The Rev. N. J. Callan on a neuo Voltaic Battery. 83 



Seeing that the concentrated acids, by dissolving the lead, 

 removed the gold or platina powder, and that the nitric acid 

 was very expensive, 1 endeavoured to find in its stead a cheap 

 substitute which would not act on the lead. The first that 

 occurred to me was common nitre. I dissolved about the 

 eighth of an ounce of it in sulphuric acid, which I diluted with 

 nearly an equal bulk of water. 1 poured the mixture into 

 the porous cell of a Grove's battery, and put into it a pla- 

 tinized leaden plate. I then sent the voltaic current through 

 the helix of our large electro-magnet: the magnetic power 

 given to the magnet appeared to be greater than that which 

 was given to it by a Grove's battery of the same size, in which 

 the platina was excited by concentrated nitric and sulphuric 

 acid. I afterwards compared the heating power of the two 

 batteries, and found the power of the platinized lead battery 

 to be evidently superior to that of the other. I charged a 

 platinized leaden battery with a mixture consisting of about 

 five parts of sulphuric acid, five of solution of nitre, and one 

 of nitric acid, and a Grove's battery with equal parts of nitric 

 and sulphuric acid. The former fused a piece of steel wire 

 which the latter only raised to a white heat. When a platina 

 plate is excited by a mixture of sulphuric acid and a solution 

 of nitre, the voltaic current appears to be as powerful as that 

 which is produced by the plate when excited by concentrated 

 nitric and sulphuric acid. The cost of the nitre necessary 

 for charging a battery is about the twentieth part of that of 

 the nitric acid. The power of the former declines sooner than 

 that of the latter: but from the results of several experiments, 

 I have come to the conclusion that the expense of doing a 

 given amount of work by a platina battery excited by con- 

 centrated nitric and sulphuric acid, would be three or four 

 times as great as if the work were done by a platinized lead 

 battery excited by a mixture of sulphuric acid and a solution 

 of saltpetre. I have tried nitrate of soda, or cubic nitre, and 

 nitrate of ammonia, as substitutes for nitric acid ; but although 

 they give great power, they do not answer as well as the com- 

 mon nitre. A solution of common nitre and cubic nitre along 

 with sulphuric acid, forms a mixture scarcely inferior to the 

 solution of common nitre and sulphuric acid. The most 

 powerful mixture for the platina or platinized lead battery 

 consists of about four parts of sulphuric acid, two of nitric 

 acid, and two of a saturated solution of nitre. When no nitric 

 acid is used, at least one half of the mixture should consist of 

 sulphuric acid, and the remainder of nitre and water : the 

 solution need not be saturated with nitre. Four parts of sul- 

 phuric acid, two of a solution of chromate of potash, and two 



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