114 
IOWA ACADEMY OP SCIENCE 
and subjected to the action of water, a new plasticity can be developed in it 
and it would eventually set, developing a very considerable degree of strength. 
On the basis of the tests with the Soxhlet extractor we venture the assertion 
that as over 24 per cent of the cement was removed from concrete in less than 
150 hours, 24 per cent of the original strength of a bricquette of neat cement 
can be redeveloped by perfectly natural means such as we have just suggested. 
Let us pass for a moment the chemical investigation of the nature of Port- 
land Cement to an inquiry of the nature of calcium upon which the nature of 
Portland Cement must necessarily rest. Investigations of all the calcium sub- 
stances known to mineralogy and also these silicates which contain calcium in 
any degree, we find them all subject to the attack of simple acids, hydrochloric, 
acetic, carbonic, the carbonic and acetic, almost without exception having a 
steady power over all those which hydrochloric will attack. And we further find 
that this solvency increases as the percentage of calcium increases. While no 
thorough investigation of this problem has ever been made so that there is any 
law established to say that the solvency is in direct ratio to the per cent of 
calcium, yet the practical results thus far obtained and entered into mineralogy 
literature show, without exception, solvency increasing when the per cent of 
calcium increases. This shows that calcium will readily combine with the acids, 
that it is restless and active wherever we find it. This being the case, the 
calcium will also take the acid atom away from the neutral salt that contains 
an acid the calcium has an affinity for. A step further shows us that calcium 
does come away from combination in Portland Cement in the presence of 
sodium chloride or magnesium sulphate and water. Metathesis occurs and we 
have a calcium chloride or calcium sulphate as the result. 
Some very valuable work has recently been done at the Agricultural Experi- 
ment Station of .Bozeman, Montana. Prof, E. T. Tannat, C. E. of the experi- 
ment station, and Prof. E. Burke, of chemistry, both working in connection with 
City Engineer Swearingin of Great Falls, Montana. Briefiy stated, their work 
shows that the ordinary white alkali, so common in that state, attacks and 
destroys cement concrete and probably some kinds of sandstone. The import- 
ance of this discovery is recognized when one considers the important part 
which cement plays in the construction of foundations, drains, sewers, irrigation 
work an other constructions, and the fact that nearly all of the soil of Montana 
contains more or less alkali. A bulletin soon to be issued* by the experiment 
station will contain reports of these investigations. The result of this discov- 
ery means that it is unsafe for people to use cement in the construction of 
any foundation or other structure coming in contact with the soil in the alkali 
regions of the state unless some method is devised to protect them from the 
chemical. The men interested made a thorough investigation of several of the 
large sewers and found that several of them had been completely destroyed, 
and that others were fast decaying. Some of the sewers examined had onl;^ 
been in use for a short time. This bulletin on the action of alkalis will be 
awaited with the greatest of interest. It will be very important to know 
whether the destructive action is due to the free alkali or the action of alkaline 
salts. 
I have in my hand letters from Chauvenet & Bro., leading chemical engi- 
neers, of St. Louis; also from G. B. Frankforter, dean of the School of Chemistry 
of the University of Minnesota, and Leverett Means, professor of chemistry of 
Williams College, Williamstown, Mass., dated 1906, 1907, and a large number of 
