in the Distillation oflVood, &c. 207 



various degrees of solubility in alcohol. That which is least 

 fusible in t!ie fire, is, in both cases, tiie least soluble in alcohol. 

 And by this consideration, the jarring accounts which have been 

 given of the solubility of asphaitum in alcohol maybe reconciled; 

 and it will be seen in the se([uel, that the history of this substance 

 illustrates, in every respect, the true nature of the several varieties 

 of the bitumens, substances whose nuitual relations, and the 

 causes of whose chemical diversity, have hitherto not been under- 

 stood. 



If a perfectly soluble specimen be dissolved in alcohol, it Is 

 obtained unchanged by evaporating the spirit. In any other 

 case, the matter which the alcohol has taken up is precisely si- 

 milar to the pitch in its first state, and the residuum resembles 

 that which is the result of fusion when it refuses longer to melt. 

 Alcohol therefore separates the pure pitch from that which by a 

 process of decomposition has been nearly carbonized. Ether 

 acts upon this substance as readilv and in the same manner as 

 alcohol does. In lixivium of pure potash it is more completely 

 soluble than in alcohol, and forms with it an intensely brown so- 

 lution, which is diffusible in water without change, and which, on 

 the addition of an acid, deposits the matter in a powderv form 

 and apparently unchanged. It is also soluble in water of am- 

 monia with similar appearances. It is scarcely soluble in the 

 pale oil of turpentine, but more readily in the darker. It is 

 slightly soluble in the fat oils, in tallow and in wax, but is con- 

 siderably more soluble in drying oil. In all these cases its so- 

 lubility varies, from the same causes as those which affect its 

 solubility ni alcohol. Naphtha, whether pale or l)rown, has no 

 action on it when cold, and takes up but a very minute propor- 

 tion even with the assistance of heat. It fuses into an uniform 

 mass with sulphur, with resin, and with asphaitum. 



Acetic acid, which dissolves so many of the compoimd inflam- 

 mables, effects a complete solution of it and in large proportion, 

 and this coaipound is precisely similar to the empyreumatic acid 

 as it proceeds from the iron retorts in which the charcoal is di- 

 stilled It would be desirable, in an oeconomical point of view, 

 to discover a method of freeing the acid from the pitch. After 

 many trials, Ijy combining the foul acid with various bases and 

 again separating it, it was always foiuid to retain the overpower- 

 ing smell of wood tar. If the acid is combined with the pitch 

 at a high temperature, a large proportion of it separates in the 

 form of tar on cooling. Muriatic acid, after long boiling on the 

 pitch, became i)rown, and dissolved a little of it. 



By (li:;vstion with sulphuric acid it was dissolved, forming a 

 brown oily-looking fluid, sulphureous acid being at the same time 

 disengaged. By dilution with water, a smell resembling pepper- 

 mint 



