144 
IOWA ACADEMY OP SCIENCE 
was repaired and it was expected that the trouble would cease. Later the 
writer visited the city, inspected a number of manholes and found that 
'considerable of the cement mortar in the bottom of manholes is in various 
stages of decay, some crumbles readily and is easily removed. This con- 
dition should it prevail in the mortar joints of pipe lines, offers an out- 
let in the ground water in the gravel beds which supply the city water. 
The matter has gone into the courts, meanwhile the people’s health is at 
the mercy of escaping sewage and poisoned household water. 
A continuation of the studies suggested two years ago called for a 
definite inquiry as to the exact power of pure distilled water to act upon 
the substance of portland cement. Mr. Orin L. G. Kipp, now assistant 
professor at Ames, carried out tests in the school year of 1908-9. 
Samples were taken from a number of twelve-inch concrete pipe. These 
were chosen to study two conditions of pipe. Some of these pipe rang 
clear and strong under the testing hammer and when submitted to the 
crushing test carried a load of far more than the required strength. The 
broken section showed dense, close .concrete with plenty of cement. 
These pipe carried a load equal to 77 % of first class vitrified pipe tested 
on the same machine and the same method of contact. These samples 
were chosen as being representative of the better quality of concrete now 
Ibeing manufactured in the state of Iowa. 
In preparing a sample for testing, a piece about an inch square was 
broken off and all the loose pebbles or sand brushed from it. The sample 
was then heated in an oven at about one hundred degrees C. until constant 
weight was obtained. After weighing the sample, it was placed in a 
Gooch crucible which was lined with a filter cup, and this was suspended 
at the lower end of the inverted condens'er projecting into a Sohxlet ex- 
tractor. The bowl of this extractor was filled about two-thirds full of 
distilled water, and the flame lighted below it. 
As this method of producing a flow of water over the concrete might 
be subject to criticism on acount of the fact that the water flowing over 
the concrete was hot, a piece of special apparatus was constructed which 
allowed the water to flow over the concrete at normal temperature. 
/This special apparatus is shown in the flgure below, a slight study of 
which will make its working clear. The steam passes from the bowl of 
the tube to the right and into the condenser from which the cold water 
flows over the piece of concrete, ‘‘A,” and then flows back to the bowl 
at intervals as the receptacle below fills and syphons over. 
In order that a fair comparison of the action of cold and hot water 
might be obtained, two samples as nearly alike as possible were taken 
from the same piece of concrete, and after being prepared in the usual 
