42'!' Mr. Smee on the Amalgamation of Zinc. 



ode, at which oxygen is evolved, and thehydrogode, where the 

 hydrogen is given off. 



The soft and spongy charcoals, as those of deal, possess the 

 property of evolving gas very imperfectly. 



Various kinds of coal, such as anthracite and cannel, were 

 tried, but none were found to evolve hydrogen, nor to have 

 copper precipitated when the circuit was made in a solution of 

 that metal. 



From the above experiments we see that batteries niay be 

 constructed of carbon in the place of a negative metal ; the 

 hard coke or plumbago answering best, and the porous coke 

 and box-wood charcoal next *. These may be used as an 

 ordinary battery with sulphuric acid, but of course a battery 

 thus constructed possesses but little power. If, however, the 

 hydrogen is removed upon Professor Daniell's principle, then 

 will the power be increased, and a charcoal battery may be 

 made of surprising energy. The hydrogen may be removed 

 by metallic solutions which have a feeble affinity for oxygen, 

 and therefore those of gold, silver, platinum, or copper would 

 answer best -, the latter being the only one in use from its 

 cheapness. The highly oxygenated acids, such as nitric, &c., 

 are more powerful than these, and are now considerably em- 

 ployed, but disadvantages attend their action ; for if the cur- 

 rent is required to be continued for a long time, a large quan- 

 tity of acid must be used, and the fumes arising from the 

 battery are injurious to the animal oeconomy: in addition, the 

 strong acid is liable to be spilt over the fingers or clothes ; and 

 lastly, it always transudes through the porous tubes and acts 

 upon the zinc, even when amalgamated, to a considerable 

 extent. 



It is perhaps worthy of notice, that the powers of the nitric 

 acid battery are not to be attributed to the fluids alone, for no 

 current is formed when platinum is used in both cells. Strong 

 sulphuric acid produced scarcely any action, but the addition 

 of nitric acid rendered it powerful, for a time proportionate 

 to the quantity of the latter acid used. I have tried other 

 substances which have an affinity for hydrogen, such as chlo- 

 rine, iodine, chloride of lime, peroxide of iron (or a mixture 

 of muriatic acid and peroxide of manganese), so that nascent 

 chlorine may be evolved during the action of the battery; but 

 I find that even with the latter, the action, though powerful, 

 is one quarter less than with strong nitric acid. 



A coke battery of two cells, with eight ounces of nitric 



* The coke may be cut with a saw into any convenient shape, whilst 

 phuiibago, though softer, has the singular property of" wearing clown every 

 tooth from the instrument in a very short time. 



