224 



variety of solutions, he was led to consider mixtures of chromic or 

 chlorous acid with dilute sulphuric acid, best adapted to the purpose 

 he had proposed. 



The chromic acid battery was arranged by twisting round one end 

 of a cylinder of coke a copper conducting wire, soaking the part in 

 boiling wax, and afterwards covering it with varnish, to protect the 

 wire from the acid : the coke was then surrounded by a cylinder of 

 amalgamated zinc, and firmly fixed in its place by wedges of var- 

 nished cork. To form the exciting liquid, a measure of strong sul- 

 phuric acid was added to an equal measure of a hot saturated solu- 

 tion of bichromate of potash : the mixture was then diluted with four 

 measures of water, and set aside to cool. The coke and zinc cylin- 

 ders placed in a tumbler of the solution possessed a high degree of 

 electro-motive force, a single alternation being capable of decompos- 

 ing acidulated water with platinum electrodes. The author stated, 

 that the arrangement was not constant, its action gradually declining 

 after immersion. But he considered that a small pair was well 

 adapted for the excitation of electro-magnetic apparatus, from its 

 possessing about three times the intensity of Smee's arrangement. 

 In an experiment made by him with Dr Wilson, a series of four 

 pairs, roughly put together in half-pint tumblers, decomposed acidu- 

 lated water, at the rate of two cubic inches of mixed gases per mi- 

 nute with a cold, and four with a hot, charge of the chromic acid 

 solution. No gas was evolved from the amalgamated zinc surface 

 in either case. One of the advantages of the battei-y was, that a 

 series of cylindei's, however extensive, might, as in Wollaston's ar- 

 rangement, be immersed and removed from the solution at once, and 

 the energetic effects of ^first immersion obtained at pleasure. Platina, 

 or boxwood charcoal might be used in place of coke : a small series 

 of thirteen pairs (charcoal and amalgamated zinc), each exposing a sur- 

 face of about a quarter of an inch square, afforded a shock equal to 

 a Cruickshank's battery of fifty pairs of four-inch plates, a perceptible 

 shock being even felt from four pairs. 



The solution of chlorous or hypochloric acid (CI O4) was prepared, 

 by pouring a drachm of powdered chluiate of potash into a wine 

 glass containing an ounce of concenti'ated sulphuric acid, and in ten 

 minutes afterwards plunging the mixture into seven ounces of water. 

 A pair of plates (amalgamated zinc and thin sheet-brass) excited by 

 the last solution gave a powerful current, until the chlorous acid was 

 exhausted. The author had, however, more than once failed to ob- 



