FEATHER-ALUM— GILPIN. 179 
Sulphate of Alumina, adding an Alkali Sulphate and crystallis- 
ing the resulting salt. 
Domestic records show that through long ages the natural 
supplies of Copperas and Alum equalled the demands of the dyer 
and manufacturer. When this source was no longer adequate 
the chemist showed how the slow operations of nature could be 
hastened, and now these useful chemicals are produced with 
readiness, and at a price formerly deemed unattainable. 
These minerals, however, are highly interesting from a differ- 
ent stand-point. Hitherto we have regarded them as the source 
of agents which have become indispensable to our comfort, and 
literally the foundation of many of the varied hues that man 
affects in his dress. But the study of their origin and natural 
transmutations give an instructive insight into some of the 
changes that are continually going on in the earth. We see 
them marking several of the alterations which have led to the 
disintegration of rocks, the formation of soils, of economic 
ores, ete. 
In conclusion I may mention that the manufacture of these 
commercial Salts has not been undertaken in Canada. The 
total value of textile fabries, which may call for various pro- 
cesses of dyeing, manufactured in the Dominion, was according to 
the last census nearly $20,000,000. 
There would therefore appear to be a field for the manufacture 
of these Copperas and Alum Salts, in this country, and some of 
the shales of our coal fields may be found well adapted for the 
purpose. 
