62 
ERPORT ON GIDING, ETC. 
be augmented at will, and the thickness may be estimated 
by the duration of the immersion. 
4, Galvanic Process of M. de JRuolz, for the application 
of a great number of Metals to other Metals. 
Gilding. — For applying gold, M. De Ruolz employs a 
constant battery ; but he used such a variety of solutions of 
gold, that he found cheaper and more convenient ones than 
those of Mr. Elkington. Thus, he made use of cyanuret of 
gold dissolved in the simple cyanuret of potassium., in the 
yellow ferrocyanuret, and in the red ferrocyanuret of that 
metal. He also employed the chloride of gold dissolved in 
the same cyanurets, the double chloride of gold and potas- 
sium dissolved in the cyanuret of potassium, double chlo- 
ride of gold and sodium dissolved in soda, and, finally, sul- 
phuret of gold dissolved in the neutral sulphuret of pot- 
assium. 
Even chemists must be astonished that the last of all 
these processes, — that which is based on the employment of 
the sulphurets, — is the most convenient, and that, applied 
to the gilding of metals, such as bronze and brass, whose 
sensibility as regards sulphuration is well known, it suc- 
ceeds wonderfully, giving the finest gilding and of the 
purest tone. 
Jewellers will derive great benefit from this process, but 
science will also gain much advantage. Thus, in future, 
there will be no obstacle to gilding, at a cheap rate, all the 
copper instruments which so rapidly corrode in our labora- 
tories ; we may procure tubes, capsules, and crucibles of 
gilded copper, which will be good substitutes for vessels of 
gold, which are sometimes necessary, and which no chemist 
of the present day possesses. 
Among the pieces laid before the Academy, there is a 
gilded brass capsule, which has very effectually resisted the 
action of boiling nitric acid. 
Steel and iron are very well and solidly gilded by this 
