LAWS OP DEPOSITION.] UNDULATORY FORCES. ELECTRO-METALLURGY. 



201 



a deposit of copper ; whilst silver in contact with anti 

 mony, or platina in contact with brass, receive n< 

 deposit. 



Oxide of Copper in Ammonia. In a solution of oxid 

 of copper in ammonia, platina in contact with zinc re 

 ceives a deposit; but silver in contact with iron 

 does not. 



Nitrate of Mercury. In a solution of nitrate of mer 

 cury, silver in contact with either zinc or iron, or pla 

 tina in contact with copper, receive a metallic deposit 

 but platina in contact with silver does not. 



Nitrate of Silver. In a solution of nitrate of silver 

 gold in contact with zinc receives a deposit of silver 

 but in contact with platina it does not. 



Bichlorirle of Platina. In a solution of bichloride o 

 platina, platina in contact with zinc becomes coate< 

 with platina; but in contact with gold it receives no 

 such coating. 



8. Observations upon Class of Instances No. 2. Th 

 following general observations may be made upon th_ 

 foregoing facts : 1st, that in some instances deposition 

 does, and in others it does not, occur ; 2nd, that no 

 metal will cause another metal to be coated by this 

 method, unless it can coat itself in the same liquid by 

 simple immersion for instance, zinc cannot coat itseli 

 witli zinc in solutions of zinc, neither can it cause other 

 metals to become coated with that metal in those solu- 

 tions ; copper cannot coat itself with zinc in a solution 

 of sulphate of zinc, or with tin in a solution of chloride 

 of tin ; neither can it cause silver, gold, or any other 

 il, to become coated with zinc or tin, in those 

 ; 3rd, that one of the two metals which receive a 

 deposit by this method, derives its power of receiving 

 the deposit by virtue of its contact with the other 

 metal ; 4th, that any metal which has the power of 

 coating itsaif by simple immersion in a given liquid, 

 can, by this method, cause other metals which do not 

 coat themselves by simple immersion in that liquid to 

 become coated for instance, zinc, tin, and iron coat 

 themselves with copper by simple immersion in a solu- 

 tion of sulphate of copper ; and silver, gold, and platina 

 do not ; but if either of the former metals be connected 

 with either of the latter, and the two are immersed 

 together in that liquid, the latter metals, as well as the 

 former, will become coated with copper ; 5th, that base 

 metals, and especially zinc, have generally the power of 

 ' other metals to become coated by this method ; 

 whilst the noble metals, and especially gold and platina, 

 rarely possess this power ; 6th, that by this method, 

 metal is deposited much more frequently from solutions 

 of the noble metals, than from those of the base ones ; 

 and 7th, that thick deposits of metal may be obtained 

 by this method, provided the action is continued suffi- 

 ciently long, and the liquid properly renewed. 



Fig. 67. 9. Depositing Arrangement No. 3. 



Deposition by OM Metal and Two 

 Liquids Chloride of Antimony. The 

 following instances belong to deposi- 

 tion by the immersion of one metal 

 in two liquids, D and E (Fig. 68), 

 separated by a porous diaphragm F, 

 the metal being either in two pieces, 

 connected together by a wire or wires 

 C, or in one piece, and bent so as to 

 dip into both liquids: the diaphragm 

 rig. M. may be dispensed with, 

 as already explained 

 (1), by pouring the 

 lighter liquid carefully 

 I B above the other, and 

 placing the piece of me- 

 tal vertically, as seen in 

 Fig. 67. If two pieces of 

 antimony, A and B, 

 connected together by 

 a wire or wires C, are immersed, one in dilute nitric 

 a<:id D, and the other in a solution of chloride of anti- 

 ni'iiiy E, tin; piece in the dilute acid will dissolve, whilst 

 that in the chloride solution will receive a metallic deposit. 

 VOT.. I. 



Chloride of Bismuth. If two pieces of antimony are 

 immersed in the previous manner, one in hydrochloric 

 acid, and the other in a solution of chloride of bismuth, 

 that in the acid will dissolve, and the other receive a 

 coating of bismuth. 



