xiii, A. 4 Witt and Reyes: Solubility of Portland Cement 

 Table I. — Analyses of cements. 



[Numbers indicate percentages.] 



149 





Brand. 



I. 



II. 



III. 



IV. 





2.43 

 22.60 

 7.72 

 1.76 

 61.32 

 1.08 

 1.45 

 1.63 



2.15 

 21.40 

 7.58 

 1.70 

 62.94 

 1.37 

 1.61 

 1.14 



2.17 

 21.26 

 8.54 

 2.08 

 62.82 

 1.13 

 1.02 

 1.17 



3.24 

 20.62 

 6.62 

 2.56 

 63.50 

 1.43 

 0.82 

 1.33 



Silica (Si02) - 

















Five hundred cubic centimeters of water were placed in each 

 of four 800 cubic centimeter Erlenmeyer flasks, fitted with a 

 rubber stopper with two holes. Through one of these holes was 

 inserted a reflux condenser; the other carried a glass tube bent 

 at right angles, the end of which projected beneath the surface 

 of the water. The water was boiled for an hour or two by 

 means of a Bunsen burner, until all the dissolved gases were 

 expelled. The flame was then removed, and a current of air 

 free from carbon dioxide " was passed through the tube into the 

 liquid, until the flask and contents had assumed room tempera- 

 ture. In the meantime two grams of cement were weighed into 

 a small glass bulb. While the current of air was still passing, 

 this bulb was dropped into a flask. The two-hole stopper was 

 replaced with a solid stopper and the contents vigorously shaken 

 to prevent the cement from caking. The flask was then placed 

 in a mechanical shaker and vigorously agitated for twenty hours. 

 Of the several types of shakers available for this work, the 

 most satisfactory may be described as follows : A small platform 

 was mounted on grooved wheels, which were supported by a 

 small track. This platform was rapidly driven back and forth 

 by a crank shaft, having a stroke of about 12 centimeters. The 

 flasks were clamped in a horizontal, longitudinal position. The 

 flask was then removed and allowed to stand for twenty-four 

 hours, when the solid matter completely settled, leaving a clear 

 supernatant liquid. The stopper was partly removed, and the 

 tube was inserted in the neck of the flask, through which a 



' The air was passed through two wash bottles containing potassium 

 hydroxide solution and then through one containing barium hydroxide 

 solution. The last named acted as an indicator. If a trace of carbon 

 dioxide escaped from the first two bottles, it was caught in the third and 

 produced a turbidity. The contents of all of the bottles were then changed. 



