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CONDUCTED BY WILLIAM AND ROBERT CHAMBERS, EDITORS OF 'CHAMBERS'S INFORMATION FOR THE PEOPLE,' 'CHAMBERS'S EDUCATIONAL COURSE,' &c.
| No. 422. NEW SERIES. | SATURDAY, JANUARY 31, 1852. | PRICE 1½d. |
WIRE USED IN EMBROIDERY.
In the manufacture of embroidery fine threads of silver gilt are used. To produce these, a bar of silver, weighing 180 ounces, is gilt with an ounce of gold; this bar is then wire-drawn until it is reduced to a thread so fine that 3400 feet of it weigh less than an ounce. It is then flattened by being submitted to a severe pressure between rollers, in which process its length is increased to 4000 feet. Each foot of the flattened wire weighs, therefore, the 4000th part of an ounce. But as in the processes of wire-drawing and rolling the proportion of the two metals is maintained, the gold which covers the surface of the fine thread thus produced consists only of the 180th part of its whole weight. Therefore the gold which covers one foot is only the 720,000th part of an ounce, and consequently the gold which covers an inch will be the 8,640,000th part of an ounce. If this inch be again divided into 100 equal parts, each part will be distinctly visible without the aid of a microscope, and yet the gold which covers such visible part will be only the 864,000,000th part of an ounce. But we need not stop even here. This portion of the wire may be viewed through a microscope which magnifies 500 times; and by these means, therefore, its 500th part will become visible.—Lardner's Handbook.