122 ANNUAL REPORT. 
of a slurry, lime is added in the shape of precipitated calcium carbonate 
and thoroughly stirred with the clay. This mass is now dried down and 
rubbed through a 40 mesh sieve, mixed thoroughly on a sheet of glazed - 
paper by means of spatula and burned in a furnace. A weighed amount 
of the ignited mixture is treated with hot hydrochloric acid for five hours, 
filtered and washed, and the residue is digested with a 10 per cent. solution 
of sodium carbonate with heating, until no more flocculent silica is 
observed on testing with ammonium chloride. 
The Lunge and Schochor method and that of the Ohio Geological 
Survey differ in the following respects: 
1. Ihe above named investigators restrict their method to marls, 
while the Survey extends it to the testing of all clays. 
2. The former work with the natural materials, having varying 
percentages of lime, while the latter maintains a constant amount of lime 
by adding the lime lacking, in the form of pure calcium carbonate and 
also having the lime present in excess. 
3. Lunge and Schochor ignite the materials in the shape of lumps 
taken from the deposit; the Survey reduces them so that the soft portion 
will pass through a 40 mesh sieve with the aid of water and accomplishing 
the mixture of clay and lime when the former is in the condition of a 
slurry. 
Experimental ,Work in Demonstration of the Value of the Process.— 
Having thus outlined the method of working, there now remains to 
prove that it really gives expression to a co-efficient which is consistent 
with actual results in the manufacture of cement. For this purpose it was 
decided to bring the method as nearly possible to uniform conditions of 
operation and to agree upon a method of mixing, burning and analysis. 
The description of the work done naturally falls under the following 
headings: 
tr. Sampling and preparation. 
2,  Wilorarayer, 
3. Burning. 
Sampling and Preparation.—The clays arrived at the laboratory of 
the Ohio State University Ceramic Department in sacks, in the shape in 
which they were sent by the field collector. These clays, according to 
their nature, were treated in different ways. Clays of the soft, alluvial 
type, after being put through an 8 mesh sieve and repeatedly quartered 
according to the quantity on hand, were dried at 100° C., and about 500 g. 
was reserved for the analysis, being run, as far as possible, through a 
40 mesh sieve and thoroughly mixed; the coarser portion, of course, being 
added to the finer. When the material was a hard shale, it was necessary 
to crush it and pass it through an 8 mesh sieve. A quantity of the re- 
duced shale was then heated at 100° C. till perfectly dry and then allowed 
