GALVANIC

Several forms of this apparatus have already been described {see Voltaic Electricity); many others have lately been invented, two of which, namely, Smee's Battery, and Grove's Battery, deserve particular notice. In Smee's battery, of which a detailed description will be found in his Elements of Electro-metallurgy, the positive or generating plates are composed of amalgamated zinc, and the negative plates of platinised silver, which, on account of its rough surface, favours the escape of the hydrogen gas.evolved upon it, the adhesion of which to platinum or silver in their ordinary state is a serious impediment to the action of the battery. One form of Smee's battery " consists of a piece of silver S, on the top of which is fixed a beam of wood w to prevent contact with the silver. A binding screw is soldered on to the silver to connect it to any required object. A strip of zinc Z, varying, at the fancy of the operator, from one half to the entire width of the silver, is placed on each side of the wood, and both are held in their place by a binding-screw b, sufficiently wide to embrace the zincs and wood. These batteries vary from the size of a tumbler to a ten or twelve gallon ve el." A single cell of this battery is represented in the annexed cut. A i« an earthenware or gla ve el containing dilute sulphuric acid (composed of 1 part of oil of vitriol to 6 or 7 of water), to is a bar of wood to which the 13-')3 BIOLOGY. platinum, or platinised silver plate is attached. Z Z are two plates of amalgamated zinc, connected and secured to the bar by a binding screw; and a separate binding screw is soldered to the platinised plate; these are for the convenience of making connections by wires. When a series of these cells are required they are connected together in the usual way. Grove's battery, called also the nitric acid battery, is an extremely valuable instrument both to the lecturer and experimentalist; it combines great power both of quantity and intensity, it is free from the inconveniences of local action, and, therefore, so far, & constant battery; it occupies little space, and is upon the whole more economical than any other form of battery po e ing the same advantages. The sections of two cells of this battery are represented in the annexed cut. The outer ve el V is a flat cell of glazed porcelain, containing within it another similarly shaped, but smaller and thinner cell C, oi porous earthenware. A flat plate of amalgamated zinc Z is bent so as to receive the porous cell; a plate of thick platinum foil P being contained within the latter cell, and long enough to extend to the projecting end of the zinc plate of the next cell, perfect contact being there preserved by the cleft piece of wood W. The inner porous cell is charged with strong nitric acid; the outer porcelain cell is filled with a mixture of I part of oil of vitriol and 6 of water. The zinc being amalgamated, there is in this apparatus, as in Daniell's, and Smee's, no chemical action till the electrical current pa es, and then the evolved hydrogen is suppre ed by the nitric acid, which it converts, by deoxydizement, into nitrous acid. Twenty of these cells form a very powerful combination. Many years ago Mr. Cooper proposed to substitute coke for platinum in these batteries, and a similar plan has been more recently adopted by Bunsen, but so much inconvenience has attended the use of this material that it has not been generally adopted. BE BE A RINE. a bitter basic principle contained in the bebearu plant or Greenheart of British Guiana. BE IS TINGS, or Colostrum. The first milk yielded by the cow immediately upon the birth of the calf. [s. 1370]