59 
AND 
CID. 
[URIC 
10. 
o 
m 
«g 
CO _ 
0 » 
CO 
o a 
W P 
< 
^CO 
Q 
E 
F 
17.3 
73.5 
Zinc amalg. ... 
1 / .u 
o/ .u 
12.5 
54.5 to 20.0 
12.0 
4o.O 
10.0 to 3.0 
1.0 
8.0 
31.0 
O.U 
14.U to l.U 
E 
F 
Cast Iron (Rod) 
16.5 
82.0 
16.2 
54.0 
Platina (Small) 
16.0 
53.0 
Copper 
11.8 
53.0 
14.1 
50.0 
Iron (Wire) ... 
13.0 to 12.5 
27.0 to 25.0 
Do. Cleaned ... 
7.5 
§2 
CO H 
W Q 
§2 
:< 
D 
£co 
The following Paper was then read : — 
ON A REMARKABLE BOILER CRUST, COMPOSED OF SULPHATE 
OF LIME. BY WILLIAM WEST, ESQ., F.R.S. 
It has been common to speak of bicarbonate of lime, or 
carbonate of Lime dissolved in water by excess of carbonic 
acid, according to the opinions on a theoretical point, of 
authors describing the same substance, as yielding the crust 
or " fur" of steam boilers, and either to deny or overlook 
the share which sulphate of lime has in the formation of this 
troublesome deposit. Among those who have gone so far as 
to deny the existence, or at least the practical importance, of 
sulphate of lime in these crusts, is Dr. Ritterbandt, the 
proprietor of a very ingenious, and I believe in some situations 
a very effectual patent method for preventing incrustations of 
the carbonate, by introducing Chloride of Ammonium into the 
boiler. 
At that temperature, carbonate of ammonia is driven off, 
and the highly soluble chloride of calcium remains, in place 
of insoluble carbonate of lime. I have, however, so often 
found in these crusts, not merely a notable, but a considerable 
proportion of sulphate of lime, that I have on different 
