372 Morgan and Tollman — Occurrence of Bitumen. 



To ascertain whether this tar could be extracted from all 

 sections of the matrix or was found alone in those layers 

 nearest the center, pieces of the limestone from three different 

 sections of the outer layers of the matrix, removed as far as 

 possible from the fossil itself, were powdered and extracted 

 similarly but no weighable residue was obtained from any 

 portion. This indicates that the carbonaceous material soluble 

 in chloroform is not distributed evenly throughout the matrix 

 but is confined to the layers in the immediate neighborhood of 

 the tar-filled fossil. Since the amount of tar extracted from 

 the matrix previously mentioned represents only about 0*06 

 per cent of the weight of the limestone, inasmuch as the 

 extracted material seems identical with the tar found inside 

 the egg and covering the shell, it is believed that this amount 

 was some of the same material from inside the shell which was 

 not extracted by the solvent previous to grinding. Therefore 

 it is believed that the matrix as a whole contains no carbona- 

 ceous matter of a bituminous nature. 



To ascertain whether the matrix contains appreciable amounts 

 of carbonaceous matter which will become bituminous on heat- 

 ing, about 10 grams of the limestone were heated in a hard 

 glass tube in an atmosphere of carbon dioxide. The products 

 of the ignition were passed through a freezing mixture to col- 

 lect any liquid distillate and the gas was collected over potas- 

 sium hydroxide solution. On heating beyond the limit of a 

 thermometer reading to 360° C, only 3 ccru of gas were collected. 

 On withdrawing tne thermometer and raising the temperature 

 to dull redness, 7 ccm more gas collected during a half -hour's heat- 

 ing, when the hard glass tube fused and blew out. Nothing 

 but a drop or two of water condensed in the freezing mixture. 

 Thinking that the gas which had collected might be air a taper 

 was applied, when a slight explosion ensued, showing that a 

 part only of the 10 ccm of gas was combustible. 



Assuming the combustible gas to have been entirely methane, 

 10 ccm would weigh 0*007 gram. In reality the amount of com- 

 bustible gas could not have been half this figure, since it 

 exploded on the application of a taper. Since extraction of 

 the heated limestone with boiling carbon disulphide left no 

 weighable amount of material, it is safe to say that the matrix 

 does not contain more than 0*02 or 0'03 per cent of carbona- 

 ceous matter of a pyrobituminous nature. 



On examining the limestone left in the tube it seemed to be 

 somewhat lighter in color. On being sprinkled on red litmus 

 paper moistened with water, the color changed to blue, showing 

 that the temperature had been sufficiently high to " burn " 

 some of the limestone in an atmosphere of carbon dioxide and 

 make it caustic. On being treated with acids it no longer 



