9)2 



UNDDLATORY FORCES. ELECTRO-METALLURGY. (LAWB or DKPOBITIOIC. 



that IX.W.T frmn it* contact with the metal in 

 tin- nthor liijuiil; 6th, that, as a general rule, b<wo 

 metals have a greater power of causing deposition by 

 thin method than the noble one* ; 6th, that the noble 

 metals are more readily and more often deposited than 

 th.- lue ones; and 7th, that we may produce thick and 



i. -posits by this method. 



11. Dtpon&ng Arrangement No. i. Deposition by Two 

 MttaU and Turn Liquid*. The following instances 

 belong to the class of deposition produced 

 by the immersion of two metals, A and B 

 (Fig. C!>), in two liquids, D and E, the 

 ' metals being in mutual contact, or con- 

 B nected together by a wire C, and the 

 liquids separated by a porous parti- 

 ti.i F. 



Zinc Depositing Antimony. If a piece 

 of antimony A be immersed in a solution 



of chloride of antimony D, and a piece of 



zinc B be immersed in dilute sulphuric acid E, and the 

 twn metals are connected together by a wire or wires C, 

 a free deposit of antimony upon the metal A will take 

 place in twelve hours. 



Y'm Depositing Zinc. With tin in hydrochloric acid, 

 and zinc in a neutral solution of sulphate of zinc, a de- 

 posit of zinc is obtained in the metallic solution. 



Iron Depositing Antimony. With iron in dilute hy- 

 drochloric acid, and antimony in chloride of antimony, a 

 copious deposit of antimony takes place in twelve hours. 

 Copper Depositing Zinc. With zinc in dilute sulphu- 

 ric acid, and zinc in a solution of sulphate of zinc, a 



: of zinc occurs. 



/i lie Depositing Copper. With zinc in dilute sulphu- 

 ric acid, and brass in a solution of sulphate of copper, 

 copper is deposited. 



Bismuth and Chloride of Antimony. With bismuth in 

 dilute hydrochloric acid, and antimony in chloride of 

 antimony, no deposit of the latter takes place in twenty- 

 four hours. 



Iron and Chloride of Tin. With iron in dilute hy- 

 drochloric acid, and tin in a solution of chloride of tin, 

 no deposit of tin took place in eighteen hours. 



Copper and Chloride of Antimony. With copper in 

 dilute hydrochloric acid, and antimony in chloride of 

 antimony, or tin in chloride of tin, no deposit of anti- 

 mony or tin took place in twenty hours. 



12. Obrervations upon Class of Instance* No. 4. 1st, it 

 appears that negative as well as positive instances occur 

 in this arrangement in common with the others ; 2nd, 

 that by using suitable metals and liquids, deposition 

 may be effected more rapidly by this method than by 

 the preceding ones ; 3rd, that the metal which receives 

 the deposit derives its power from its contact with 

 the other metal ; 4th, that base metals in strong acids 

 have the greatest power of causing a deposit upon the 

 other metals, and noble metals the least ; 6th, that the 

 noble metals are more readily deposited than the base 

 ones ; and Oth, that thick and coherent deposit may be 

 obtained. 



In all the above instances, instead of using one vesse 

 divided into two part* by a porous diaphragm, it will be 

 found convenient to put one of the liquids in an unglaax 

 earthenware porous cell, and immerse the cell in the 

 other liquid. (See vessel A, Fig. 71). In this case, eitho; 

 liquid may be in the outer vessel This last arrange- 

 ment (No. 4) is usually termed the "single cell" process. 



13. Depositing Arrange- 

 ment No. 5. Deposition 6j 

 Separate Liquid. The nex 

 class of instances are thos 

 in which either of the fore- 

 going arrangements, excep 

 the first, may be connect** 

 by wires with two pieces o 

 similar metal immersed in a 

 separate liquid. For in- 

 stance : 



1st With Two Metals and Jne Liquid (Fig. 70). If we 

 take a vessel A, containing either dilute sulphuric acid 



or a solution of sulphate of copper, and immerse in it a 

 piece of zinc B and copper C, with copper wires D and E 

 attached to them, anil i-itluT immerse the free ends of 

 those wires in a separate solution <>f sulphate of copper 

 F, or connect them with two pieces of copper immersed 

 in that liquid, the piece of copper E in liquid F will 

 dissolve, whilst the opposite piece D, connected with the 

 zinc, will receive a deposit of copper. 



2nd. With One Metal and Two Liquids. If we take a 



essel A (Fig. 71) containing a porous cell B, with a 



eutral solution of sulphate Fig. 71. 



f zinc C in the outer 



essel, and dilute sulphuric 

 acid D in the inner, and 



inmerse two pieces of zinc 



5 and F, with copper wires 

 Q and H attached, into D 



nd C respectively, and 



ramerse the ends of those 

 wires in a separate solution 

 )f sulphate of copper I, 



he end of the wire H will 



dissolve, whilst that of G will receive a deposit 

 metallic copper. 



3rd. With Two Metals and Two Liquids (" single cell" 

 arrangement, Fig. 71). If we substitute a piece of 

 copper for the piece of zinc F in the last-mentioned 

 instance, and a solution of sulphate of copper for that of 

 sulphate of zinc, similar effects will take place at the 

 ends of the wires in the liquid I, except that the action 

 will be much more rapid ; but if in either of these three 

 instances we use a solution of sulphate of zinc freely 

 acidulated with sulphuric acid, instead of the solution of 

 sulphate of copper I, and platina wires in place of the 

 copper ones to be immersed, neither of the pieces of 



jlatina will dissolve or receive a metallic deposit. 



14. Remarks upon Class of Instances No. 6. In this 

 class of instances, the method or arrangement differs 

 from the three preceding ones, simply by the wires which 

 connect the two pieces of metal being cut in two, and their 

 Free ends either immersed in a separate liquid, or con- 

 nected with two pieces of metal dipping into that liquid. 

 It is not necessary to have the depositing-vessel perfectly 

 separated ; it may even be attached to the same piece of 

 apparatus, provided the liquid in it is perfectly sepa- 

 rated from the other liquids and metals. The pieces of 

 metal in the separate liquid possess no power of depo- 

 sition of themselves in that liquid, even if they were 

 connected together, but derive their power of dissolving 

 and receiving a deposit wholly from the other metals and 

 liquids by means of the wires. 



15. Depositing Arrangement No. 6. Deposition by 

 Magnet and Coil (Fig. 72). We may produce deposition 

 in the separate liquid by connecting the twc pieces of 

 immersed metal with any other source of depositing 

 power for instance, if a long copper wire A, covered 

 with silk or cotton, be coiled upon a large bar of pure 

 soft iron B, and its ends C and D are immersed m a 

 solution of sulphate of copper E, and the poles of a 

 powerful horse-shoe magnet F are brought in contact 

 very many times with the end of the bar, and every 

 time before removing the magnet from the bar one 



Flf. 7J. 



of the ends of the wire be taken out of the liquid, 

 and replaced before returning the magnet, one end of 

 the copper will slightly dissolve, and the other receive 

 a thin copper deposit ; but if each of the ends bo allowed 

 to remain constantly in the liquid, no such effects will 

 occur. 



16. Compound Depositing Arrangement No. 7. Any of 

 the foregoing combinations of liquids and metals (except 

 the first), or the magnetic arrangement, with or without 



