346 CEMENTS, LIMES, AND PLASTERS. 



grass, etc., and still the marl sample can be preserved from intermixture 

 with these materials. 



A borer invented and manufactured by Robert G. Hunt & Co. is also 

 noted by Mr. Hale. This consists of a piece of steel about 18 feet 

 long, much the shape of the half of a long gun-barrel split longitudinally. 

 The end which first enters the marl is capped and pointed with steel 

 so that it will penetrate more easily, while the other end is provided 

 with a handle for raising the apparatus. The two vertical edges of the 

 barrel are sharpened so as to cut the marl. When the instrument has 

 been driven down to the desired depth it is turned half around, filling 

 the half cylinder with marl for its entire length, and then withdrawn. 

 This gives a perfect sample of the bed from top to bottom. 



The various devices above described will generally give satisfactory 

 results when operating in moderate depths of water and on any but 

 the most fluid marls. For these latter, as well as for sampling in deep 

 water, special devices are required, which are described by Mr. Hale 

 in the paper cited. But in examing deposits of marl to be used as 

 Portland-cement material the very deep and very fluid marls may be 

 dismissed without sampling. For under present economic conditions 

 such materials could not be profitably used in cement-manufacture. 



After the results of the borings have been plotted in such a way as to 

 give both depth of water and thickness of marl, the amount of marl 

 available can be calculated quite closely. In making these estimates it 

 will be safest to assume that each cubic yard of marl in the lake will 

 yield 900 pounds of dry marl, or sufficient to make two barrels of cement. 

 Each rotary kiln in the prepared plant will on this basis use about 50 

 to 60 cubic yards of marl per day, or about 18,000 cubic yards per year. 

 An eight-kiln plant should therefore own about 3,000,000 cubic yards 

 of marl, which would insure a twenty-year supply of raw material. 



List of references on marls. Of the following papers on marls, those 

 dealing chiefly with the origin of marl deposits are marked A] those 

 describing the deposits of certain States or areas are marked B; and 

 those discussing the technology of marls as cement materials are 

 marked C: 



A, B. Blatchley, W. S., and Ashley, G. H. The lakes of northern Indiana and 



their associated marl deposits. 25th Ann. Rep. Indiana Dept. Geology 



and Natural Resources, pp. 31-321. 1901. 

 A. Davis, C. A. A contribution to the natural history of marl. Journal of 



Geology, vol. 8, pp. 485-497. 1900. 

 A. Davis, C. A. A remarkable marl lake. Journal of Geology, vol. 8, pp. 



498-500. 1900. 



