LIST OP PATENTS.] UNDULATORY FORCES. ELECTRO-METALLURGY. 230 



the resulting solution by adding to it a solution of pro- 

 tosulphate of iron ; but this appears superfluous : and I 

 am assured, by evaporation of given volumes of the same 

 solution of gold, the evaporation and calcination of the 

 sal-ammoniac, and other operations, that we have col- 

 lected in a sufficiently exact manner all the gold of 

 these solutions. 



249. "The same process is applicable to the solution 

 of silver ; and independently of the oxide of iron (of the 

 ferro-cyanide of potassium), we obtain chloride of silver, 

 which is soluble in aqueous ammonia." 



250. To further assist the reader in remembering the 

 terms applied to the different parts of the electric circuit, 

 and in understanding the action of electricity upon 

 liquids, we repeat those terms, aiid append a diagram of 

 the anode, cathode, <tc. 



S (Fig. 91) is a wire proceeding from the silver plate 

 or positive plate of a battery ; Z is another wire from the 

 zinc plate or negative plate ; the two wires are attached 

 to two pieces of metal immersed in a depositing liquid. 

 By the direction of the arrows, it will bo perceived that 

 the positive electricity circulates in one direction through 

 the circuit, and the negative electricity in he opposite 

 direction. 



The immersed pieces of metal are termed " electrodes," 

 meaning ways by which the electricity enters and leaves 



Fig. 91, 



the liquid ; the piece A is called the " anode," and is that 

 by which the positive electricity enters the liquid ; and 

 C in the " cathode," or that by which the positive elec- 

 tricity leaves the liquid. In the ordinary depositing vat, 

 the anode is that piece of metal which dissolves and sup- 

 plies the solution ; whilst the article or articles which are 

 receiving a metallic coating or deposit, constitute the 

 cathode. The liquid is termed an "electrolyte;" and 

 whilst the electric current is passing through, it is said to 

 be undergoing "electrolysis," to be "electrolysed," or 

 suffering "electro-chemical decomposition." The ele- 

 ments of the liquid are termed "ions ;" those of them 

 which combine with, or are set free at the "anode," are 

 called " anions ;" and those which combine with, or are 

 set free at the "cathode," are termed "cathions :" for 

 instance 1st, in the electrolysis of a solution of sulphate 

 of copper with copper electrodes, sulphuric acid is viewed 

 as an anion, because it is the product which combines 

 with the anode, and copper the cathion, because it is the 

 clement set free at the cathode ; and, 2nd, in the electro- 

 lysis of the ordinary cyanide silver-plating liquid, cyano- 

 gen is the anion, and silver the cathion. 



'-'."> 1. Lilt of Patent* upon Electro-Deposition. The 

 following is a chronological list of some important patents 

 which have been taken out for subjects connected with 

 tlcctro-deposition. 



Klkinytcn'i Patent. Jnno 24th, 1830: gilding copper, 

 brass, and other metals ; G. R. Elkington. 



'/ton's Patent February 17th, 1837: gilding 

 metals, and coating with platinum apparatus described : 

 II. Klkington. 



> /ton's Patent. December 4th, 1837: gilding 

 and nilvering certain metals apparatus described; H. 

 Klkington. 



it'.n nn,l Varratft Patent. July 24th, 1838: 

 coating and colouring certain metals: G. K. Elkington 

 and O. W. Barratt. 



Elkington's Patent. March 25th, 1840 : coating or 

 plating certain metals ; G. R. Elkiiigton and H. Elking- 

 ton. 



Parks' Patent. March 20th, 1841 : production of 

 works of art by electro-deposition ; Alexander Parkes. 



Barratt' s Patent. September 8th, 1841 : deposition of 

 metals ; O. W. Barratt. 



Fox Talbot's Patent. December 9th, 1841: coating 

 and colouring metals with other motals; H. II. Fox 

 Talbot. 



Zeeson's Patent. June 1st, 1842 : electro-deposition 

 with apparatus ; H. B. Zeeson. 



Tuck's Patent. June 4th, 1842: coating metals with 

 silver by electro-deposition ; E. Tuck. 



Woolrich' s Patent. August 1st, 1842: coating metals 

 and alloys with metal ; J. S. Woolrich. 



Sturges' Patent. August 10th, 1842: making plated 

 articles ; R. F. Sturges. 



Fox Talbot's Patent. November 25th, 18-12 : coating 

 metals with other motals ; H. H. Fox Talbot. 



Moses Poole's Patent. May 25th, 1843 : deposition of 

 metals with apparatus ; Moses Poolo. 



JBarratt's Patent. June 15th, 1843: gilding and plating 

 metals; O. W. Barratt 



Schottlaendei-'s Patent. December 8th, 1843: depo- 

 sition of metal upon felted fabrics ; J. Schottlacnder. 



Parked Patent. February 21st, 184 i: de- 

 position of metals and alloys ; A. Parkes. 



Pat-keif Patent. October 24th, 1844: do- 

 positing metals and their alloys ; A. Parkes. 



Parkes' Patent. October 9th, 1845 : coat- 

 ing metals and alloys ; A. Parkes. 



Lyons and Mittward's Patent. March 23rd, 

 1847: deposition of metals; Lyons and Mill- 

 ward. 



Sahede's Patent. September 30th, 1847: 

 brassing and bronzing steel, iron, ziuc, load, 

 and tin ; Charles do la Salzude. 



Fontainemoreaii's Patent. March 14th, 

 1849 : coating metals and non-metallic sub- 

 stances ; J. Fontainemoreau. 



Russell and Woolrich' s Patent. March 

 19th, 1849 : coating iron and other metals with metals 

 and alloys ; Russell and Woolrich. 



Parkes' Patent. March 2Cth, 1849: deposition of 

 certain metals and alloys ; A. Parkes. 



Smith's Patent. June 7th, 1849 : depositing motals ; 

 S. B. Smith. 



Koselew's Patent. March 23rd, 1850 : tinning metals ; 

 A. G. Roscleur. 



Steele's Patent. August 9th, 1850: coating metals; 

 Joseph Steelo. 



Hidgway's Patent. April 20th, 1852: coating glass 

 with metal by battery process ; J. Ridgway. 



Lyons' Patent. October 7th, 1852 : coating surfaces of 

 iron ; M. Lyons. 



Morriss and Johnson's Patent. December llth, 1852: 

 deposition of brass and alloys ; Morriss and Johnson. 



Junot's Patent. December 28th, 1852 : reducing metals 

 by electricity and plating ; C. J. E. Junot. 



Power's Patent. December 29th, 1852 : silvering 

 metals and glass ; J. Power. 



Newton's Patent. July 29th, 1853 : improvements in 

 depositing metals and alloys of metals ; W. E. Newton. 

 Newton's Patent. August 5th, 1853 : coating cast-iron 

 with metals and alloys ; W. E. Newton. 



Person's Patent. April 27th, 1854 : electro-coating 

 with zinc ; C. C. Person. 



Joubert's Patent for the Acierage of Engraved Plates. 

 In the preceding pages, we have repeatedly referred to 

 the applications of electro-metallurgy in the art of en- 

 graving and printing. To them, M. Joubert has made 

 a most valuable addition, in his method of coating 

 engraved copper-plates with iron, by means of electro- 

 chemical action. As the invention is of the highest im- 

 portance, and as it has been extensively adopted by many 

 engravers, we shall not hesitate to give an extended 

 description of it, availing ourselves of the report 

 furnished in the Journal oj the Society of Arts, for 



