240 



HENRY W. NICHOLS 



the water evaporate until only ^ liter remains. One liter of 

 water at 54 F. will hold in solution approximately 1100 grams 

 of calcium nitrate 1 and (disregarding the influence of the cal- 

 cium nitrate) only 0.88 gram of calcium carbonate. 2 When 

 reduced to ^ liter by evaporation it will hold only 825 grams 

 of calcium nitrate and 0.66 gram of calcium carbonate. If 

 the solution be now removed, there remains a precipitate of 

 275 grams of calcium nitrate and only 0.22 gram of calcium 

 carbonate. This applies to all cases of soluble with slightly 

 soluble salts except where chemical actions intervene, as in the 

 case of phosphates. In one specimen from Dixon's Cave the 

 analysis of the cave earth, recalculated below, shows a very 

 large excess of carbonates. In this case the amount of soluble 

 salts is very minute (0.5655 per cent.), and we probably have 

 the beginning of a stalagmite deposit forming in the nitrates. 

 Over 90 per cent, are bases, with only 5^ per cent, of sulphuric 

 acid. There is no analysis of dropping waters for comparison 

 in this case, however. 



SALTS LEACHED FROM CAVE EARTH AND OVERLYING BAT GUANO, 



DIXON'S CAVE. 



As the overlying bat guano in this case yields up to water 

 salts of which over 57 per cent, are nitric acid, it is difficult to 

 understand how a water carrying the traces of nitrates from the 

 surface of the earth could penetrate this guano to the underlying 

 cave soil without taking along much more nitric acid from the 

 bat guano than the almost infinitesimal quantities it brings from 

 the surface. In this case the soluble part of the deposit is 

 undoubtedly a mixture of the matter in the drip and the matter 

 leached from the bat guano, and there is a bare possibility that 



1 Ostwald : Outlines of Theoretical Chemistry, p. 150. 



2 Roscoe and Schorlemmer : Treatise on Chemistry, Vol. II, Ft. I, p. 209. 



