76 
might be invidious to parties engaged in the making of 
fire-bricks, in a commercial point of view, and therefore I 
shall merely indicate each specimen by letters : — 
A 
B 
C 
D 
E 
F 
G 
H 
I 
K 
L 
Silica .... 
43.0 
46.2 
63.7 
83.29 
82.48 
68.05 
65.10 
63.87 
62.79 
47.54 
70.25 
Alumina . 
. 40.9 
30.8 
20.7 
8.10 
8.60 
18.85 
22.15 
20.96 
17.95 
29.51 
16.90 
1.3 
J- 2.99 
.70 
.40 
1.62 
1.74 
1.27 
Magnesia . 
0.1 
'.80 
.84 
.82 
Iron Oxides trace 
8A 
10 
1.83 
0.22 
5.20 
1.95 
.75 
.19 
7.93 
4.00 
Water 
. 14.7 
14.2 
10.3 
3.64 
8.30 
6.00 
10.00 
11.68 
14.77 
12.29 
7.10 
Potash . . . 
0.4 
i.3 
00.10 
00.40 
1.20 
i'.so 
L86 
\*99 
'.48 
100.0 1 00.0 100.0 100.00 100.00 1 00.00 100.00 100.00 100.00 100.00 100.00 
The amount of water was estimated by drying each of the 
samples at 100° Fahrenheit, until it ceased to lose further 
weight, each being previously dry to the touch. 
In order to ascertain the degree of fusibility of each kind 
of clay, I first baked or burnt a piece to the state of an 
ordinary fire-brick, from which portions were chipped off 
so as to present several sharp angular edges. These were 
placed in a crucible, lined with powdered charcoal, and 
afterwards heated in a wind furnace, heated to the fullest 
extent possible for some time. After allowing the crucible 
and its contents to cool, the pieces were taken out and 
examined ; the comparative value of each being estimated 
according to the degree it had resisted fusion, as shown by 
the thin edges of the broken piece being rounded or 
rendered translucent. To denote this, I arranged each 
according to a scale ranging from 0 to 10, the lowest number 
in the scale indicating the highest degree of resistance to 
fusion. In this manner I obtained the following results 
from the specimens given in the table of the analysis 
of each : — 
A BCD EFGHIKL 
Degree of fusibility .. 46181221765 
In a similar manner I denote the power of each, of resisting 
sudden changes of temperature without cracking. For this 
purpose a crucible was made of each kind of clay, and 
