206 ANNUAL REPORT 
which interferes with the hydration of any lime present. The alka- 
lies, Fuchs says, have no influence upon the hardening. | 
The Work of Chatelier.—The synthetic work of Chatelier* may 
be summarized as follows: 
Wollastonite, mono-calcium silicate, which is ‘a mineral found in 
nature, is not hydraulic. The di-calcium silicate 2CaOSiO,, made by 
heating an intimate mixture of calcium carbonate and quartz, disin- 
tegrates spontaneously on cooling, which evidently is due to a molecular 
change. The tri-calcium silicate, 3CaOSiO,, he claims, cannot be ob- 
tained by direct synthesis. When made by heating silica with lime, 
more or less free lime always results. But it may be formed indirectly 
by crystallization from a magma of more fusible compounds of silica, 
alumina, lime and iron oxide. This compound is the basis of hydraulic 
activity in Portland cements. The mono-calcium aluminate CaOAl.O, 
is almost infusible. It shows hydraulic activity. The di-calctum alu- 
minate (2CaO)AI,O, is quite fusible and sets when made up with water 
quite rapidly. It shows, however, a great tendency to disintegrate after 
hardening. | 
The tri-calcitum aluminate (3CaO) AIl,O, is decidedly fusible and sets 
rapidly. The lime-iron compounds all slake with water, and are not 
hydraulic. According to Chatelier, hardened cement consists of hex- 
agonal crystals of lime hydrate, surrounded by a white mass of needle- 
shaped hydrous mono-calcium silicate, CaOSiO,2.5H,O. The reaction 
of the hardening process corresponds to the following equation: 
3CaOSi0,+xH,0O=2CaO (OH ),+CaOSi0,2.5H,0O. 
The Work of the Messrs. Newberry.—Of more recent investiga- 
tions that of S. B. and W. B. Newberry** is one of the most exten- 
sive. Jin their article on “Ihe Constitution of Hydraulic Cement,” the 
title of which, however, is a misnomer, as the constitution of the 
hydraulic compounds was not touched upon, but only the range of com- 
position was considered, a number of synthetic bodies were prepared. 
These were made by mixing dry, without grinding, almost pure silica 
alumina and calcium carbonate, moistening, and making into small pieces. 
These were burnt in a Fletcher pot furnace, fired with gasoline, provided 
with a Portland cement lining. The temperature reached in this furnace 
was probably quite high, but it is to be regretted that no attempt was 
made to measure it by means of Seger cones or other means. 
These investigators endeavored to determine the presence of free lime 
by subjecting the pats made from the cements to the action of steam at 
98° C. for four or five hours, after allowing the cement to stand over 
& *Ann. des Mines 1887, 345. 
*k Tournal Society Chemical Industry, Vol. 16, No. 11. 
