42 KANSAS ACADEMY OF SCIENCE. 
The analyses show the soils in both plats to be well supplied with the essen- 
tial constituents, with the exception of phosphoric acid. This, while about the 
average in plat Il, seems to have become considerably depleted in the plat kept 
continuously in wheat. 
It will be interesting in this connection to note the product of grain during 
the eighteen years that the experiment continued. The following figures are as 
published in bulletin No. 71 of the Experiment Station, excepting for the last 
year, which is from press bulletin No. 1. The year of harvest and the yield in 
bushels of grain are given: 
WSS Sa he. i55 9.00 | 1887, winter-killed. 1803; i404. 11.65 
NOES is cochn wis abig hS Ree SOUR SBS ake oerk syste 30.31, |, ABD Siicn iaiapsiecien 6.05 
1883 .. iE | As okies ci aiaitin's 5) 37.00 | 1895, winter-killed. 
Bh h ie ee ee OO ECR gan, ome teats 22.00 | 1896; .....erceme 24.85 
ROD Aes seas son's ahs 13750) BRON. ec cece 30.75 | 1880.2. cu ssa 4.43 
1886, winter-killed. Cho Pea eee ae 31.30 | 1808.0 ..525 saeuee 9.77 
The total yield for the eighteen years was 342.5 bushels, an average of nine- 
teen bushels per acre. This period includes three years in which the crop was 
winter-killed, and two more in which it was partially winter-killed. The soil is 
an upland, and would be regarded as of only moderate fertility, in view of which 
the yield obtained must be regarded as quite satisfactory. It will be noticed 
that during the last third of the period the product was materially less than pre- 
viously, but whether this is due to soil exhaustion or merely to exigencies of the 
season must be left undecided. 
The analyses of soil given above were made for me by Mr. A. G. Adjemian. 
SILICA CEMENT MORTARS. 
BY W. TWEEDDALE, TOPEKA. 
Read before the Academy, at McPherson, December 29, 1899, 
Cement plaster, a product of Kansas extensively used instead of lime mortar 
for plastering the inside of buildings, has been fully described in the fifth volume 
of report of the University Geological Survey of Kansas. I desire in the same 
line to present to you, for your information, another Kansas product which gives 
promise of being even of greater value as a constituent of mortar; which, possess- 
ing hydraulic properties, combines economy in cost with adaptability to all 
classes of masonry or concrete construction, from the heaviest foundation to the 
finest statuary. In said report it is termed volcanic ash; it is found of different 
degrees of purity, in practically inexhaustible quantities in a number of places 
in Kansas; it consists of silica, nearly white in color, and under the microscope 
appears to be in thin, transparent scales, overlapping each other, instead of, as in 
the case of grains of sand, being rounded, irregular particles. 
To understand the value of silica as an ingredient of cement mortar, it will be 
of interest and tend to clearness to explain the characteristics and distinguishing 
differences, not only between lime mortar and cement mortars, but also between 
cement mortars of different kinds. These differences are both chemical and 
physical. 
Lime, as a constituent of lime mortar, is an oxide of lime manufactured from 
a carbonate of lime, as limestone, chalk, or marble, by driving off the carbonic 
acid by means of heat in especially prepared kilns. This lime, when slaked with 
