176 ANNUAL OF SCIENTIFIC DISCOVERY. 



the voltaic pile of zinc and copper plates ; as many or as few as 

 are desired can be used without delay in arrangement. A very 

 strong current, either as to quantity or tension, is not required. 

 A small quantity is sufficient to excite the nerves of the blood- 

 vessels ; and there should be just tension enough to insure that 

 the current pass through the part to be acted on, and not merely 

 round by the skin. It is believed that this is a medical agent of 

 considerable energy, and capable of yielding results of such im- 

 portance as to warrant its frequent use. — British Medical Journal. 



NEW FORMS OF GALVANIC BATTERIES. 



At a meeting of the Chemical Society, in February, 1868, Dr. 

 De La Rue described a small voltaic battery of 10 cells, constructed 

 by Dr. H. Miiller and himself, on a new principle. The negative 

 element was chloride of silver fused around a central silver wire, 

 which served as a conductor ; this was bent over and connected 

 by means of a small caoutchouc band to a rod of zinc, which 

 need not be amalgamated. The exciting liquid was salt water, 

 which in course of time became charged with chloride of zinc, and 

 required to be renewed only when metallic zinc began to be de- 

 posited on the negative plate. Ten of these little couples, 3 

 inches or less in height, were mounted on a wooden frame sup- 

 ported and sliding upon glass uprights, so that the battery was 

 very easily put in action. Its tension was so great that a cul)ic 

 inch of the mixed gases was given off from water in about 20 

 minutes. 



Constant Battery. — Boettzer has constructed a galvanic battery 

 of such constancy that it retains its activity for several years. It is 

 admirably adapted to the working of electric clocks, ringing elec- 

 tric bells, and the requirements of electro-metallurgy. Each cell 

 consists of a cylinder of thick plate zinc, enclosed in a glass jar. 

 In the centre of the cylinder is placed a bar of compact coke, and 

 the intervening space is packed with a powder composed of a 

 mixture of equal volumes of pounded sulphate of magnesia and 

 common salt, moistened with a saturated solution of these two 

 substances. The salt mixture is moistened from time to time. — 

 Artisan. 



New Portable Battery. — Anew form of carbon Smee battery, 

 adapted for transportation, and for use where an escape of acid 

 would be very objectionable, is described, with a figure, in the 

 '• Journal of the Franklin Institute," for February, 1868. A short 

 test-tube, or like vessel, contains the dilute sulphuric acid or acid 

 sulphate of mercury, which is employed as an exciting fluid, and 

 is closed at top by a zinc cover, having a piece of soft rubber 

 beneath it to secure a tight joint, and held in place by an elastic 

 band attached to hooks or lugs, passing under a block in which 

 the tube or vessel is set. The elements, zinc and carbon, are sus- 

 pended from the cover, the carbon being insulated by a rubbcn- 

 washer. The connections between successive cells are made by 

 spiral springs of l)rass wire, which are thrust over conical points, 



