344 



The author then investigated many other practical points in the 

 use of the battery, ascertaining the influence of various circumstances 

 in the manner already described. Thus he found nitric acid to give a 

 higher result of voltaic action than sulphuric or muriatic acid; the 

 quantity of zinc dissolved in order to produce decomposition of an 

 equivalent of water being only 185 per plate when nitric acid was 

 used, 3*8 when muriatic acid was used, and 4'66 when sulphuric acid 

 was employed. The acid which he afterwards used as the best for 

 ordinary purposes consisted of 200 water, 4*5 oil of vitriol, and 4 

 nitric acid. 



The mode of proof adopted by the author was of course independ- 

 ent of the strength of the acid; as was shown by making experi- 

 ments with the same acid at very different strengths; thus, when 

 nitric acid was used, and the strengths were as 1,2, and 4, the pro- 

 portion of zinc dissolved was very nearly the same for the water de- 

 composed. The same result was obtained when sulphuric acid was 

 employed. 



The different circumstances of uniformity of charge — purity of zinc 

 —foulness of the zinc plates — new and old plates — vicinity of the 

 copper and zinc — doubling of the copper — first immersion of the 

 plates — number of plates — size of the plates and simultaneous de- 

 compositions — were then considered, and such of them as would ad- 

 mit of experimental comparison in the manner already described 

 were put to this test. 



The Society then adjourned over the long vacation, to meet again 

 on the 19th of November next. 



