NITRA TES IN CA VE EARTHS 239 



From this table it is evident that solids from the drip water 

 contain practically twice as much lime as those from the cave 

 earth and much less sulphates and chlorides. Exact calculations 

 for the saturation of bases by alkalies cannot be made without 

 knowing the ratio of soda to potash. An inspection of similar 

 determinations for many Kentucky soils shows for similar situa- 

 tions a ratio of potash to soda of 1:4. Assuming this ratio, 

 then, in the case of the drip water, after all the acids are satu- 

 rated there is a large excess of lime left. This holds true both 

 for the salts given in the above table and for the full analysis as 

 given by Mr. Hess. This lime is held as carbonate and would 

 be deposited as calcite upon evaporation. But in the salts 

 extracted from the cave earths, as before noted, we find that the 

 acids nearly saturate the bases and there is little lime left as 

 carbonate. While the quantities will change as we assume more 

 or less soda in the mixed alkalies, yet the proportions do not 

 vary to any important degree, and in any conceivable case there 

 is a very large excess of calcite in the drip water unaccounted 

 for in the cave earth. In short, the drip in Mammoth Cave 

 carries chiefly carbonates, while the cave earths carry chiefly 

 sulphates. For the drip water to deposit any nitrate it is neces- 

 sary that it should evaporate practically to dryness and deposit 

 essentially all of its lime and other salts. For every 8 parts of 

 nitric acid, 42 parts of lime will be deposited, and thus the 

 deposit would take the form of stalagmite enclosing the clay or 

 sand, a form of deposit actually found in places but not forming 

 any portion of the cave earth. 



The removal of nitrates from guano to cave earth is different. 

 The drip becomes saturated with salts while passing through the 

 guano, deposits only part of its burden in the underlying cave 

 earth, and drains off with the remainder. The deposits thus 

 formed will be composed chiefly of the more soluble instead of 

 the less soluble salts, and no stalagmite will form. This may be 

 made more evident by assuming an ideal case. Take 1 liter of 

 water saturated with calcium nitrate, calcium carbonate, and 

 carbonic acid at 54 F. Keeping the temperature constant, let 



