204 ANNUAL REPORT 
Michaelis, Feichtinger, Erdmenger, Dyckerhoff, Meyer, Hauenschild and 
others. Synthetic work of a high order was also done later by Chate- 
lier, mentioned above in connection with his microscopic research. It 
will be impossible to consider the work of all these investigators, but it 
is the intention of the writer to cite a few in order to show the way 
in which the problem has been attacked. . 
The Work of Schott.——The experiments of Schott,* though not of 
recent times, deserves recognition inasmuch as he has brought out one or 
two important facts. He made up a mixture of pure silica, alumina, 
ferric oxide and calcium carbonate, whose composition after burning 
was as follows: 
Number of mixture 1 2 | 3 4 
Silica (oa ee eee mS | We | we 24.3 
ANITVENUNE go0050005500800| ge Eaters Bae Par et 6.9 6.9 
INGIBBKG ODICOscccoceosucccce Py orcrevtoee. oS 11.4 Al 7 4.8 
ENING stiteetaea toe ee 64.8 64.8 65.4 64.1 
On burning them to incipient white heat, finely grinding them and 
making up with water, they all hardened exceedingly well, even No. 2, 
containing no alumina. On adding 1.5 per cent. of caustic soda to No. 2 
it became a brown mass of extraordinary hardness. ‘To cements 3 and 
4 still more lime was added, 7.7 and 8 per cent. respectively, whereupon 
they broke down to a powder, which, however, when again made up 
with water resumed the hardening process. 
Up to about 1885 the various theories advanced defined in a more or 
less definite way the chemical composition of the cement, but all that 
practically resulted from these older investigations was the mention of 
the fact that calcium oxide formed with silica and alumina basic silicates 
and aluminates which on the addition of water harden by breaking 
down to simpler compounds and free calcium hydrate. Some of these 
experimenters also realized that the end products of the hydration reaction 
are largely colloids. 
Various Investigators.—Seftstroem produced fused masses of alu- 
mina and lime corresponding to 3CaOAI,O, : 3CaO2Al,O, and CaOAl,O,, 
by burning them in a forge. Winkler produced a rapidly hardening 
mass, which, however, broke down to a powder, by heating I1 equiv- 
alents of lime, 1 equivalent of potash and 4 equivalents of alumina to 
incipient vitrification. On hardening the mass showed considerable heat- 
*“Dingl. Polyt. Jour,” 202, 484 and 513. 
