Smyth — Talc Industry' of St. Lawrence County. 667 



their product over the recently constructed Gouverneur and Oswegatchie 

 railroad, to mills scattered along the Oswegatchie river, which furnishes their 

 motive power. 



The process of manufacture is purely mechanical, having for its aim the 

 reduction of the talc to a fine powder of uniform grain and free from grit. 

 On account of its fibrous structure, the talc, when powdered, has a strong 

 tendency to pack into a sort of felt. For this reason it can not be bolted, 

 and special methods of treatment are required. 



The process begins with a sorting of the material at the mines, where the 

 hard and darker-colored pieces are thrown out. The good talc, in lumps 

 ranging from a foot or more in diameter down to coarse powder, is then 

 loaded on cars and shipped to the mills. Here it passes through Blake 

 crushers, and then goes to rolls or burr stones and is reduced to grains about 

 the size of a pea. 



From the rolls or burr stones, the talc goes either to Griffin mills 

 or direct to the Alsing cylinders. These are drums of half-inch steel, six 

 feet in diameter and ten feet in length. They are supported by trunnions 

 at the ends, and revolve about twenty-five times a minute. The cylinders 

 have a lining of glazed brick, and in each one are placed some three and one- 

 half tons of round flint pebbles, about the size of an egg. A cylinder is 

 charged with an amount of talc equal to one-quarter or one-third the weight 

 of flint pebbles and, after the manhole is closed, is revolved till the talc is 

 reduced to the requisite degree of fineness. This operation usually takes 

 about two hours. When it is completed, the closing plate is removed and a 

 grating substituted, which will retain the pebbles and permit the discharge of 

 the talc. The cylinder is then revolved again till the talc is all removed, 

 ready for packing and shipment. 



Several grades of talc are produced, varying in fineness and- color. 

 Extreme and uniform fineness and a blue- white color, are the desirable 

 qualities. The fibrous structure is found in all grades and is, doubtless, a 

 most important factor in giving value to the material. The felting of the 

 powder, which gave much trouble in the earlier attempts at manufacture, is 

 the foundation of its most extensive application. Under the microscope, even 

 the finest and most impalpable portions of the powdered talc are seen to con- 

 sist of ragged, fibrous masses, elongated in the direction of the fibres, and 

 frayed and shredded at the ends. It is evident that the fibrous structure 

 is present on so minute a scale as to extend to the finest particles of the 

 mineral. 



