BATTERIES, ETC.] UNDULATORY FORCES. ELECTRO-METALLURGY. 



tho circuit. The most usual means adopted of increasing 

 tlio Intensity of the current, is to add to the number of 

 tlie batteries; and for increasing the quantity, to im- 

 inei-se all the battery plates deeper in their liquids.* 

 Sometimes, to increase the power, tho temperature of 

 the liquid may be raised, or the article placed nearer 

 the dissolving metal ; and when a smaller quantity of 

 current is required than the ordinary batteries can con- 

 veniently supply, a piece of sheet metal may be hung in 

 the depositiug solution with the receiving article, to 

 receive a portion of the deposit, and thus transfer some 

 of the power from the article to itself 



188. Intensity and Quantity of the Current. The in- 

 tensity of the current obtained from a scries of batteries, 

 depends upon the number of alternations of the metals ; 

 whilst its quantity depends upon the amount of immersed 

 surface in each alternation ; and it makes no difference 

 whether that amount of surface is in one battery plate 

 or in many, or iu one or many containing vessels. A 

 series of similar batteries may be so connected together 

 by wires or other conductors, as to give either an inten- 

 sity or a quantity of current, provided they have screws 

 or other conveniences for attaching tho wires to the 

 plates. For instance 1st, if we have four pairs of 

 plates, in four separate cells, and connect them alter- 

 nately, thus (Fig. 87), zinc, silver zinc, silver zinc, 

 rig. sr. 



silver zinc, silver, with wires from the terminal plates, 

 we obtain a current possessing the intensity of four 

 pairs, and the quantity of one ; but if, 2nd, they are 

 connected, all the zincs by one wire, and all tho silvers 

 by another wire (Fig. 88), with one portion of each wire 



Fig. 88. 



left convenient for making connections, we obtain a 

 current possessing the quantity of four pairs, and the 

 intensity of one ; and, 3rd, if they are arranged in two 

 series or rows, two pairs in each, each series being con- 

 Fig. 89. 



nocteil intensity-fashion, Ihe end silvers of each row 

 facing one way and connected by one wire, and tho 



Sec ante, p. 187. 



terminal zincs facing the opposite way and connected by 

 another wire, and these wires left free for connection 

 with the vat (Fig. 89), we obtain a current possessing 

 the intensity of two pairs and the quantity of two. By 

 contrivances of connection like these, any number of 

 batteries, provided they are similar in kind, charged 

 alike, and have suitable connecting screws attached, 

 may be connected together so as to give any desired 

 quantity or intensity of current within the limits of their 

 power: thus, a battery of one hundred pairs may bo 

 arranged to yield a current having tho intensity of one 

 hundred pairs, and the quantity of one ; the quantity of 

 one hundred, and the intensity of one ; the intensity of 

 fifty, and the quantity of fifty; or any intermediate 

 degree of each. 



189. Regulating the Quantity of Deposited Metal. The 

 quantity of metal dissolved and deposited iu the vat, is 

 in direct proportion to the quantity of zinc dissolved 

 and acid consumed in each alternation of the battery. 

 With a perfect depositing liquid, good battery arrange- 

 ments, and pure materials, for every equivalent of zinc 

 dissolved in each alternation of the battery, an equiva- 

 lent of metal is dissolved on one side, and an equivalent 

 deposited on the other, in the depositing vessel. For 

 instance for every equivalent (32 - G parts) of zinc so 

 dissolved, and 49 parts, or one equivalent, of oil of 

 vitriol consumed in tho battery, an equivalent (31 '7 



parts) of copper is deposited in the sulphate of 

 copper solution, or an equivalent (108 parts) of 

 silver in the cyanide silver plating liquid, and 

 similar quantities of copper or silver dissolved 

 at the anode. But in practical working, the mate- 

 rials are rarely or ever pure, or tho arrange- 

 ments perfect ; the zinc nearly always contains a 

 small proportion of other substances ; the mer- 

 cury contains tin or lead ; and tho sulphuric 

 acid contains a little nitric acid. The acid liquid 

 of the battery is often too strong: much acid 

 liquid is frequently wasted, being thrown away before 

 it is completely exhausted : tho zinc plates have not 

 been kept well amalgamated, or tho silver well plati- 

 nised, or the plates have been suffered to remain too 

 long in the liquid when not in use. The metal of 

 the anode is frequently impure also ; occasionally some 

 of tho deposit is allowed to redissolve, in con- 

 sequence of the battery power becoming low, and 

 from not stirring tho solution ; in some solutions, 

 a part of the battery strength is expended in 

 evolving gas at the cathode ; and, finally, the 

 repeated operation of "scratching" removes some 

 of the deposit. Allowing for all these and other 

 unavoidable sources of loss in practical working, 

 about one pound only of copper can be deposited 

 in the ordinary sulphate solution, by the con- 

 sumption of from one-and-a-quarter to one-and- 

 a-half pounds of zinc, and an equivalent quantity 

 of acid, in each alternation of the battery. To increase 

 the quantity of metal deposited in a given period of time, 

 tho battery plates should be sunk deeper in their liquids. 



190. Regulation of the Quality of the Deposit. The 

 quality of the deposited metal, i.e., its degree of cohe- 

 sion, hardness, flexibility, Arc., depends upon the inten- 

 sity of tho current. As a general rule, the greater the 

 intensity and the smaller the quantity of the current, 

 tho harder and. brighter is the deposited metal ; and the 

 greater the quantity and the smaller tho intensity, tho 

 less coherent and the softer it is. To obtain a very hard, 

 bright, and crystalline deposit, wo should use a current 

 of small quantity and liigh intensity; and to obtain a 

 soft black powder deposit, we should employ largo quan- 

 tity and low intensity; the combination of moderate 

 quantity and moderate intensity, produces a coherent 

 regulino deposit, possessing all the ordinary character- 

 istics of tho particular metal. These results can only 

 bo obtained with a good depositing liquid, and with 

 metals, such as copper, silver, gold, &c., which are 

 known to exist in a tough reguline state; and not with 

 those such as bismuth or antimony, crystalline metals 

 which do not exist in that state. 



