1869.] ROCKS CONTAINING ORGANIC SUBSTANCES. 457 



When larger quantities (40 — 80 grammes) were macerated at 

 the ordinary temperature with diluted nitric acid, well determin- 

 able quantities were obtained of phosphoric acid and chlorine, as 

 also of lime, the last even in the specimen 5 (in which, though 

 11 grammes were analyzed, no carbonic acid was found). Hence 

 one may conclude that the rock contains a little apatite. Traces 

 of manganese and copper were also observed. The silicious 

 ingredients of the rock were also a little dissolved, and it may 

 perhaps be inferred, that the traces of silica were separated before 

 testing for phosphoric acid. 



The organic ingredient may be easily obtained in a very pure 

 state by washing, when a sufl&cient quantity of the rock is 

 employed. The purest specimen that I obtained afforded after 

 combustion only 3.17 p.c. of a reddish ash, but still contained some 

 mineral fragments. The ash, of which those fragments consti- 

 tuted perhaps the principal part, showed no reaction on curcuma 

 paper. In a few centigrammes, collected after analysis, I found 

 gypsum, oxyd of iron, silica (and phosphoric acid ?) apparently 

 derived from the combustion of the organic matter. 



The carbonaceous substance thus purified forms a light powder 

 of a beautiful bluish black colour. It is but slightly hygroscopic 

 and is not easily wetted with water. When heated, it concretes 

 a little, but without melting or sensibly changing its state of 

 aggregation, and productis a .transient but brilliant flame ; the 

 remaining coal smoulders very slowly out. The specific gravity I 

 found to be 1.299; after the removal of all remaining stony 

 matter, it would probably be about 1.27. Analysis by combustion 

 gave the following results (ash and water being supposed to be 

 removed) : 



The carbonaceous substance obtained from 



No. 3. No. 2. Medium. 



Carbon 88.68 88^9^ — 88.74 



Hydrogen 5.35 5.56 — 5.46 



Azote — — 0.67 0.67 



Oxygen — — — 5.13 



100.00 



The carbonaceous substance is generally but little affected by 

 solvents. Spirit of 90 per cent, pure alcohol became yellow and 

 dissolved scarcely one per cent of a substance, probably colour- 

 less when pure, and easily soluble in alcohol ; when heated it 

 Vol. it. E No. 4. 



