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A Textbook of Assaying

For the Use of Those Connected with Mines

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Published: 1904
Language: English
Wordcount: 198,611 / 646 pg
Flesch-Kincaid Reading Ease: 72.7
LoC Categories: TN, LT
Downloads: 454
Added to site: 2006.07.04
mnybks.net#: 14001
Origin: gutenberg.org
Genre: Instructional
Excerpt

vals, will represent the mass from which it was taken. Taking a heap of ore, A, and selecting one out of every twenty spade-, bag-, barrow-, or wagon-fuls, according to the quantity of stuff in the heap, there is obtained a second heap, B, containing one-twentieth of the stuff of the heap A. If we crush the stuff in B until this heap contains approximately the same number of stones as A did--which means, crushing every stone in B into about twenty pieces--B will become the counterpart of A. Selecting in the same manner 5 per cent. of B, there is got a third heap, C. This alternate reduction and pulverising must be carried on until a sample of suitable size is obtained. This may be expressed very clearly thus:--

A = 1000 tons of rocks and lumpy ore. B = 50 " " rough stones, 1/20th of A. C = 2.5 " " small stones, 1/20th of B. D = 0.125 " " coarse powder, 1/20th of C.

[Illustration: FIG. 1.

CONE

PARTLY REDUCED CONE

PLAN OF FRUSTRUM DIVIDED.

ELEVATION OF FRUSTRUM DIVIDED.

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