130 
EXPOSITION AT VIENNA. 
clay, one-eighth cement, one-eighth kaolin, and one-eighth 
fire-sand. The " cement” is a burned fire-clay. 
In the best New Jersey clays no grit can be perceived when 
tested between the teeth. Analyses of good specimens show 
the following ingredients 1 :— 
1.* 
8-t 
3-t 
4.} 
Silica, 
Alumina, . . . 
Zirconia, 
Potash, 
Lime, 
Magnesia, 
Peroxide of iron, .... 
Protoxide, 
Water, 
43.20 
39.71 
1.40 
.37 
.74 
14.25 
45.30 
37.10 
1.40 
1.30 
.17 
.22 
1.30 
13.40 
46.32 
39.74 
.36 
.44 
.27 
12.67 
46.29 
40.09 
.50 
.27 
12.67 
* White clay from Burt’s Creek near South Amboy. 
t White clay from Trenton. t Cornwall, England. 
Prof. Cook, state geologist of New Jersey, says of the 
potter’s clay, that it is tenaeious, of a light-blne color; a little 
gritty when tried between the teeth. When highly heated it 
becomes partially vitrified without losing its shape, and is 
thus well adapted for earthenware. And it »can- be heated 
sufficiently for salt-glazing without injury. The following 
analyses show composition at several localities :— 
1.* 
*.t 
3.} 
4.5 
Silica, 
Alumina, 
Potash, 
Lime, 
Magnesia, 
Oxide of iron 
Water, . • 
71.80 
19.05 
.61 
.31 
.79 
1.31 
6.08 
68.00 
23.66 
1.19 
1.17 
6.40 
65.62 
20.88 
1.95 
.30 
1.23 
8.10 
75.55 
19.04 
.10 
.71 
4.85 
99.95 
100.42 
98.08 
100.25 
* Morgan clay, pits near South Amboy. 
■f Bank of Rancocas Creek, near Bridgebora. 
J Billingsport, on the bank of the Delaware, below the mouth of Mantua Creek. 
§ Raccoon Creek, a mile above Bridgeport. 
1 These and the following analyses for eomparison are taken from the Geology of 
New Jersey, 1868, p. 683. Analyses 3 and 4 from Percy’s Metallurgy.