156 ANNUAL REPORT 
Two investigators, Keiser and Forder, endeavored to determine the 
free lime by estimating the water taken up in the hydration of the cement 
during the first short interval of the setting, claiming that the calcium 
oxide 1s practically all hydrated in a short time, while the calcium silicate 
requires a much longer time. 
The study of the dehydration proccss of cements has been taken up 
by a number of investigators like Bauschinger, Rebuffat, Zulkowski, New- 
berry and the writer, but the result has been far from satisfactory, owing 
to the physical conditions which interfered with accurate work. However, 
by using suitable precautions and refinements of operation, there is no 
reason why accurate and consistent determinations should not be made. 
The main difficulty so far has been the density of the test pieces, which 
on the one hand did not permit of complete hydration, and on the other 
hindered the expulsion of the water of hydration. 
The condition of the iron in cements has been one of the points 
in dispute, but numerous determinations made have shown that the iron 
is principally in the ferric condition. This investigation is an interesting 
one and should be more thoroughly worked out for American cements. 
Three students in the laboratory of the writer in examining three standard 
American cements burnt in the rotary kiln found likewise most of the 
iron in the ferric condition. 
Of practical as well as theoretical interest is the question of the 
sulphur in cements, the changes it undergoes in the burning process and 
the rapidity with which the sulphur of the fire gases is taken up by the 
basic cement mixture. 
Theoretical experiments as to the alkalinity of cements might prove 
to be of interest and might be carried on along lines similar to the work 
of W. Richter, who, for instance, found that well burnt properly propor- 
tioned cements do not react with phenol phthalein. 
On the physical side, much work remains yet to be done. Some 
important physical constants of the cement constituents are still lacking, 
such as the determinations of the melting points, the heats of solution and 
hydration, and the miscroscopic study of the principal minerals in the 
cement slag has not been carried as far forward as should be done. 
Since the advent of practical electrical furnaces for high temperatures no 
imsurmountable difficulties stand in the way of such research. 
In closing the subject of the chemical and physical examination 
of Portland cement materials a few words may not be out of place in 
regard to the status of the American cement chemist. ‘There is a more 
or less well defined tendency in American cement plants to slight the 
position of chemist by the paying of insufficient salaries, and hence the 
places are sometimes filled by men with very little technical training 
beyond the routine of the analytical work. As a result, we find some 
brands of cement on the market varying to a degree which is inexcusable 
and which should seriously impair the reputation of the brand on the 
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