Mr. Grove on the Gas Voltaic Battery. 



423 



immersed in separate vessels of dilute sulphuric acid, and 

 filled with atmospheric air exactly to the extreme graduation ; 

 the water mark within the tube was examined when exactly at 

 the same level as the exterior surface of the liquid ; folds of 

 paper were used to protect them from the warmth of the 

 hands, and thus prevent expansion ; the barometer and ther- 

 mometer were examined, and every precaution taken for ac- 

 curate admeasurement. One of these tubes was left empty in 

 order to ascertain, and eliminate from Fig. 12. 



the result, the effect of solubility. Into « 



the other was placed a strip of platinized 

 platinum foil, one quarter of an inch 

 wide. This strip of foil was connected 

 by a platinum wire with another strip 

 placed in a tube of hydrogen and in- 

 serted in the same vessel. The appa- 

 ratus is shown in fig. 12. After the 

 circuit had been closed for two days, 

 the liquid was found to have risen in 

 the tube a twenty-two parts out of the 

 100 ; in the tube placed by its side, it 

 had risen one division. The tubes 

 were allowed to remain several days 

 longer, but no further alteration took 

 place. This analysis gives therefore 

 twenty-one parts in 100 as the amount 

 of oxygen in a given portion of air. 



Experime?it25. — The tube a (fig. 12) 

 was charged with nitrogen to a given 

 mark, and 0*5 cubic inch of pure hydrogen added, the tube h 

 was then charged with oxygen, and the circuit closed. Exa- 

 mined after twenty-four hours, the water had risen in the tube 

 a exactly 0\5 cubic inch. The apparatus was left in this state 

 for several days, but without any further effect; the voltaic 

 action had thus perfectly exhausted the hydrogen and there 

 stopped. 



These experiments are sufficient to prove the accurate eu- 

 diometric action of the gas battery ; performed on a large scale 

 this method of eudiometry appears to me likely to possess 

 some advantages. In the eudiometer of Volta, when gases 

 containing oxygen are to be analysed, if the hydrogen added 

 for detonation be impure, the result is of course erroneous. 

 The same may be said of the detonation by spongy platinum, 

 or by a wire heated by a voltaic current, which I formerly 

 proposed*". 



» Phil. Mag., August 1841, p. 99. 



