248 



CEMENTS, LIMES, AND PLASTERS. 



Packing weights. In packing natural cements several different 

 standards of weight are in existence in various localities. In the Rosen- 

 dale, Howe's Cave, and Akron districts the standard barrel weighs 

 about 320 Ibs. gross or 300 Ibs. net. In the Lehigh district of Penn- 

 sylvania the gross and net weights are usually 300 and 280 Ibs. respec- 

 tively. In the Louisville, Utica, Milwaukee, Fort Scott, and other 

 western districts the standard is a barrel weighing about 285 Ibs. gross 

 or 265 Ibs. net. The recent specifications of the American Society for 

 Testing Materials require packing in bags of 94 Ibs., three bags to a 

 barrel. 



Exceptions to these general rules occur. The Howard cement of 

 Georgia is naturally so low in specific gravity that an eastern natural- 

 cement barrel will contain only about 240 Ibs. of Howard cement. 

 The Pembina cement of North Dakota is, on the other hand, packed at 

 the regular Portland weight of 380 Ibs. net per barrel. 



Costs of Manufacture. 



The items which go to make up the total costs of natural-cement 

 manufacture are (a) cost of quarrying or mining the rock, (6) cost of 

 labor at kilns and mill, (c) cost of fuel for kilns and power, (d) interest, 

 etc., on plant. Many of these points have been touched on in the earlier 

 portions of this and the preceding chapter, and will only be summarized 

 briefly below. 



Cost of raw material. The cost of excavating 1 he raw material has 

 been discussed in a preceding chapter (pages 219-221). In the follow- 

 ing estimates the figures there given will be taken as a basis for cal- 

 culation. It was stated that the cost of raw material, delivered at the 

 kiln, might range from 4 to 13 cents per barrel of finished cement. 

 For our present purposes this range in cost can be decreased some- 

 what, for at most plants the minimum and maximum limits may be 

 taken as 5 and 10 cents respectively. 



Labor costs. In estimating labor costs it may be accepted for 

 the majority of natural-cement plants that the output will vary between 

 5 and 10 barrels per day per man employed, counting the men in the 

 mine or quarry as well as those in the mill. As the cost of quarry 

 labor in the present calculation has been already charged against the 

 cost of raw material, the mill force alone should be considered here. 

 Examination of a number of plants proves that the output varies 

 between 12 and 22 barrels per day per man, counting all men employed 

 around the mill and kilns, but excluding quarrymen, miners, and 

 teamsters engaged in hauling rock to the mill. 



