152 



The Philippine Journal of Science 



1918 



The air inlet was protected by a soda-lime bulb, so that the 

 water could be easily and quickly measured and delivered without 

 exposure to carbon dioxide. Narrow-mouthed glass-stoppered 

 bottles were substituted for the Erlenmeyers. 



To start one of the new series of experiments, it was only 

 necessary to wash out a bottle with air free from carbon dioxide, 

 place therein a pipetteful of water, and quickly add a glass cap- 

 sule of cement previously weighed. Only a trace of carbon 

 dioxide was present in the system. For each gram of cement, 

 431.75 cubic centimeters of water were present. At 30° C. 400 

 grams of water are sufficient to dissolve 0.612 gram calcium 

 hydroxide,^^ which is equivalent to 0.462 gram calcium oxide, 

 or 74.06 per cent of the total calcium oxide in the cement con^ 

 taining the most calcium oxide. As will be shown later, the 

 highest percentage of calcium going into solution in this series 

 was 40.89 per cent. 



Table IV shows the calcium in solution for each sample of 

 fine cement during fifteen days' shaking, or until each sample 

 had reached a constant value. 



Table IV. — Second series. Calcium dissolved from fine cement by shaking 

 with carbon dioxide free water." 



Total calcium (Ca) present per gram of cement . 



Calcium (Ca) dissolved per gram of cement: 



First period, 1 day 



Second period, 1 day 



Third period, 2 days 



Fourth period, 2 days 



Fifth period, 2 days 



Sixth period, 2 days 



Seventh period, 5 days 



Total, 15 days 



0.4369 



0. 1282 



0. 1432 



0. 0072 



0. 0147 



0.0073 



0.0131 



0.0034 



0.0056 



0. 0058 



0. 0013 



0. 0104 



0. 0026 



0. 0041 



0. 0000 



0. 1664 



0.1805 



0. 1519 

 0. 0091 

 0.0076 

 0.0018 

 0. 0014 

 0. 0031 

 0. 0000 



0. 1749 



Percentage of total calcium that goes into solution . 



40.49 39.58 



0. 1535 

 0.0118 

 0. 0025 

 0. 0038 

 0. 0017 

 0.0031 

 0. 0000 



0. 1759 



39.57 



* At the end of the sixth period three of the cements showed constant results. At the 

 end of the seventh period the other one was constant. The total Ca(OH)2 in solution at the 

 end of the operation was well below the saturation point, showing that the constant value 

 was not due to a saturated solution. 



The main difference between this series and the first is the 

 much greater amount of calcium going into solution during the 



" Seidel, Atherton, Solubilities of Inorganic and Organic Substances. 

 D. van Nostrand Co., New York (1907), 99. 



