150 



The Philippine Journal of Science 



current of air free from carbon dioxide was passed. A pipette 

 was then inserted, and portions were withdrawn for analyses. 

 The solids in the bottom of each flask consisted of two layers. 

 The upper was white and flocculent, consisting partly of alum- 

 inium hydroxide. The lower was much larger and evidently con- 

 sisted partly of cement which had not been decomposed by the 

 action of the water. Analysis of the supernatant liquid showed 

 it contained in solution considerable calcium, a trace of iron and 

 aluminium, and no silica. The shaking was repeated for another 

 period to see if any more calcium went into solution. Analysis 

 showed there was an appreciable increase. This was repeated 

 until the flasks had been shaken for a total of four hundred 

 twenty-six hours. Numbers II and IV had become constant, and 

 number I practically so, but number III still showed a gain. The 

 lower layer of solid in the flask had almost entirely disappeared, 

 only a few particles remaining. During the experiment it was 

 necessary to add more water from time to time to keep the 

 solution from reaching saturation. It was decided to stop the 

 work at this point and start a new series after making a number 

 of changes that the work had suggested. The results of the 

 first series of tests are given in Table II. It will be noted that 

 from 35 to 38 per cent of the total calcium of each cement went 

 into solution. 



Table II. — First series. Calcium dissolved from original cements during 

 various periods of shaking with carbon dioxide free water. 



[Numbers indicate weight of calcium, in grams, per gram of cement.] 



Total calcium (Ca) in cement . 



Calcium (Ca) dissolved during each period: 



First period, 20 hours 



Second period, 16 hours 



Third period, 20 hours... 



Fourth period, 40 hours 



Fifth period, 55 hours 



Sixth period, 48 hours 



Seventh period, 22 hours - ■ 



Eighth period, 41 hours .- 



Ninth period, 54 hours 



Tenth period. 45 hours 



Eleventh period, 65 hours 



Total, 426 hours 



0. 0665 

 0.0071 

 0. 0129 

 0.0086 

 0.0168 

 0. 0255 

 0. 0071 

 0. 0106 

 0.0032 

 0. 0041 

 0.0020 

 0.1644 



0.4490 0.4539 



0. 0808 

 0.0125 

 0. 0245 

 0. 0114 

 0.0130 

 0. 0208 

 0. 0038 

 0. 0066 

 0.0007 

 0.0000 



0. 0843 

 0. 0089 

 0. 0172 

 0. 0115 

 0.0114 

 0.0138 

 0.0063 

 0.0052 

 0.0010 

 0.0029 

 0.0104 



0.0681 

 0.0259 



« 0.0288 

 0. 0129 

 0.0184 

 0.0053 

 0.0000 



0. 1729 0. 1594 



Total calcium dissolved (percent) 37.51 



• This value represents the amount dissolved during both third and fourth periods. 



