Mr, Hatchet i *.r Obfervations on Bituminous Suljlanccu 151 



B, No. 6. 



Elaftic bitumen, the whole mafs of which refembles fine cork.-^ 

 The fpecific gravity is 0,9748. 



B, No. 7. 



The fame, but friable, and apparently patting by decompofition 

 into an ochraceous coloured powder. 



The varieties of the firft fpecies of the elaftic bitumen, or that 

 which is like the cahout-chou, evidently appear to be formed from 

 a naptha or petroleum, which, like that which produces the other 

 fimple bituminous mbftances formerly mentioned, is fufceptible of 

 various degrees of infpifiation. 



All the varieties of the firft fpecies, from No. I, to No. 15, may 

 be regarded as thus formed, for in thefe we can trace all the modi- 

 fications comprehended between petroleum and afphaltum ; with 

 this difference, that the intermediate modifications of this fpecies 

 have the remarkable property of elafticity, which is the moft com- 

 plete in the variety which occupies the middle place between pe- 

 troleum and afphaltum. 



The fecond fpecies B, or that which refembles cork, appears fo 

 different from that marked A, that it is not at firft eafy to conceive 

 how they are connected, or at leaft the difficulty muff, appear great 

 to thofe who have only feen fpecimens of each fpecies complete in 

 their refpeclive characters. But, from an attentive examination of 

 mawy fpecimens, and particularly of thofe which I have defcribed, 

 I am convinced that the varieties of the fpecies B are only modi- 

 fications of the fpecies A, produced probably by long maceration 

 in the water of the rivulet in which this fpecies is found, to the 

 effects of which we may, with fome appearance of reafon, add the 



vicifStudes 



