II, W. E. COOK. 
from the field on the State University Grounds. This was 
ground in the same way that the clay was. It was found 
to have no hydraulic properties. 
As each kind of cement was used with each kind of sand, 
and also with the same proportions of loam and of clay, 
there were 12 sets of curves, showing strength up to 12 
months. Arranging the diagrams in the order indicated, 
some interesting conclusions may be drawn. 
Composition ( Lehigh Dyck Lehigh Dyck Lehigh Dyck 
of Bank Bank Standard Standard Lake Lake 
briquettes. Clay Clay Clay Clay Clay Clay 
Ibs. per sq. in. 625 560 550 500 500 4.25 
Composition Lehigh Dyck Lehigh Dyck Lehigh Dyck 
of Bank Bank Standard Standard Lake Lake 
briquettes. Loam Loam Loam Loam Loam Loam 
Ibs. per sq. in. 650 550 525 450 450 400 
It will be seen that the strengths of the clay and loam 
briquettes are almost the same, and that Lehigh cement 
tests stronger than the Dyckenhoff in each combination, as 
it did in the neat briquettes. The bank sand also proved 
stronger at each combination than either the standard or 
lake sands. 
In 72 curves representing cement, sand, and clay or loam 
only 5 fell below the zero per cent., and the 15% mixture 
of clay or loam proved to be the strongest in 8 out of 12 
cases at the end of the year. It seems reasonable to con- 
clude, therefore, that clay or loam up to 15% is beneficial 
to cement mortar. However, the disadvantage of using 
a high per centage of loam or clay in mortar to be immersed, 
must be kept in mind. If the mortar is to be placed 
immediately under water, more than 8? would cause some 
trouble, as it takes longer to reach its final set. 
The writer states that he is satisfied that time and 
money spent in washing sand for Portland cement concrete 
is wasted, and that the importing of lake sand, frequently 
specified at many places, is unnecessary. The writer also 
