146 STEVENSON— FORMATION OF COAL BEDS. [April is. 



is intense. Klement^^^ found so little in the almost ink-black waters 

 of Willebroeck that the material could not be investigated thor- 

 oughly. He observes that the brown waters of Gouda become de- 

 colorized very quickly in presence of pulverized calcite. 



Humic and ulmic acids are certainly precipitated by lime ; but one 

 may not be regarded as hypercritical if he suggest that this can 

 have very little to do with the supposed precipitation of ulmic 

 matters in the ponds or stagnant waters of swamps. The deposit 

 was laid down in water with undisturbed surface ; that would be a 

 stagnant pool, which could be filled only by rainfall or by seepage 

 through the peat. But the seepage water, however rich it might be 

 in lime at its entrance, would lose all while percolating through the 

 peat, as organic acids would take it up; if, in course of time, an 

 excess should exist and should reach the pool, the lime would find 

 no organic acids there, as the bog itself would contain only the in- 

 soluble calcium compounds which could not be leached out in ap- 

 preciable quantity. The condition would be the same, if the pond 

 were fed by a stream meandering sluggishly through the swamp — 

 no other would be possible under the supposed conditions. If the 

 precipitation were a constant process and due to presence of lime, 

 the precipitate should present abundant evidence, for there is no 

 reason to suppose that the lime would be removed at any later time ; 

 the precipitation was not merely constant, but also so rapid that a 

 thick deposit of boghead might accumulate in a single season. 

 Everything, under such conditions, would be sealed up quickly. But 

 analyses give no support to this conception of the origin, for lime 

 is an unimportant constituent of bogheads. Liversidge^*'* analyzed 

 Kerosene shale from Greta and from Joadja creek in New South 

 Wales. That from Greta contains about 28 per cent, of fixed carbon 

 and nearly 16 per cent, of ash; but of the latter only 1.438 per cent, 

 is lime. The mineral from Joadja creek has almost 16 per cent, of 

 fixed carbon and 9 per cent, of ash ; but of the latter only 0.3 per 



^*^ C. Klement, " Les puits artesiens de Willebroeck," Bull. Soc. Beige de 

 Geol, Vol. III., 1889, Mem. pp. 259-262. 



^**A. Liversidge, ''Descriptions of the Minerals of New South Wales," 

 Dept. of Mines, Sydney, 1882, pp. 162-164. 