Sulphate of Copper. With antimony, in dilute hydro- 

 chloric acid on one side, and in a solution of sulphate of 

 copper on the other, a deposit of copper is obtained. 



Chloride of Bismuth. With bismuth in hydrochloric 

 acid on one side, and in a solution of chloride of bismuth 

 on the other, a free deposit of bismuth is soon obtained. 

 Chloride of Zinc. If a piece of zinc be bent so as to 

 dip into dilute hydrochloric acid on one side, and into a 

 neutral solution of chloride of zinc on the other, a free 

 deposit of zinc will be found upon the end in the metallic 

 solution after a period of twelve hours. 



Solution of Acetate of Zinc. With zinc in a solution 

 of acetate of zinc on one side, and in dilute sulphuric 

 acid on the other, that in the dilute acid will dissolve, 

 whilst the other end will receive a metallic deposit. 



Inm in Chloride of Antimony. With iron in dilute 

 sulphuric acid on one side, and in a solution of chloride 

 of antimony on the other, the end in the metallic solu- 

 tion will receive a deposit of antimony, whilst that in 

 the dilute acid will dissolve. 



Iron in Sulphate of Zinc. With iron in dilute sul- 

 phuric acid on one side, and in a solution of sulphate of 

 zinc on the other, no deposit of zinc is obtained in 

 twelve hours ; similarly with iron, dilute sulphuric acid, 

 and a solution of protosulphate of iron, no deposit occurs 

 in twelve hours. 



Tin in Chloride of Tin. With tin in dilute hydrochlo- 

 ric acid on one side, and in a solution of chloride of tin 

 on the other, a deposit of tin is obtained. 



Zinc in Sulphate of Zinc. With zinc in dilute sulphu- 

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

 deposit of zinc occurs in twelve hours. 



Bismuth in Nitrate of Bismuth. With bismuth in 

 dilute nitric acid, and in a solution of acid nitrate of 

 bismuth, a thin deposit of bismuth is found in twelve 

 hours. 



Copper in Sulphate of Zic.~_With copper in dilute 

 sulphuric or dilute nitric acid on one side, and in a 

 solution of sulphate of zinc on the other, no deposit of 

 zinc occurs in twelve hours. 



Brass or Copper in Sulphate of Copper. With brass or 

 x>pper in dilute sulphuric acid on one side, and in a solu- 

 tion of sulphate of copper on the other, a deposit of 

 copper is obtained in twelve hours; similarly with 

 copper in dilute hydrochloric acid, and in a solution of 

 chloride of copper, a metallic deposit occurs. 



Silver in Plating Liquid. With silver in either dilute 

 sulphuric or dilute nitric acid on one side, and in a 

 solution of sulphate of copper on the other, no deposit of 

 copper takes place in twelve hours ; but with silver in a 

 solution of cyanide of potassium on one side, and in the 

 louble cyanide of potassium and silver on the other, a 

 ree deposit of silver takes place upon the end or piece in 

 rhe latter solution. 



Platina in Nitrate of Copper. With platina in aqua 



regia on one side, and in either a solution of nitrate of 



copper, the ordinary cyanide gilding solution, or a solu- 



ion of bichloride of platina on the other, no deposit of 



x>pper, gold, or platina occurs. 



10. Observations on Class of Instances No. 3. 1st, it 



ippears, that in this class also we obtain negative as well 



is positive instances ; 2nd, that by this arrangement, 



iniiko the previous classes, almost any metal may cause 



.he same metal to be deposited for instance, zinc may 



eposit zinc, copper deposit copper, and silver deposit 



ilver ; 3rd, that by it even a noble metal may cause tho 



eposition of a base metal, provided we have a suitable 



nin I >i nut inn of liquids for instance, if a piece of gold 



r silver be immersed in a strong solution of cyanide ot 



jotassium on one side, and in a solution of sulphate of 



-opper or chloride of antimony on the other, the end in 



be free cyanide solution will dissolve, whilst that in 



de copper or antimony solution will receive a deposit ; 



th, that the metal, or end which receives a deposit 



