428 JOSEPH HYDE PRATT 



especially those on the hillsides, can be worked advantageously 

 by means of open pits, the majority of them are worked to 

 the best advantage when shafts or tunnels and drifts are used. 

 Little blasting is necessary at any of the mines, as the talc can 

 usually be removed readily by pick and gad. As the rough 

 blocks of talc are taken from the mine they are hand cobbed 

 if necessary and sorted into three grades. The larger pieces 

 are cleaned by rubbing them with steel brushes, and the smaller 

 ones by a founder's scouring machine. They are then dried 

 by being spread over a floor of steam pipes, which are kept at 

 a temperature of 212° F. When these pieces are dry they 

 are crushed and ground by means of crushers, rolls, and pul- 

 verizers, and the foreign material removed by screening. It 

 is then further ground in buhrstone mills, similar to those 

 used in grinding wheat, and passed through bolting cloth 

 which makes the final product nearly uniform in grain. This 

 ground product is handled very much like flour, and in filling 

 the bags with the flour talc, an ordinary flour packer is often 

 used. 



In Maryland, New Jersey, Pennsylvania, and Virginia, 

 where it is principally the steatite variety of talc that is pro- 

 duced, the mining operations are carried on almost entirely 

 in very large open cuts and pits. The preparation of the 

 ground talc from the New Jersey and Pennsylvania mines or 

 quarries is a process similar to that described above. In Vir- 

 ginia, where the soapstone is used almost exclusively for manu- 

 factured articles, the tonnage mined is of course very much 

 larger than the weight of the articles manufactured and put 

 on the market. 



Talc is employed in the arts in two distinct forms, as 

 powder, or flour talc, and as pieces sawed into various sizes 

 and shapes. The flour talc is now used as a base for fireproof 

 paints, lubricants, and many of the cheaper soaps, for electric 

 insulators, for boiler and steam pipe coverings, for foundry 

 facings, for the dressing of skins, and in the manufacture of 

 dynamite, of the various toilet powders and of paper. For- 

 merly certain varieties of clay were used as a filling in the 

 manufacture of paper, but with the discovery of large deposits 

 of talc, especially of the fibrous variety, in New York, talc has 



