A method of drawing extremely fine wires
The author refers to Musschenbroek for an instance of a gold wire, recorded to have been drawn by an artist at Augsburg so fine, that one grain of it would have the length of 500 feet. It is not said how this was effected, and some doubt has been entertained of the possibility of it ; but the author of this paper shows how gold may be drawn to the same degree of fineness, and also that platina may be made with great facility much finer than is above described. The general principle of the method is the same for both. The metal intended to be drawn is first reduced, in the common mode, to a wire of about the of an inch in diameter; and it is then coated with silver, so as to form a rod of considerable thickness. The rod is then drawn, as usual, till it is reduced to a slender wire, and it is presumed that the gold or platina contained in it is reduced in the same proportion as the silver. By steeping for a few minutes, in nitrous acid the silver is then dissolved; hut the gold or platina remain unaffected, and require merely to be washed in distilled water in order to free them from any portion of the solution or other little impurities that may adhere during the solution.