. Some bubbles of oxygen are disengaged from 

 the mixture. The current thus obtained is more energetic than that 

 produced by nitric acid. It is consequently only by an elevation of 

 temperature that this mixture can furnish a sufficient quantity of 

 electricity ; it may be observed also, that, in proportion to the aug- 

 mentation of temperature, the conductibility of the fluids diminishes 

 the internal resistance. 



This process is only applicable on a large scale. The author 

 proposes the following as more convenient. Starting with the sup- 

 position that M. Guignet's experiments were made with coke cylin- 

 ders which had already been used, and to which, in consequence, 

 some nitric acid still adhered, he soaked a cylinder in nitric acid and 

 then plunged it into a cell filled with concentrated sulphuric acid. 

 The current produced was more energetic than with pure nitric acid. 

 The advantage to be obtained by the employment of sulphuric acid 

 results, consequently, from the fact, that by its avidity for water it 



