The Dental record . is chlorideof ammonium. Another form, patented June 5th, 1866, and reissued February 17th,1874, consists of a plate of copper with wire attached, which iscovered in the jar with powdered carbonate of copper ; over this isplaced a stratum of sand in which is imbedded the zinc with a wireattached. The whole is then saturated with a solution of chloro-hydrate of ammonium. The more modem Leclanche battery, which is now largely usedfor electric bells, telephones, and in local telegraph stations,is not very constant, but it rapidly recovers its primitive powerwhen allowed to rest
The Dental record . is chlorideof ammonium. Another form, patented June 5th, 1866, and reissued February 17th,1874, consists of a plate of copper with wire attached, which iscovered in the jar with powdered carbonate of copper ; over this isplaced a stratum of sand in which is imbedded the zinc with a wireattached. The whole is then saturated with a solution of chloro-hydrate of ammonium. The more modem Leclanche battery, which is now largely usedfor electric bells, telephones, and in local telegraph stations,is not very constant, but it rapidly recovers its primitive powerwhen allowed to rest a short time, by the binoxide of manganesegradually destroying the polarisation. It is clean, convenient,portable, and gives oflf no unpleasant odours; it will run for monthsor even years without renewing. I have had a battery of these cellsin use for a period of over three years without any trouble savethe addition of a little water to the cells to replace that lost byevaporation. •22 IHE DENTAL RECORD. porous c. There are two kinds of this battery, one with and one without the:ell; the latter is now mostly used. The first, Fig. 14, consistsof a rod of carbon placed in a porous pot,which is then packed with a mixture of granulesof carbon and binoxide of manganese; this iscovered over with a layer of pitch. Thepositive plate is a rod of zinc to which is fixeda copper wire. The exciting fluid is a strongsolution of sal-ammoniac. In the chemicalaction which occurs in this cell the zinc dis-solves, forming a double chloride of zinc andammonia, while ammonia gas and hydrogenare liberated at the carbon pole ; the binoxideFi,,_ ,^. of manganese slowly yields up oxygen and destroys the hydrogen bubbles. The internal resistance of this battery varies of course with thesize, but is stated to be from two to three times that of an Ohm ;and its E. M. F. about one third greater than that ofa Daniells cell, or 1-42. In the latter form. Fig. 15,the necessity of a porous jar is avoided by e
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Keywords: ., bookcentury1800, bookdecade1880, bookpublisherlondon, bookyear188
