No. 275.J 
41 
cious. The carbonate of lime is white, and forms a handsome ground 
for the translucent serpentine.* 
64. Usually associated with serpentine, when it occurs in extensive 
beds, is a mineral which has nearly the same chemical composition, ge- 
nerally known by the name of soapstone. This is particularly the case 
in the counties of Richmond and St. Lawrence. In consequence of its 
softness and tenacity soapstone may be turned or cut into articles of va- 
rious shapes, and rendered hard by exposure to heat. It is hence much 
used for the hearths of furnaces, the sides of fire places, the linings of 
stoves, and for similar purposes. 
65. Another substance often found with these magnesian minerals is 
asbestus, under which I include the variety composed of flexible silky 
fibres, sometimes known by the name of amianthus, there being no line 
of specific distinction to warrant its separation. This mineral has ac- 
quired notoriety from the fact that some of its varieties may be woven 
into cloth which is indestructible by heat. It is to uses similar to these 
that it is accordingly applied, being employed in the preparation of the 
incombustible cloth proposed for firemen's robes, and for the lining of 
the metallic safes now so generally introduced into counting houses. 
Materials for the manufacture of Porcelain. 
66. The localities of clays suitable for the manufacture of brick and 
the common kinds of earthern ware, are too numerous in this State to 
be at present noticed, and their description belongs rather to the depart- 
ment of geology than to that of mineralogy. Many of these have al- 
ready been noticed in the reports of the geologists, and Prof. Mather 
has presented some details which show the importance of the branch of 
industry included under the art of brickmaking. 
The manufacture of the finer kinds of pottery has not heretofore been 
carried on with much success in our country. Whether this be owing 
to the superior facilities which are possessed by the English and French 
in regard to materials, or to the reduced price of labour, it is not easy to 
determine. My present object is merely to show that New-York is not 
destitute of the materials necessary for this branch of art. 
The finer kinds of pottery require for their manufacture the purest 
clays, — such as contain little or no oxide of iron and which consequent- 
ly do not turn red in burning. To these a portion of pure silica is ad= 
ded, which is prepared for the purpose by heating masses of flints or 
* Prof. Emmons' Report for 1838. 
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