225 



tain any current from such an arrangement. A mixture of chlorate 

 of potasli and concentrated sulphuric acid formed a good charge for 

 the negative side of Grove's double cell. 



The author then proceeded to describe the platinized zinc battery. 

 He was led to its discovery by observing that zinc (not amalga- 

 mated) has a tendency to assume an inactive state in some solutions 

 containing a large quantity of sulphuric acid. Two or three arrange- 

 ments were described, in which the negative plate consisted of zinc 

 in various fluids, viz., dilute sulphuric acid, hypochloric acid and 

 sulphuric acid, solution of sulphate of copper and sulphuric acid, 

 &c. The most powerful battery of this class was formed by a ne- 

 gative plate of zinc included in a porous cell, containing a mixture 

 of one measure of nitric acid with four of sulphuric acid, and asso- 

 ciated with a double plate of zinc in a solution of potash or common 

 salt. Such a circle was found t j have an intensity equal to the bat- 

 tery of Professor Daniel, but by simply brushing the negative plate 

 with a very dilute hot or acid solution of chloride of platinum, the elec- 

 tro-motive force of the battery ivas doubled, a single cell being then 

 capable of decomposing water with platinum electrodes. A platinized 

 zinc battery of three cells was placed on the table, the arrangement 

 of the porous and outer cell being that of Professor Grove. The po- 

 sitive plate of each outer cell was folded over into the porous cell, 

 and formed the negative plate of the pair next in series ; there was 

 therefore no necessity for binding screws, solderings, or mercury 

 cups in the whole arrangement. The platinized zinc of each cell 

 exposed a surface of 25 in. by 3- 7 in. The series of three cells 

 gave a cubic inch of mixed gases in 37 seconds, but the author con- 

 sidered that the battery would give two cubic inches of gas per mi- 

 nute, when the- charge of the arrangement had become warm by the 

 passage of the current. After use, the zinc plates were well rinsed 

 in clean water and allowed to dry, and it was considered advisable 

 to give them a slight brushing with the solution of platinum before 

 their being again used. The platinized zinc battery was a conistant 

 arrangement. 



The following Donations to the Library were announced : — 



American Journal of Science and Arts. Conducted by Professors 

 Silliman and Dana. Second series. Vol. VII., No. 19. 8vo. — 

 By the Editors. 



