136 
IOWA ACADEMY OF SCIENCES. 
cents of the constituents of a theoretically chemically pure 
hydrated aluminum silicate with five molecules of water 
of crystallization are also given. 
South Dakota. 
Reygate, 
England . 
Quincy, Florida. 
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Silica (Si0 2 ) 
51.28% 
52.81% 
62.82% 
53 . 33% 
Alumina (Al 2 0 3 ) 
20.43 
6.92 
10 35 
22.67 
Water (H 2 0) 
20 81 
14.27 
7.72 
24.00 
Calcium oxide (CaO) 
.87 
7 40 
2 43 
Magnesia (MgO) 
.40 
2.27 
3.12 
Ferric oxide ( Fe? O* ) 
2.42 
3.78 
2.45 
Potassa (K 2 0) 
1.89 
.74 
.74 
Soda (Na 2 0) 
.54 
. 20 
Sodium chloride (NaCl) 
.48 
Sulphuric oxide (SO?) 
.57 
Total 
99 64% 
— 
100 00% 
The iron must exist in the state of ferric oxide since it is 
all dissolved out by hydrochloric acid on digesting on a 
water bath for a few minutes. The constituents: magnesia, 
lime, soda and potassa must be in the form of silicate, 
except that which exists in the form of chloride and sul- 
phate. When the silica combined with the magnesia, 
lime, etc., is subtracted from the total silica, the amount 
of alumina, water and the remaining silica is in fair accord 
with the formula, AlgO^SiGg)^ BH 2 0, 2H 2 0. How near 
this analysis accords with the formula is shown by the fol- 
lowing table. The second column of figures gives the 
amount required by theory, using the amount of silica found 
as a basis for calculation. 
FOUND. CALCULATED. 
Silica (Si O) 48.45 48.45 
Alumina fAl 2 0 3 ) 20.43 20.59 
Water (H 2 0) 20.81 21.80 
Two samples heated in the air both at 100° C. lost in 
weight corresponding to two molecules of water. It quickly 
disintegrates in w r ater yielding a whitish emulsion and on 
