508 



A. C. LANE MINE WATERS AND THEIR FIELD ASSAY 



water draw inferences as to arid or other conditions of formation of cer- 

 tain beds. 



IMPORTANCE OF STUDYING CHEMICAL CHARACTER 



From what we have said, the importance of studying the chemical char- 

 acter of waters appears. I have, indeed, speculated on the possibility of 

 the difference in kinds of coal, of oil and gas, of limestone and dolomite 

 being due to variation in the chemical character of the connate water; 

 but, independent of these, we see the importance of water tests, not merely 

 because of the practically different effect upon boilers and mine pumps, 

 but because we may obtain light upon the amount, activity, and direction 

 of underground circulation. If the connate waters are but partially 

 rinsed out, the degree to which they remain and the lines of equal 

 strength must surely mark the channels of underground circulation. 

 For this purpose very many tests must be made. One careful analysis of 

 the mine water as pumped — and that or mere boiler water analyses are 

 what most mine water analyses seem to have been — is obviously of little 

 use. We must begin by making crude quantitative tests from different 

 parts of a mine — in fact, from as many points as a few drops can be col- 

 lected. We shall then, perhaps, be able to recognize the characteristic 

 types and take of these larger samples, to be more carefully studied. 



When the waters are so concentrated as are the deeper mine waters and 

 contain several thousand parts per million of solids, even a sample of 20 

 or 30 cubic centimeters (a fluid ounce) commonly permits determination 

 of nine-tenths of the constituents with an accuracy something like 1 per 

 cent. This should be enough to trace the main lines of distribution of the 

 different types of water. It is, however, important at times to get an idea 

 of the composition of even a drop or two. In such case examination of a 

 dried drop under the microscope and determination of the index of refrac- 

 tion are available methods. 



For such preliminarjr testing volumetric, nephelometric, and colori- 

 metric methods are obviously the thing, such tests as have been called^' 

 "The field assay of waters." Tests of this order were made by Davis and 

 myself in Huron county^® and by Owen in Bay county,^" and have been 

 reduced to a system and a suit case by M. 0. Leighton; but even this suit 

 case is at times too heavy, and a vest-pocket laboratory is needed. Fortu- 



'* M. O. Leighton : U. S. Geological Survey water supply paper no. 151. See also 

 various publications of tbe U. S. Department of Agriculture, Bureau of Soils, Bulletin 

 no. 31, by 0. Schreiner and G. H. Failyer, 1906. 



1' Michigan Geological Survey, vol. vii, part ii. 



^ Michigan Geological Survey, annual report for 1902. 



