138 ANNUAL REPORT 
By practice the analyst is able to discriminate between the clay matter and organic 
matter in the flask during the period of boiling with the acid solution and after titrat- 
ting back with the alkali solution, and the per cent. of clay can be judged with sufficient 
accuracy aiter the percentage of CaCO, has been determined. In doubtful cases where 
the marl shows unusual irregularity in CaCO,, the contents of the flask may be thrown 
on the filter and the clay matter quickly determined by ignition. This, however, is 
seldom found necessary. 
METHOD No. 3. 
From each of several samples taken from different parts of the tank marl, take a 
small sample, say 20 cc., measured in a wide tube. Introduce into a dry 6-inch porcelain 
mortar, no water being used in transferring from the tube to the mortar. Grind the 
marl to an impalpable condition when the mass should be absolutely homogeneous. 
From this take for analysis 3.37 ec. (=2> 1,685 cc.) this being a sufficient quantity when 
properly manipulated and requiring a convenient quantity of 4nHCl for analysis. This 
can best be accomplished by the use of a pipette constructed according to accompanying 
cut. The pipette should be carefully dried before filling with marl and the marl all 
carefully removed with a jet of water. 4nHCl and $nKOH solutions standardized as in 
method No. 1 are employed for analysis, 50 cc. of the HCl solution being used for a de- 
termination. By the use of a table expressing the value of any number of ce. of HCl 
solution (the number of cc. liable to be used being determined by trial) in terms of 
milligrams of CaCO,, the number of pounds of CaCO, is read direct. 
Example.—lIf each ce. HCl is found to equal 2.435 per cent. CaCO, in 1 gram=24.35 
mgms. CaCO, and we find that 3.37 cc. marl requires 45 cc. HCl, then 24.3545= 
1095.71 mg. ; 
1095.71+2—=547.8 pounds CaCO, per cu. yd. of marl. The amount of clay to be 
added is figured by the aid of the formula employed in method No. 1. 
A—(BXC) 
ii see pa ESN, 
D 
B may be determined on an average sample as in method No. 2, or in ease of irreg- 
ularity of marl the contents of the flask are thrown on the filter, ignited and weighed. 
We have thus the pounds of CaCO, and of clay matter per cu. yd. and proceed with the 
calculation of clay matter required as in method No. 1, though not always so accurately 
as method No. 1 and 2. This last method is especially advantageous because of 
the rapidity of manipulation, 20 minutes being sufficient for analysis and calculation 
of results. When the marl is sufficiently uniform and the plant is so arranged as to 
~ admit of the proper correction when necessary, remarkable uniformity may be obtained 
with a minimum of time and labor. 
The above methods have all been found to give excellent satisfaction in cement 
practice, having been used according to the condition to which each was best suited in 
various cement plants in the United States and Canada. 
Fisher’s Method.—The following working method is used by Mr. 
Fred Fisher, chemist of the Newaygo Portland Cement Company. In 
employing this method Mr. Fisher has succeeded in completing, without 
help, eight analyses in an eleven hour shift, besides doing other routine 
work, but the ordinary procedure is to make seven exact analyses of 
slurry in 24 hours, employing, of course, a night assistant. 
PREPARATION OF THE SAMPLE. 
About a quart of the wet mixture or slurry, taken from a well-agitated tank, is 
brought to the laboratory. It is passed through a sausage grinder. This breaks up 
