40 
POPULAR SCIENCE REVIEW. 
of the silver was particularly apt to occur with articles made of 
Britannia metal, and with this particular alloy it was not over- 
come for several years; it was then effected by first coatiug the 
articles with copper, by electro process, in a solution composed 
of sesquicyanide of copper dissolved in an aqueous solution of 
cyanide of potassium, a liquid invented by Mr. Wright for the 
purpose of coppering articles of iron previous to silvering them, 
and patented in September, 1841. The method now in use for 
coating Britannia metal is different ; it consists in first forming a 
thin deposit of silver upon the article, by a powerful battery, in 
a solution containing but little cyanide of silver and much 
cyanide of potassium, thus transferring the article to the ordinary 
silver-plating liquid, and completing the deposit therein in the 
ordinary maimer : this process was first employed by Mr. 
Thomas Fearn, from whom it was purchased by Messrs. Elking- 
ton for a considerable sum of money. 
Another difficulty arose in a tendency of the deposited silver 
to assume a granular or semi-crystalline state upon the surface 
of the articles, especially at their edges, during the process of 
deposition ; this was overcome by employing proper proportions 
of the ingredients in the plating solution, and carefully adapt- 
ing the power of the battery to the size of the articles. In 
addition to these difficulties another w r as experienced ; the 
articles after being plated and finished, in a few months became 
much discoloured : this was a consequence of too rapid deposi- 
tion. And a still more serious difficulty, which required several 
years to surmont, arose from the opposition of the manufac- 
turers of plated wares of Sheffield to the new method of plating ; 
they objected to take licenses for the new process; but now the 
electric method is the only one they employ. A dispute also 
arose between Messrs. Elkington, of Birmingham, and Ruolz, 
of Paris, the latter having’ obtained a knowledge of the process 
and taken out a patent for France a short time before Messrs. 
Elkington, and a trial at law resulted, in which it was esta- 
blished that Messrs. Elkington were the original patentees of 
the cyanide of potassium solution, and it was finally settled by 
a compromise between Messrs. Ruolz and the patentees for the 
use of the process. In consequence of these and other diffi- 
culties, it was at least seven years before it became both prac- 
tical and remunerative. 
In electro-plating the deposited metal spreads as readily 
over the most elaborately engraved or figured surfaces as 
over the plainest forms, and in consequence of this property 
the new process caused a new and great extension of trade 
in plated articles to spring up, because articles of compli- 
cated forms, or with elaborate designs upon them, could not be 
made by the old method without very great expense. By the 
