tons, yielding
thirty-nine tons of carbon. Mr. Holley calculates that it equals about
150 tons of bituminous coal, such as is found in the Pittsburg region.

SOUTH CAROLINA PHOSPHATES.

In England the favorite source of phosphates of lime is the "Cambridge
coprolites." These are small, hard, gray nodules, obtained by washing a
stratum, of about one foot in thickness, lying in the upper greensand
formation in Cambridgeshire. Similar coprolites are found and mined in
other districts of England, but they are of inferior quality, containing
more oxide of iron and alumina. These give the tribasic phosphate of
lime, which results from the application of sulphuric acid to the
nodules, a tendency to "go back" to the insoluble condition. French
nodules are of inferior quality from another cause. They contain very
much silica, sometimes even forty per cent. The Cambridge coprolites are
so much esteemed that buyers of artificial manure often stipulate that
it shall be made from them. As a consequence the privilege of mining the
ground is costly, sometimes as much as $1,500 an acre being paid. The
yield is about three hundred tons to the acre. An English chemist
reports that the South Carolina phosphate, made in factories situated in
and near Charleston, ranks next in value to this Cambridge product. It
contains 54 per cent. of tribasic phosphate of lime, 14 per cent. of
carbonate of lime, 3-1/2 per cent. of iron oxide and alumina, 2-1/2 per
cent. of fluoride of calcium, and 15 per cent. of silica. It consists of
bone fragments derived from animal species which are now extinct. These
bones have accumulated in old river beds, and the mining operations are
compelled to follow the sinuosities of these streams. Though a supply
derived from such sources is necessarily limited, the quantity known to
be available is very great, and has been estimated to last a century
with a yearly extraction of 50,000 tons. In addition to the river
phosphate is a lighter deposit, occurring in a stratum of sand and clay
about two feet thick; but this is not so valuable, though it is softer
and easier ground. The river deposit is nearly black, and when ground
makes a very dark powder. It is a great favorite, and in some respects
the finest natural source of phosphatic manure in the world.

RARE METALS FROM OLD COINS.

The operations of the Government assay office in Frankfort during the
last year have developed the fact that gold, platinum, palladiu