ON BITUMENS, &C. 187 



It is therefore very different from the fchitius, the component 

 ingredients of which were afcertained from (he following 

 analyfis. 



ANALYSIS OF THE SCHISTUS FROM ICELAND*. 



A. 250 grains, by diftillalion, yielded water, which, in the Analyfis of the 

 latter part of the procefs, became flightly acid and turbid, 1011 us ' 



= 42.50 grains. 



B. The heat was gradually increafed, until the bulb of the 

 retort was completely red hot. During the increafe of the 

 heat, a thick brown oily bitumen came over, which weighed 

 7.50 grains; it was attended with a copious production of 

 hydrogen, carbonated hydrogen, and carbonic acid, the whole 

 of which may be eftimated at 23.75 grains. 



C. The refiduum was black, like charcoal, and weighed 

 176.25 grains ; but, being expofed to a flrong red heat in a 

 crucible of platina, it burned with a faint lambent flame, and 

 was at length reduced to a pale brown earthy powder, which 

 weighed 122 grains; fo that 54.25 grains were confumed. 



D. The 122 grains were mixed with 240 of pure potafh ; 

 and, as fome particles of charcoal remained, 50 grains of nitre 

 were added, and the whole was ftrongly heated, during half 

 an hour, in a filver crucible. The mafs was then diflblved 

 in diftilled water, and, muriatic acid being added to excels, the 

 liquor was evaporated to drynefs, and was again digefted with 

 muriatic acid much diluted ; a quantity of pure filica then re- 

 mained, which, after having been expofed to a red heat, 

 weighed 98 grains. 



E. The liquor from which the filica had been feparated, was 

 evaporated nearly to drynefs, and added to boiling lixivium of 

 potafli ; after the boiling had been continued for about one 

 hour, the liquor was filtrated, and a quantity of oxide of iron 

 was collected, which amounted to 6 grains. 



F. Solution of muriate of ammonia was added to the pre- 

 ceding filtrated liquor; and, the whole being then heated, a 

 copious precipitate of alumina was obtained, which, after 

 having been made red-hot, weighed 15 grains. 



Carbonate of foda caufed the preceding liquor (after the 

 feparation of alumina) to become flightly turbid, but not any 

 precipitate could be collected. 



* The remaining fpecimens are now in the Britifh Mufeum, 

 and in the colle&ion of the Right Hon. Charles Greville. 



By 



