HISTORY OF PITCOAL. l67 



A inixtLire of nitre and coak burns with the same diffi- and mixed 

 jcalty as mixtures of nitre and charcoal of blood, white <>f bums difficult- 

 egg, indigo, &c. ^Y 

 ' 7. There are few kinds of wood, that do not leave more Coal leaves 

 ashes than pitcoal. Coal therefore Is not clay impregnated ^J'^^f ^.^^1?^? 

 with bitumen, ais some naturalists have thought. fore not day 



I have not yet found any oxide of manganese in animal "y,'^^^^^^^^^^ '^^" 

 charcoal; and I have sought it equally in vain in the five j^^ ^,^.j^ ^^ 

 kinds of coal mentioned above, manganese. 



8. Vegetable ashes contain a great deal of carbonate of Ashes ofvege- 

 lime, beside magnesia, alumine, and silex. Those of the f^^^m^holrof 

 five coals I examined afforded me t)nly a great deal of silex, coaL 

 a little magnesia, alumine, and sulphate of lime, but very 

 little carbonate; and in particular not an atom of those salts, 

 jyhich are habitually contained in our vegetable ashes;' no 

 phosphate, no muriate of soda, though the mud of these bi- 

 tumens is supposed to have been formed with sea-water. 



10. All the soft or liquid parts of animals contain sulphur. Contains tul- 

 They cannot be dissolved in potash, without having the so- " 

 lution loaded with :t. Wool cannot be dipped in a bath of 

 litharge and lime without being blnckened, in consequence 

 of the sulphuret of lead that adheres to it. 



If no pitcoal be absolutely free from pyrites, is it not be- Nonefreefitom 

 cause Ihe sulphur and iron, those two habitual elements of P>"^^^"* 

 animal matters, have withdrawn from the organic substance 

 converted into bitumen, to form a separate combination? 



I content myself with bringing together these facts, and 

 refrain from dt ducing any consequences from them, as they 

 require to be compared with a greater number of coals, that 

 it may be known whether they be as general as I suppose. 

 But we now come to other properties, which sepa- ate still Farther differ 

 more the analogies supposed to exist between pitcoal and ve- *^"'^^^* 

 getables. ^ 



If, for exaiTiple, the carbonaceous principle be an ele- Charcoal fee- 

 pient of their composition, in the same manner, and in the !^' ^^nibine 

 same sense, as it is in our vegeta'^es and animals, we shall 

 chow, that it is very feebly combined however, verj- weakly 

 enchained at least by the hidrogen, nitrogen, and oxigen: I 

 could almost veniure to say independant of them, since it 

 may be ex.tracted from pitcoal by means, that certainly would 



never 



