May 12,1923 
Effect of Decomposition on Concrete Tile 
477 
Two outstanding facts were indicated. The first was a greater solu¬ 
bility of the tile in distilled water than in either the carbonated or bog 
water. The second was that though pieces of tile had been agitated 
for 3 days in water from the margin of the marsh, the quantity of 
lime actually in the water was less than in the beginning. 
This result showed that the original premises were not well founded. 
They were either incorrect or something had been omitted from them. 
Within the power of the test to show it, carbonic acid was not causing 
the destruction of the tile; neither was the marsh water, apparently. 
TESTS FOR alkali 
There appeared to be no explanation for the results given in the Table I 
until it was suggested that perhaps the marsh waters did not actually 
contain free carbonic acid and that the tile, even after a lengthy curing, 
might contain free alkali. To test this, a quantity of tile was powdered 
and to it a small amount of distilled water was added which was immedi¬ 
ately poured off and filtered. It gave a powerful reaction with phenol- 
phthalein, showing that the tile was not only alkaline but that a con¬ 
siderable quantity was soluble in water. A quantity of the powdered 
tile was boiled in distilled water, filtered, and while still hot 100 cc. of 
the filtrate measured. This gave 3.582 gm. of residue on evaporation, 
a surprising percentage considering the age of the tile. 
The marginal and bog water was then tested on the assumption that 
they contained free organic acids. Methyl orange showed that they did 
not. They were then titrated with standard sulphuric acid solution, 
■jij normal strength, using methyl orange as an indicator. The test 
disclosed strong alkaline reactions, showing unneutralized alkalies of 
the strength indicated in Table II. 
Table II .—Showing the amount oj normal acid solution required to neutralize 
the free alkali in marginal and hog water and its equivalent in CaO per liter of water 
Equivalents. 
Marginal water. 
Bog water. 
Cubic centimeters of one-fourteenth normal solution used.., 
CaO equivalent per liter, gm. 
IS- 30 
• 1530 
14. 80 
. 1480 
The contradictory results obtained were now explained on the basis 
of the precipitation of calcium carbonate formed from the more soluble 
calcium bicarbonate by the free alkali of the tile taking away one-half 
of the carbonate radicle. 
However, this did not make the explanation of the disintegration of 
' the tile any clearer; instead, it became still more obscure. 
COMPARISON OF OLD AND NEW TILE 
The results of the tests using the new tile being apparently so different 
from what had actually happened in nature, it became necessary to 
compare the old and new tile in order to determine whether or not the 
new tile differed in any material degree from that which originally went 
into the drains. 
