64 ANNUAL OF SCIENTIFIC DISCOVERY. 



silver, in a bar twenty inches long, stretch over five hundred miles. But as 

 the four hundred ounces of silver is gilt with only eight ounces of gold leaf, 

 each leaf weighing eighteen grains, and four inches square, it follows that 

 only one-fiftieth part of the wire is gold. So eight ounces of gold in com- 

 bination with silver, is made to stretch five hundred miles, or over sixty 

 miles for a single ounce. As, from first to last, the wire passes through one 

 hundred to one hundred and twenty dies, it follows that the ingot in its 

 course traverses over fifty thousand miles, or twice the circumference of the 

 globe. 



In London, he believed that five hundred ounces of metal could be drawn 

 into wire, while fifty arc drawn at Pactun. In London it can be drawn 2,000 

 or even 2,200 yards to the ounce, while in Pactun they stop short of 1,000, 

 or 1,200. 



For many years chemists have attempted every known method of gilding, 

 in the hope of discovering some process by which silk, or other fibre, could 

 be gilded without applying the immense labor, seen to be necessary, before 

 a thread with a covering of gold can be used with facility in the loom, and 

 woven into cloth ; but they always failed. In France, where scientific re- 

 search is liberally promoted by the government, a large reward was offered 

 for a successful plan, but no man ever had the opportunity or satisfaction 

 of claiming it. The electro process gave a fresh impulse to scientific 

 men. 



The difficulties of the first stage were soon overcome, and gold was com- 

 pelled to attach itself to the surface of the thread. A new difficulty arose 

 the thread, being completely soaked, was long in drying, and when dried, 

 had lost its lustre ; while the foundation on which the gold rested was so soft 

 and flimsy, that to burnish it was impossible. Among the several investi- 

 gators was Mr. Albert Hock, who, failing to find in chemistry the principle 

 by which fibres could be gilded, succeeded by means of a simple mechanical 

 contrivance. 



The author said he had felt how difficult it was to find words calculated to 

 explain the simplest mechanical movement, and then the difficulty increased 

 a hundred fold. In the first place, it is essential that the silk used should 

 be of a superior quality, free from knotty nibs and rough places. The gum 

 must be boiled out of the silk, and then the silk tinged to the shade of a light 

 orange ; it is then wound on bobbins, the bobbins are placed on a wire, on 

 which they revolve when gently pulled. The end of the thread is passed 

 over a wire, and then under a roller, which works in a trough containing a 

 glutinous but transparent liquid. It then passes over a reel attached to an 

 endless screw or threaded spindle, so arranged that it lays on a brass cylin- 

 der, the thread of silk as close as cords arc wound round the handle of a 

 whip, without overlapping, until the cylinder is completely covered with the 

 silk, when the thread is broken ; the length of the skein of thread depends 

 therefore, upon the size of the cylinder and fineness of the thread, but the 

 cylinder cannot be increased beyond a certain size, and that size must, not be 

 larger than can be spanned by a single leaf of gold, and the gold-beaters will 

 not produce it larger than three and three-eighths of an inch square. The cylin- 



