ON THE APPLICATION OF SCIENCE TO ELECTRO- 
PLATE MANUFACTURES. 
PART II. 
HE success of an important enterprise has frequently de- 
pended upon an apparently trivial circumstance, and it was 
even so with the important process of silver electro-plating 
in the early period of its development. In the year 1888, 
Messrs. G. R. & H. Elking’ton were engaged, commercially, in 
coating military and other metal ornaments with gold and 
silver, by immersing them in various solutions of those metals, 
some of which were composed of ferrocyanide of potassium, 
and also carbonate of potash, with the oxides of gold and silver 
dissolved in them. 
By this process of simple immersion, although the action 
was electrical, the articles received only an extremely thin film 
or coating of the precious metals, and it was highly desirable 
that the thickness should be considerably increased, on account 
of the greater degree of durability required. 
About this period, Professor Jacobi, of St. Petersburg 
(October, 1838), and Mr. Spencer, of Liverpool (May, 1839), 
published their processes of electrotype for copying engraved 
plates in copper by separate currents of electricity, by means 
of which a firm coating of copper, of considerable thickness, 
could be readily obtained. From the moment that this method 
of obtaining thick deposits of firm copper by means of a separate 
electric current was made known, Mr. John Wright, a surgeon of 
Birmingham, and Mr. Alexander Parkes, a modeller and experi- 
mentalist, in the employ of Messrs. Elkington, were constantly 
engaged in experiments, to obtain thick deposits of silver and 
gold by similar means. A great variety of liquids were tried for the 
purpose, but all the solutions of gold and silver operated upon 
gave only a thin deposit of firm metal, which, as it increased 
in thickness, became loose in aggregation, and assumed the 
character of a dark-coloured or black metallic powder, com- 
pletely useless for the purpose required. 
At this particular juncture, Mr. Wright met with the follow- 
ing-passage in Scheele’s "Chemical Essay” (pages 405 and 406). 
Speaking of the solubility of the oxides and cyanides of gold, 
