788 EEPOET— 1888. 



that we hare reached the proper accumulator. Nor have we yet acquired the best 

 motor and mode of gearing ; but very active experiments are being carried out in 

 various countries, and nothing can prevent their ultimate success. 



The propertjf, which the electric current possesses, of doing work upon the 

 chemical constitution of bodies so as to break up certain liquid compounds into 

 their constituent parts, and marshal these disunited molecules in regular order 

 according to a definite law upon the surfaces of metals in contact with the liquid 

 where the current enters and exists, has led to immense industries in electro- 

 metallurgy and electro-plating. The extent of this industry may be gathered from 

 the fact that there are 172 electro-platers in Sheffield and 99 in Birmingham. The 

 term electro-metallurgy was originally applied to the electro-deposition of a thin 

 layer of one metal on another ; but this is now known as electro-plating. 



In 1839 Jacobi in St. Petersburg and Spencer in Liverpool laid tlie foundations 

 of all we Imow of these interesting arts. Copper was deposited by them so as to 

 obtain exact reproductions of coins, medals, and engraved plates. The first patents 

 in this country and in France were taken out by Messrs. Elkington of Birmingham, 

 who still occupy the foremost position in the country. 



The fine metals, gold and silver, are deposited in thin layers on coarser 

 metals, such as german silver, in immense quantities. Christofle of Paris deposits 

 annually six tons of silver upon articles of use and of art, and if the surfaces 

 so electro-plated were spread out continuously they would cover 140 acres. 



The whole of the copper plates used in Southampton for the production of our 

 splendid Ordnance Survey maps are deposited by current on matrices taken from 

 the original engraved plates, which are thus never injured or worn, are always 

 teady for addition or correction, while the copies may be multiplied at pleasure and 

 renewed at will. 



Nickel-plating, by which the readily oxidisable metals like iron are coated with 

 a thin layer of the more durable material nickel, is becoming a great industry ; the 

 trappings of harness, the exposed parts of machinery, the fittings of cycles and 

 carnages, and innumerable articles of daily use are being rendered not only more 

 durable but more beautiful. 



The electro-deposition of iron, as devised by Jacobi and Klein, in the hands of 

 Professor Roberts- Austen, F.R.S., is giving very interesting results. The designs for 

 the coins which were struck at our Mint on the occasion of the Jubilee of the 

 Queen were modelled in plaster, reproduced in intaglio by the electro-deposition 

 of copper, and on these copper moulds hard excellent iron in layers of nearly y^^th 

 of an inch was deposited. fjft&.t. 



The exact processes of measurement, which have led to such vast improvement 

 in our telegraphic systems, have scarcely yet penetrated into this field of electrical 

 industry, and little is known at present of the exact relations of current and 

 electromotive force with respect to surfaces of contact, rate of deposit, and resistance 

 of liquids. Captain Sankey, R.E., of the Ordnance Survey Department, has done 

 some useful work in this direction. 



The extraction of metals from their ores by deposition has received wide appli- 

 cation inthe case of copper. In 1871 Elkington proposed to precipitate copper 

 electrolytically from the fused sulphide of copper and iron known to the copper 

 smelter as'regulus.' Thin copper plates were arranged to receive the deposited 

 copper, while the foreign metals, iocluding gold and silver, fell to the bottom of the 

 solution, the process being specially applicable, it was supposed, to regulus contain- 

 ing small quantities of the precious metals. 



The electrical purification of copper from impure 'blister copper' or 'blade 

 copper ' has also made great progress, and special dynamos are now made which 

 will, with an expenditure of 100 horse-power, precipitate 18 tons of copper per 

 week. The impure metal is made to form the anode in a bath of sulphate of 

 copper, the metal being deposited in the pure form on a thin copper cathode. 



It was not very long ago considered very economical to absorb '85 horse-power 

 in depositing one pound of copper per hour, but now the same work can be done 

 with -3 horse-power. Mr. Parker of Wolverhampton has done good work in this 

 direction, and his dynamos in Messrs. Bolton's works have revolutionised this 

 process of purification. 



