UNDULATORY FORCES ELECTRO-METALLURGY. 



199 



of clean iron in a solution of sulphate of copper, it will 

 become coated with copper ; but if we immerse a piece of 

 silver in that liquid, it will not become so coated. 



2nd. Two Metals in One Liquid. By the immersion of 

 two metals in one liquid (Fig. 60), the two metals being 

 Fig. 60. Fig. 61. in contact with each other : 



for instance, if we connect 



A r r "/ a piece of silver A and a 



" K " = ~^ J piece of iron B togethc 



and immerse them in a 

 solution of sulphate of 

 copper C, the silver will 

 |C ii 1 1 become coated with copper 



as well as the iron ; but if 

 a piece of silver in contact 

 with a piece of gold or platina be immersed in the 

 same liquid, it will not become coated. We have already 

 seen, that silver immersed alone in such a liquid, will not 

 receive a deposit of copper. 



3rd. One Metal in Two Liquids. By the immersion of 

 one metal (i.e., one kind of metal) in two liquids D and 

 Fig. 62. E (Figs. 61 and 62), the liquids being 



prevented from mixing with each other 

 either by a porous partition F (Fig. 61) 

 of bladder, thin wood, unglazed earth- 

 enware, or other porous material which 

 will allow the two liquids to touch 

 each other through its pores ; the 

 piece of metal being either bent so as 

 to dip into each liquid, or cut into two 

 portions, and its two ends united by a 

 wire C, the end or piece to receive the 

 deposit being immersed in one liquid, 

 and the other piece in the other liquid 

 (Fig. 61) ; or the two liquids being 

 put in a deep narrow vessel, the 

 heavier one being poured in first, and 

 the lighter one poured carefully above 

 it so as not to mix them together, and 

 the piece of metal being in the form of 

 a rod or wire placed vertically in the 

 ' two liquids (Fig. 62) ; for instance, if 

 the lower li'|ui<l consist of a solution of sulphate of 

 copper, and the other of dilute sulphuric acid, and a 

 piece of copper be immersed in both liquids, that part of 

 it which is in the sulphate solution will become coated 

 with copper, whilst that in the acid liquid will be partly 

 dissolved ; but if, instead of copper, we use a piece of 

 platina, it will neither be dissolved nor receive a metallic 

 deposit. 



4th. Two Metals in Two Liquids. By the immersion of 

 Fig. 63. tt.ro metals A and B (Fig. 63) ii 



liquids, D and E, the two being, as in the 

 last arrangement, either separated by a 

 porous diaphragm F, or poured one above 

 1 the other, the two metals being immersed 

 one in each liquid, and connected together 

 by a wire C : for instance, if one liquid 

 be dilute sulphuric acid, and the other a 

 solution of sulphate of copper, and a 

 piece of copper be immersed in the dilute 

 acid, and a piece of silver in the metallic solution, the 

 two metals being thus in mutual contact, the piece of 

 copper will dissolve, and the silver receive a deposit of 



Zper; but if we immerse a piece of platina in the 

 te acid with the silver in the sulphate solution, the 

 platina will not dissolve, nor the silver receive a metallic 

 Fig. 64. deposit. 



5th. Separate Depositing 

 Liquid with all the others. 

 By connecting any one of the 

 foregoing arrangements by 

 means of wires with two 

 separate pieces of metal of 

 a similar kind immersed in 

 a separate and suitable 

 liquid (Fig. 64): for in- 

 itance, if we take the arrangement of two metals in 

 one liquid, such as iron B and copper C, in a solution 



of sulphate of copper A; or zinc B and silver C in 

 dilute sulphuric acid A, and connect them by two 

 separate wires, D and E, with two pieces of copper, D 

 and E, immersed in a solution of sulphate of copper 

 F contained in a separate vessel, the piece of copper 

 E connected with the silver will dissolve, whilst the 

 other piece D which is connected with the zinc will 

 receive a deposit of copper; but if we substitute a 

 solution of sulphate of zinc, freely acidulated with 

 sulphuric acid, for the solution of sulphate of copper 

 F, and two pieces of platiua for the pieces of copper, 

 the one piece of platina will not dissolve, nor the other 

 receive a metallic deposit. 



6th. Separate Depositing Liquid with any other Source of 

 Power. By connecting the pieces of metal in the 

 separate depositing liquid with any other source of de- 

 positing power, such as a magneto-electric machine, cell, 

 or battery. 



2. In these arrangements, it will be observed that we 

 have 1st, deposition by one metal and one liquid ; 2nd, 

 by two metals and one liquid ; 3rd, by one metal and 

 two liquids; 4th, by two metals and two liquids; 6th, 

 by a separate depositing liquid and metals connected 

 with either of these ; and 6th, by a separate depositing 

 liquid and metals connected with any other source of 

 depositing power. These six classes, and their com- 

 binations, are capable of including all the known cases of 

 electro-deposition. 



3. Under the head of each of these classes will be 

 mentioned a number of experiments with various nietals 

 and liquids ; and it would be advisable for the student to 

 try a few, as he proceeds, both of deposition and non- 

 deposition of each class, in order to fix the facts more 

 firmly in his memory, and give him a fuller compre- 

 hension of the principles. 



4. Depositing Arrangement No. 1. Deposition by 

 one metal and one liquid (Fig. 65) takes Fig. 65. 

 place in the following instances : 



Hydrochlorate of Terchloride of Anti- 

 mony. In a solution of hydrochlorate of 

 terchloride of antimony (the ordinary 

 chloride of antimony, as prepared for phar- 

 maceutical purposes), bismuth, zinc, tin, 

 lead, brass, and German silver, become 

 coated with antimony; whilst antimony, 

 iron, nickel, copper, silver, gold, and platina do not 

 become coated. 



Chloride of Bismuth. In a solution of acid hydro- 

 chlorate of bismuth oxide (chloride of bismuth), zinc, 

 tin, lead, and iron, deposit the bismuth upon themselves ; 

 whilst antimony, bismuth, copper, brass, German silver, 

 gold, and platina do not. 



Sulphate, Chioride, Nitrate, or Acetate of Zinc. In a 

 solution of either sulphate, chloride, nitrate, or acetate 

 of zinc, neither antimony, bismuth, zinc, tin, lead, iron, 

 nickel, copper, brass, German silver, silver, gold, or 

 platina become coated with zinc. 



Protochloride of Tin. In a solution of protochloride 

 of tin, zinc and lead become tinned ; whilst antimony, 

 bismuth, tin, iron, nickel, copper, brass, German silver, 

 silver, gold, and platina receive no deposit. 



Hyponitrate, Nitrate, or Acetate of Lead. In a solution 

 of hyponitrate, nitrate, or acetate of lead, zinc receives 

 a coating of lead ; whilst antimony, bismuth, tin, lead, 

 iron, nickel, copper, brass, German silver, silver, gold, 

 and platina receive no deposit. 



Ferrous Sulphate. "Zinc," as Fischer says, "im- 

 mersed ii. a perfectly neutral solution of ferrous 

 sulphate (protosulphate of iron) contained in a stoppered 

 bottle, throws down metallic iron, which is deposited 

 partly on the zinc;" but in this solution neither an- 

 timony, bismuth, tin, lead, iron, nickel, copper, brass, 

 German silver, silver, gold, or platina receive any 

 metallic deposit. 



Sulphate of Copper. In a solution of sulphate of 

 copper, zinc, tin, lead, and iron become coated with 

 copper ; whilst antimony, bismuth, nickel, copper, silver, 

 gold, and platina do not 



Chloride of Copper. In a solution of chloride of 



