Voelcker yielded 34.92% tricalcium phosphate, a specimen of the shale 52.15% (Report of Brit.
As the outcome of these inquiries it has been established that tricalcium silicate 3CaO S10 2 is the essential constituent of Portland cement.
The constituent of next importance is an aluminate, but whether this is dicalcium aluminate, 2CaO Al 2 0 3, or tricalcium aluminate, 3CaO-Al 2 0 3, is still in doubt.
In the following description it is assumed to be the tricalcium aluminate.
The two principal minerals are termed alite and celite; according to the best opinion, alite consists of a solid solution of tricalcium aluminate in tricalcium silicate, and celite of a solid solution of dicalcium aluminate in dicalcium silicate.