STATE GEOLOGIST. 201 
cements showing the interlacing crystals of lime hydrate and lime-alumina 
silicates forming the hardened cement. Beside these, crystals were found 
strongly resembling nephrite. But the main active constituent, according 
to Liamin, is the lime hydrate which forms crystals frequently 1 mm. 
long. In hardening, the crystals of calcium hydrate and the nephrite- 
like crystals increase in magnitude. The anhydrous cement contains 
practically all of the lime combined, the principal mineral present being 
probably the sub-silicate of lime, which in hydration breaks up into a 
simpler silicate and calcium hydrate. The two methods of quantitative 
separation of the different constitutents adopted by Liamin were: 
1. Mechanical separation of the ground, hardened, cement by 
means of solutions of varying specific gravities. 
2. Determination of the water of hydration at different temperatures. 
Liamin made the assumption that the water of hydration of the hydro- 
silicates leaves at 160° C., while the calcium hydrate loses its water between 
450° and 480° C., an assumption by no means proven. 
The liquids employed by this investigator in making the mechan- 
ical separation of the different minerals of the cement were: 
a. Yellow methyl iodide, specific gravity 3.34 
b. Benzene, specific gravity 0.89 
By means of a mixture of these liquids of 2.3 specific gravity the lime 
hydrate was washed out and washed free from other constituents by 
means of the benzene. No trouble was experienced in removing the 
calcium hydrate, owing to the close specific gravities of the hydrate, 2.18, 
and of the liquid, 2.3. The amount of calcium hydrates thus obtained 
he checked by means of the second method. By determining the amount 
of water expelled at 160° C., and the quantity set free at 480° the amount 
of free calcium oxide can be calculated, for 18 parts of water correspond 
to 50 parts of the oxide. If thus 
a=total loss of weight on igniting the hardened cement, 
b=the loss of hygroscopic water at 100°, 
c=the loss of water of hydration at 160°, 
d=content of carbon dioxide and, 
e—water content of the calcium hydrate, 
e=a—(b-+c+d), and 
molecular wt. calcium hydrate 74. 
@ << ee = 4 TI KX e=—tOtal amount OF 
molecular wt. water 18 
calcium oxide in the Portland cement. 
Liamin found in 5 Portland cements 
after 7 days hardening from 13.2 to 22.9 per cent. CEC OIE) 
after 28 days hardening from 26.3 to 32.3 “ “ 
after 60 days hardening from 30.9 to 33.1 
after 180 days hardening from 31.6 to 33.6 
after 365 davs hardening 22,0 
66 66 (3 
ce 66 66 
