Morgan and TaUmon — Occurrence of Bitumen. 373 



liberated the fetid odor previously mentioned, but left behind 

 small amounts of a very voluminous insoluble black residue, 

 largely carbonaceous, which from 1 gram of the ignited mate- 

 rial did not exceed 0*0006 gram. Since the analysis of many 

 "stinking" limestones, barites, cherts and quartz failed to 

 show the presence of carbonaceous matter, it seems safe to say 

 that the limestone composing the matrix by which the egg was 

 surrounded does not contain as much as 0*1 per cent of car- 

 bonaceous matter. Furthermore, this small amount is of a 

 pyrobituminous rather than a bituminous nature, requiring a 

 temperature of approximately 800° C. to decompose it into 

 gaseous decomposition products. 



Evidence as to Origin. 



In seeking for an adequate source of the tar present within 

 the egg the most satisfactory answer may be obtained by the 

 method of exclusion. The specimen was found in a region 

 from which very few deposits of bituminous substances have 

 been reported. It is necessary to assume that the colemanite 

 came in from outside in solution, percolating through the 

 matrix. The detection of boric acid in the limestone is, there- 

 fore, what would naturally be expected. If the very insoluble 

 tar had come in through the matrix in a similar manner, it 

 would be highly reasonable to expect to detect its presence, 

 also, in the matrix. No tar was found except in the layer 

 immediately in contact with the shell, where all evidence goes 

 to show that the movement has been in the contrary direction, 

 i. e., from within toward the exterior. In short, no evidence 

 has been discovered to indicate that the tar came in from 

 without. 



On the other hand, there is considerable evidence to indicate 

 that the tar could hardly have come in from an outside source. 

 The tar is entirely too viscous to have come in its present con- 

 dition through the solid matrix surrounding the egg. It is 

 possible that it might have passed through the matrix dis- 

 solved in a lighter solvent which has since disappeared. In 

 this case, after entering the egg, as the solvent evaporated the 

 solution must have concentrated and tended to collect in one 

 deposit on the bottom of the cavity. But there are several 

 deposits of the material within the eggshell, some being diamet- 

 rically opposite the main body of material which is assumed to 

 have collected on the floor of the cavity. Similarly, the dis- 

 tribution of the tar inside the shell, coupled with its ready 

 decomposability when heated, forbids the possibility of its 

 having entered from without in the gaseous state. Consider- 

 ing the properties of the tarry material, there seems to be no 

 reasonable possibility that it could have come in from an 



