38 The Philippine Journal of Science - i9i8 



If a cement is gauged with solutions of several chlorides, con- 

 taining the same amount of chlorine per liter, it should give the 

 same results, aside from the experimental error, as far. as the 

 chlorine ion is concerned. In the same way, if we gauge a ce- 

 ment with solutions of several salts of sodium, for example, 

 having the same amount of sodium per liter, we have a basis 

 for comparing the effect of the negative ion. Further, by using 

 a number of salts that form soluble calcium compounds and 

 a number of others that produce difficultly soluble calcium com- 

 pounds, we should be able to obtain data on the question of 

 whether or not there is any relation between the effect of 

 electrolytes and the solubility of the calcium compounds which 

 they produce. 



A stock solution of each electrolyte was first made and stand- 

 ardized. This was normal on the basis of the negative ion. 

 Various dilutions were then made as needed. Care was taken 

 to choose no electrolyte that contained the principal metallic 

 elements found in cement, such as calcium and aluminium, or 

 any that contained metals that might assume the same role, 

 such as iron and magnesium. The data on all solutions employed 

 are given in Table IV. 



Mortar briquettes were made from each cement, using water 

 and four concentrations of each of the eleven solutions men- 

 tioned ; also setting time ^ and soundness tests were made on 

 each cement with each solution. The approximate average tem- 

 perature was 30° C, and the average relative humidity was 

 about 80 per cent. All the tests were made in accordance with 

 United States Government specifications for Portland cement." 

 The normal consistency of each cement was determined with 

 the various solutions. The results are shown in Table V, VI, 

 and VII. 



° Each cement used in this investigation contains calcium sulphate. 

 Consequently when a cement is gauged with a solution of an electrolyte, the 

 observed setting time may be included the resultant of the effect of the two 

 substances. 



^'' See Circular 33, United States Bureau of Standards, Washington, Gov- 

 ernment Printing Office (1912). 



