424 Mr. Grove on the Gas Voltaic Battery. 



If, on the other hand, gases containing hydrogen are to be 

 analysed, errors may result from any impurities in the oxygen 

 which is added, or from inaccuracy in the measurement of 

 either gas ; in the electrolytic method of eudiometry, the 

 quantity or purity of the hydrogen, in the one case, is of no 

 importance, and in the other, the quantity or purity of the 

 oxygen, that is, provided there be sufficient to exhaust the 

 equivalent to be abstracted from the mixed gas subjected to 

 eudiometry. 



It should be observed, that in these experiments only a 

 single pair of the gas battery can be used, as, if more be em- 

 ployed, the electrolyte is likely to be decomposed, and gas 

 added to the compound*. The process is rather slow, but I 

 think very sure. Another valuable application of this process 

 is, that it affords (in experiment 24) a simple method of ob- 

 taining nitrogen of unquestionable purity. I know of no 

 method which effects this object so perfectly. All the oxygen 

 of the air is abstracted, as well as that free oxygen which may 

 be contained in the liquid ; and by subsequently introducing 

 a little lime-water into the tube «, the trifling quantity of car- 

 bonic acid may be removed, or the same thing may be at once 

 effected by using caustic potash as the electrolyte in the appa- 

 ratus fig. 12. 



Probably many other applications of the gas battery may 

 suggest themselves to other experimentalists, and obviously 

 many more changes may be rung upon the gases employed, 

 and curious and valuable results obtained; I have, however, 

 in this paper given a sufficient number of experiments fairly 

 to open the subject ; each appears so suggestive of new ones 

 that it is difficult to know where to stop. 



The experiments on eudiometry, which 1 have last named, 

 induced me to refer to Dr. Henry's paper on Gaseous Ana- 

 lysis f 5 and on reading it I was struck with a coincidence be- 

 tween the action of spongy platinum on mixed gases and the 

 gas battery, a coincidence strongly confirmatory of the views 

 which led me to its discovery. I will endeavour briefly to 

 state these, and I state them, not as being absolutely correct, 

 for differences of opinion may exist on this as on every other 

 scientific matter, but as being those which existed in my mind 

 prior to the experiments, and which are considerably, and to 

 me unexpectedly, strengthened by the results embodied in the 

 above-mentioned paper of Dr. Henry. 



My original deduction may be stated and exemplified as 

 follows: — When pure or amalgamated zinc is immersed in 

 acidulated water, the oxygen, as is well known, will not com- 

 * See Postscript. f Philosophical Transactions, 1 824. 



