1913-] STEVENSON— FORMATION OF COAL BEDS. 147 



cent, is lime: no relation exists between the quantity of lime and that 

 of fixed carbon or volatile. If one take the Joadja shale as contain- 

 ing only lo per cent, of fundamental brown material, the condition 

 remains, as the lime is but 0.027 per cent, of the whole, clearly 

 insufficient for precipitation of the organic acids. 



The supply of organic acids must have been very great in order 

 that constant precipitation might be maintained, especially such 

 abundant precipitation as to give several inches of fundamental 

 jelly in the course of a single season — the water being stagnant. 

 Everywhere, the brown waters, even when almost black, contain 

 very little organic matter in solution, one part in 20,000 sufficing 

 to give marked coloration and an acid reaction. The coffee-brown 

 or greenish black waters of South America, according to Humboldt, 

 are preferred to all others for drinking, being limpid and of agree- 

 able flavor. Coville^*^ has stated that water from the "juniper 

 area" of the Dismal Swamp, with the color of tea, was the favorite 

 source of supply for vessels departing on long voyages. This is a 

 typical locality in the heart of the swamp; the water is acid in re- 

 action and the flora is of the acid-resisting type, consisting of 

 Chamoocyparis, alders and heathers. There seems to be no reason 

 for supposing that, during Carboniferous times, the stagnant waters 

 of swamps approached saturation with organic acids. 



The suggestion that the " bitumen " is of extraneous origin, that 

 it intervened fully formed, that it may have been in the water, is 

 sufficiently perplexing. Bertrand finds no evidence that it was de- 

 rived from the decomposing mass. It fills shrinkage cracks in the 

 fundamental matter and it seems to have penetrated some tissues 

 more readily than others — a condition which, for Bertrand, explains 

 some diiTerences in coals ; glance, composed of barks and cuticles, 

 absorbed much, but tissues in matt absorbed little. The algae-like 

 bodies had notable capacity for absorbing this bitumen. Renault^^" 

 has expressed an objection, which, no doubt, presented itself to 



"5 p V. Coville, " The Recent Excursion into the Dismal Swamp," Science, 

 N. S., Vol. XXXVIII., 191 1, pp. 871, 872. 



""B. Renault, " fitudes sur le terrain houiller de Commentry ; Flore fossile," 

 Livr. 2, 1890, pp. 687, 688, 701, 702. 



