ON THE SCIENCE OE ELEC TBQ - PLATIN C- . 
39 
the wife of Mr. Gamin ell, of Sheffield), after his death. A 
separate battery, to generate the electric current, was not em- 
ployed until January, 1841, nearly a year after the date of the 
patent; and, in the early stages of the process, the silver 
solution was employed hot; nowit is always used cold. Nickel 
silver was always the substance employed as a base for receiv- 
ing the deposit from the earliest period of electro-silver-plating, 
or at least soon after the date of Mr. Wright’s patent. The 
edges of articles are made of the best quality of nickel silver, 
which is very white and very hard, suitable for resisting- friction, 
whilst the body part, or mass of the article, is made of a com- 
moner quality, not only because it is less expensive, but also 
because it is worked more easily. 
Electro- deposition of the precious metals was theoretically 
accomplished long before cyanide of potassium was known ; as 
early as the year 1805, Brugnatelli “gilt, in a complete maimer, 
two large silver medals, by bringing them into communication, 
by means of a steel wire, with the negative pole of a voltaic 
pile, and keeping them, one after the other, immersed in 
ammoniuret of gold, newly made and well saturated.” We 
should therefore not condemn theoretical science, because we 
are not able, even with fair and persevering trial, to apply it to 
any useful purpose, but wait patiently until circumstances 
ripen for its application. Many discoveries and inventions 
which are inapplicable in one state of knowledge, become 
applicable by the progress of science and art ; the idea of 
electro-gilding, first attempted in 1805, by means of a solution 
of ammoniuret of gold, had to await the discovery of cyanide of 
potassium, in 1815, before it could be practically applied; and 
the idea of an electric telegraph, first attempted by the aid of 
frictional electricity, had to abide the development of the 
voltaic battery, and the discovery of electro-magnetism, before 
it could be successfully carried out. 
A great number of experiments had to be made, and many 
serious difficulties to be surmounted, before practical and re- 
munerative electro-plating was an accomplished fact. One of 
the chief difficulties consisted in making the silver adhere firmly 
to all parts of the underlying metal; this want of adhesion 
arose partly from the employment of too many cells in the bat- 
tery, and partly from the use of too strong mercurial solution 
in preparing the surface, and was eventually overcome by less- 
ening the number of cells, and dipping the previously cleaned 
articles in a very weali solution of mercury immediately before 
placing them in the plating liquid. If the deposit of silver is 
not firmly attached to the whole of the surface of the article, it 
is apt to rise in blisters and peel off when the articles are sub- 
jected to the after-process of burnishing. This non-adhesion 
