138 
TOPULAR SCIENCE REVIEW. 
with oxide of iron, when it is at once ready for shipment, chiefly 
to Kuncorn. From Kuncorn it is sent to the potteries, where it 
is used with china clay in the manufacture of porcelain and 
earthenware. 
It is not only in the potteries, however, that china clay is 
used. As stated above, more than 200,000 tons per annum are 
now exported from the two western counties, the value of which 
at the present exceptionally low prices may average, perhaps, 
11 . per ton at the shipping port. Of this large quantity pro- 
bably little more than one-third is used in the English potteries. 
Fully as much is used by the paper-makers of the United King- 
dom, and probably 20,000 tons are used by makers of alum and 
sulphate of alumina, and at least as much by “ bleachers ” of 
calico and yarn. Many thousands of tons are shipped to the Con- 
tinent for all the above purposes, and also for the manufacture 
of ultramarine. So cheap and convenient an article is also no 
doubt used to a considerable extent by adulterators and sophisti- 
cators of various kinds, but it probably only needs to be more 
widely known to be used legitimately for many purposes to which 
hitherto it has not been applied. 
We have spoken above of the 66 sand ” of the “ mica.” Now- 
adays much of the fine mica is re-washed and sold as an inferior 
“ mica clay ” for making inferior kinds of paper and pasteboard, 
but the bulk of it must still be regarded as a waste product. 
The sand is also largely a waste product, and as there are from 
three to eight tons of sand yielded for each ton of clay, large 
accumulations exist at most of the principal works. Of late 
years some of this — mixed with refuse clay — has been made into 
excellent fire bricks, for which there is a considerable demand, 
especially for the copper-smelting furnaces of Chili and Mexico ; 
but there are still millions of tons available when a proper use 
can be discovered. 
Very good building bricks have also been made from the 
discoloured clay and mica, but the heavy cost of carriage usually 
prevents the use of building bricks at great distances from the 
place of manufacture, so that, although there is a fair local 
demand, millions of tons of material are still available for any 
suitable purpose which may be hereafter discovered. 
Some of the sand is very coarse, some very fine — but in all 
cases it consists mainly of angular fragments of quartz, admirably 
adapted from their extreme sharpness for mixing with cement 
or lime for making concrete blocks, or with asphalt for pave- 
ments. 
The coarser varieties also make excellent gravel walks, as the 
small quantities of clay and mica usually present serve to bind 
the grains together under foot to form a firm roadway. 
The following analyses, selected from the writer’s paper read 
