The Mineral industry Volume 17 - Tapa blanda

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1909 Excerpt: ... massive forms, and in an earthy, amorphous form. Molybdenite is often mistaken for graphite, but a distinction can easily be made by comparing the relative weights, molybdenite being about twice as heavy as graphite, while its streak and color are more dull and lead-gray. Finally the blow-pipe will show that graphite is infusible, while molybdenite gives a sulphur reaction. The distinction can also be made with nitric acid, which dissolves molybdenite, but has not the slightest effect on graphite. The occurrences of graphite in the United States are numerous. It is spread over the entire country and is found in nearly all formations, from the old Laurentian to the younger coal measures, although the most and best deposits occur in the older crystalline and non-fossiliferous rocks, and the ancient metamorphic schists. But frequent as are the occurrences of graphite, the number of deposits that can be worked with a prospect of profit is small, most of them suffering from lack of sufficiency in quality or quantity, or both. The trade has divided graphite into two general classes, viz., the crystalline and the amorphous. Some scientists have recently attempted to introduce a new classification, based on the behavior with hot nitric acid and potassium chlorate. On the basis of the yielding or indifference of graphite to that acid reaction these scientists established a rule for the division of all graphites into two classes, calling the ones which yield, ' graphite,' and those which do not,' graphitite.' According to this rule, the graphites from Ticonderoga, N. Y., and Clay county, Ala., are real graphites, while the graphite from Raton, Colfax county, N. M., and the artificial graphite from Niagara Falls are graphitites. Interesting as this new classification...