Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.

inum, besides being very much cheaper. In the original Bun- sen's battery, there was arranged a cylinder of baked carbon, open at its bottom and placed in the glass jar, within which was a porous diaphragm of pipe clay, which contained the zinc and dilute sulphuric acid, while dilute nitric acid filled the jar about this large body of carbon. But this has lately been improved, so as to dispense with the porous diaphragm altogether. The author has seen some of these improved carbon cups, with closed bottoms, so prepared by T. Hall, for the professor of chemistry at Harvard. Some five or six cups produced a heating, chemical, and decomposing power, equal to fifty cells of best Cruikshank's. In this case the carbon cup is fitted with dry, powdered carbon, and moist- ened with nitric acid. For cauterizing, this is the battery, as it possesses the most tremendous quantity power; but it does not last very long in action, nor is it required to act long for such purposes. (See page 659.) Smee's battery is the most clean, and one of the most permanent and economical arrangements we know of. This is ar- ranged in a quart or half-gallon glass jar, by mostly filling it with water acidulated by one tenth or one fifteenth part of sul- phuric acid. Into this are plunged two flat, square plates of zinc, say four by six inches, and one half inch thick, and coated with mercury, which are suspended from the top. Between these there is arranged the thin plate of platinum or platinized silver. This apparatus can remain in working order for a month, but if much used should be overhauled once a week; that is, the zinc plate should be new coated with quicksilver, and if that is well at- tended to, for dentists and other office use it will wear a year or more. DanielVs battery is now so improved that it is the most perma- Fig. u. Smee's CoDstant Battery.