m 
Brass* 
procured, which he says will be of a very superior quality 
to that procured from copper and calamine alone* 
This process like most other patent specifications, re- 
quires explanation. 
1* It is evident that the pots must be furnished with 
covers otherwise the zinc will sublime and be wasted. 
2. The degree of heat is not mentioned, whether the 
copper should be quickly melted or not, which in the 
common process for making brass does not take place till 
the latter end of the process. 
3. Much must depend on the analysis of the calamine* 
Some calamine contains lead, all contain iron. Calamine 
varies in its contents of zinc from 45 to 65 per cent. Ac- 
cording to Watson, calamine from Poland yielded out of 
16 parts 2 parts and an half : from Breslaw 4 parts and an 
half : from Hungary 2 parts and one-third : English ca- 
lamine three parts ; another specimen from Holywell in 
Flintshire 7 parts. 
I copy the following from 2 Jamison’s Mineralogy 
413. Calamine English. 
Front Holywell. Derbyshire. Somersetshire. Wantockheal. 
Ox. of zinc 65 
65.2 
648 
66 
Ox. of iron 1 
S3 
Carb. acid 28 
348 
35.2 
Water 6 
100 
100 
100 
100 
German Calamines from Fribourgh 36 oxyd of zinc* 
52 silica, 12 water : from Bleyberg / 1.4 oxyd zinc, 13.5 
carbonic acid, 15.1 water. 
Hence according to the analysis of Jamison in this pro- 
cess of Emerson’s, ten pounds of calamine may be sup- 
posed to yield six pounds and a third of zinc, which with 
three of granulated zinc for each pot will make thirty 
pounds and one-third of zinc to fifty-four of copper : if 
the produce be 82 lbs. then two pounds and one-thir# 
