While adulterated asbestos may be used in some of the mechanical arts, for theatrical hang ings its purity should be 100 per cent; it then forms one of the safest barriers against the calamity of fire. As a matter of fact, much of that which is termed commercially pure asbestos cloth contains from 5 to 20 per cent of com bustible matter, but absolutely pure Amer ican-made cloth may be obtained. Not only is purity essential in asbestos cloth where used for protection against fire, but strength as well; and after asbestos is subjected to a high tempera ture, it has a tendency to powder, when, owing to its weight, it may break through, and its utility be impaired.
One of the leading manufacturers has made an improvement in weaving asbestos cloth for theatre curtains; it consists of two strands of asbestos spun around a strand of high-tempera ture-melting brass wire, so that the wire is completely embedded and concealed. These as bestos metallic strands form the warp, so that the threads run the long way the cloth when finished. The weft, or filling-in cross threads, is made of plain, pure asbestos. Such a curtain will stand well under a severe high-tempera ture test without breaking. Not only theatre curtains, but set scenery of all kinds may be constructed of asbestos. Scenic artists find it more difficult to paint, but the finer textures may be utilized for this purpose; and although asbestos cloth does not take colors as satisfac torily as cheese cloth and burlap, yet its use should be provided for wherever audiences are to be assembled. Flooring and woodwork in general may easily be replaced by compressed asbestos fibre board, and it has been shown that the latter may be stained, polished and finished to as high a degree as wood. All the upholstery should be of pure asbestos cloth, and carpeting is also made to take the place of the combustible vegetable and animal fibres now used so extensively. One of the peculiar prop erties of asbestos carpeting is that the longer it is in service, the tougher it becomes.
Asbestos is utilized in the arts in many other forms than cloth; it may be worked into a pulp, and a fireproof paper is obtained. This paper is now used on roofs, between walls, flooring, etc. Fireproof rope three-eights inch in diameter for the suspension of curtains and other uses is made, having a tensile strength of 1,650 pounds per foot. High-grade asbestos plaster is fire proof, sound-proof, and hangs together with great tenacity when subjected to water.
In the United States asbestos is produced in five States—Arizona, California, Idaho, Georgia and Virginia. Of these Arizona and Georgia
yield the largest output; Arizona of high grade fibre, and Georgia of fibre below the spinning grade. The asbestos of Arizona is chrysotile, and occurs in serpentine associated with lime stone altered by intrusions of diabase. The strata are nearly horizontal, and are exposed along the walls of canyons throughout the State. The asbestos is worked out by tunneling into the canyon wall. Two grades are secured; one very fine and silky, of first-class spinning quality, and the other harsh, splintery and quite unsuited for textile purposes. Both qualities are found in the same mine. The Arizona asbestos has a much smaller percentage of iron than the Canadian staple, and is, therefore, ,better adapted for electrical insulations. In Georgia the asbestos mine near Sall Mountain has been for years the largest producer of asbestos in the United States. Only the sur face pe6rtion of the deposit, which has been softened by weathering, is milled for fibre; the deeper lying rock is too hard.
California, Idaho, and Virginia produce no fibre of spinning grade, and their output is small. It is used chiefly for making fibre board and heat insulation, and as a filler for fire proofing cements, plaster and paints.
An undeveloped source, considered of great possibilities, is the area of asbestos-bearing rocks of Vermont, an extension of the noted deposits of the Quebec region of Canada. Enough work has been done in this section to demonstrate its potential value.
The marketed production of asbestos in the United States in 1916 was 1,479 short tons, valued at $448,214. In addition to this supply, 114,978 tons of raw fibre, valued at $3,069,617, were imported from Canada; 1,072 tons, valued at $223,228, from England; and 112 tons, valued at $10,625, from British South Africa. There was also imported a value of $135,064 in manu factured articles of asbestos, nearly all of which came from England. The asbestos mines of Quebec were extremely active in 1916. Their shipments amounted to 133,339 tons, valued at $5,182,905; of which the United States bought 86 per cent. The 'market, however, was so scantily supplied that prices rose from the aver age normal of $350 to $400 per ton for high grade fibre, to $1,250 per ton, and in some cases much higher; and even the low grade short fibre brought 100 per cent more than its usual price. (See MINERAL PRODUCTION OF THE UNITED STATES). Consult Cirkel, F.,