IOWA ACADEMY OF SCIENCE 
145 
manner, one was placed in the special apparatus and the other in the 
ordinary extractor. The per cents dissolved under the two conditions I 
will dwell upon later. 
After an extractor had run for a period, the length of which was gen- 
erally chosen at 120 hours, the howl and its contents were replaced by 
another bowl containing a fresh supply of distilled water. The dissolv- 
ing process was then continued for another period. 
As soon as a bowl was removed the analysis of its contents was begun. 
The bowl was placed in a sand bath and the water evaporated to dry- 
ness. It was then heated in an oven and cooled in a bell jar. Even 
where this method was followed, some difficulty was experienced in ob- 
taining the exact weight, as the contents of the bowl gathered moisture 
as soon as exposed to the air. After weighing, the bowl was filled with 
dilute HCl and kept on a sand bath for about three days or until the 
deposit which adhered to the glass could be rubbed loose with a “Police- 
man.” By this process the greater portion of the contents could be re- 
moved to an evaporating dish and evaporated to dryness. It generally 
happened, however, that upon drying, the bowl still showed a white 
film adhering in spots. To recover this, the bowl was filled with Am- 
monium Hydrate and again placed in the sand bath for a time. This 
second amount was likewise evaporated to dryness, then made slightly 
acid with HCl and added to the first. The bowl was weighed after 
being dried in an oven and cooled in a bell jar. The total amount re- 
moved was then treated to a regular dolomite analysis. 
The results of these analyses, together with the per cent that was dis- 
solved out each time, the total per cent dissolved from the piece, the 
length of the individual running and the total time run are all given in 
tables I, II, III and IV. 
Tables I and II are especially interesting since in them are summar- 
ized the results obtained in running the two samples of the same piece 
of concrete at different temperatures. From the results obtained it ap- 
pears that the cement is fully as soluble in the cold water as in the hot. 
We may, therefore, conclude that results obtained when the water was 
hot are as fair as though the water had been cold in every case. We pur- 
posely chose Sample No. 1 for this comparative test because it seemed 
to be much the best of any of our samples. 'That it was the best of any 
we ran is shown by results obtained from Nos. 2, 3, 4 and 5. All of 
these latter samples were either partially or wholly disintegregated at 
the end of the last running, yet, while No. 1 was run in both hot and 
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