THE PHILIPPINE 



Journal of Science 



Vol. XIII 



A. Chemical and Geological Sciences 

 AND THE Industries 



JULY, 1918 



No. 4 



THE SOLUBILITY OF PORTLAND CEMENT AND ITS RELATION 

 TO THEORIES OF HYDRATION ^ 



By J. C. Witt and F. D. Reyes 



(From the Laboratory of General, Inorganic, and Physical Chemistry, 

 Bureau of Science, Manila, P. I.) 



ONE TEXT FIGURE 



In connection with some previous work in this laboratory,- 

 occasion arose to treat a few grams of cement with a solution 

 of sodium sulphide and then to filter, wash, and examine the 

 filtrate. It was found impossible to wash the residue free from 

 soluble calcium compounds, for the wash water invariably showed 

 a test for that element. Moreover only a portion of the calcium 

 compounds dissolved came through the filter, because calcium 

 carbonate was formed from contact with the air. The same 

 behavior was noted when water was substituted for the sulphide 

 solution. It was found that many times the original quantity of 

 water could be added without resulting in a residue free from 

 soluble calcium compounds. This suggested an investigation to 

 determine just what constituents of cement will go into solution 

 and the proportion of the total amount of each present in the 

 sample. A review of the literature revealed that, while a num- 

 ber of writers mentioned the solubility of constituents in water, 

 there were few reliable quantitative data available,^ 



It is common experience that water in which cement test pieces 

 are stored soon contains substances in solution. It becomes 

 soapy to the touch and has an alkaline reaction, and a qualitative 

 test will reveal the presence of the calcium ion. That calcium 

 hydroxide is among the products of the hydration of cement 



' Received for publication April 10, 1918. 

 'Witt, J. C, This Journal, Sec. A (1916), 11, 273. 



'Compare, however, Winkler, A., Journ. j»'akt. Chevi. (1856), 67, 444. 

 156254 147 



