"156 GEOLOGICAL RECONNOISSANCE 
A Carbonic Silica and 3 Alumina 
Oxide of : = Peroxide : ’ 
zine. an ‘Glteatbe of iron. ca 
ye Say * wv ee ee rain’ aan 
XR _, 
YY 
1 48-950 30-271 18-805 1-974 
2 33-149 23-612 31-069 11-361 
3 56-099 30-717 8-831 4-805 
x w 
: an 
4 53-331 32-150 14-519 
ae aye _, 
5 61-753 35-759 0-501 1-987 
XR aye J 
6 57-250 35-911 6-839 
7 56-445 39-267 8-298 
8 59-770 28-182 7-523 3-507 1-018 
9 65 - 967 31-454 1-512 trace 1-067 
ae 7 a: 
10 49-77 31-22 20-48 
11 27-02 26-63 16-58 10-86 19-79 
12 39-15 30-36 0-35 17-40 12.74 
13 42-12 30-35 8-42 1-49 17-60 
ee =) 
a a 
14 48-07 33-49 18-03 
15 60-97 10-32 18-79 9-52 1-67 
eet SF 
aA 
16 39-11 62-00 
17 36-22 62-28 
18 55-04 44-54 
19 55-59 45-56 
20 48-23 50-69 
21 63-06 35-06 1-58 0-34 
The smelting of zinc from these ores, although not quite as simple a 
process as the smelting of lead from galena, offers no difficulties: the ore, 
reduced to a proper size, is simply mixed with a sufficient quantity of coal, 
and heated, in a closed vessel, to a temperature high enough to cause the 
reduction of the oxide; the metal, being volatile, distills over and is col- 
lected in a receiver. The execution of the process varies somewhat in 
practice; at present, three methods are principally in use, known as the 
English, the Belgfan, and the Silesian method, each possessed of its pecu- 
liar advantages and disadvantages. 
The only preliminary operation which the ores are subjected to, besides 
the necessary sorting and bruising, is the calcination, (and even this opera- 
tion is sometimes omitted in England). The calcination is generally per- 
formed in reverberatory furnaces, and has the object of removing carbonic 
acid and water, and lessening the cohesion of the ore; it is a necessary 
operation if the carbonate of zinc contains blende, to convert the latter 
into oxide of zinc; in this case, a small proportion of coal must be added. 
