208 On certain Products oltained 



mint was produced, as happens in a similar case with camphor, 

 and the pitch was thrown down. The action of the red nitrous 

 acid on it is violent ; the acid is decomposed with great ebullition, 

 ■ and a portion of the pitch is converted into coal. In diluted 

 nitric acid it dissolves, and produces an uniform brown fluid. On 

 continuing to apply nitrous acid according to the process of Mr. 

 Hatchett, solutions similar to those which he has described as 

 having been obtained from the resins and bitumens, are pro- 

 duced. 



I exposed a quantity of the pitch to a careful distillation 

 through water. y\s might be expected from what I described 

 before in the distillation of the tar, this procc&s gave results 

 nearly similar to the former. The oily matter ditfered in being 

 of a brown colour and in having a greater specific gravity, and 

 much less acid was produced ; the residuum was charcoal. The 

 whole process of distillation appears, therefore, to be a decom- 

 position by which the pitchy substance is converted into oil, 

 acetic acid, ammonia, and charcoal. 



I proceeded next to examine the oil. It has a violently pungent 

 taste and smell. It is scarcely heavier than water; so that it 

 sinks in that fluid with difficulty, leaving generally some drops 

 on the surface. It is perfectly soluble in alcohol, in ether, in 

 caustic alkali, in olive oil, and in linseed oil. It will unite nei- 

 ther to naphtha, nor to the recent essential oils, but is soluble 

 in the old ones. From these properties, it belongs to the class 

 of the essential oils, but exhibits at the same time other qualities 

 by which it is distinguished from the whole of them. 



Having thus examined the most remarkable chemical proper- 

 ties of this substance, it will not be irrelevant to point out its 

 differences from and its analogies with those substances which it 

 most resembles, namely resin and the bitumens, llesin, as is 

 well known, is eminently soluble in all the substances in which 

 this is dissolved, and also in those with which this refuses to 

 unite, even naphtha. But the general analogy between essential 

 oil, turpentine, and resin, is so close to that of the three sub- 

 stances which I have described, that it will not perhaps be su- 

 perfluous here to make some remarks on the nature of common 

 resin and the substances connected with it, pitch, tar, turpen- 

 tine, and essential oil, as their history will also illustrate that of 

 the substance I am describing, and as it appears, like that of 

 the bitumens, to have been somewhat mistaken. 



If turpentine, as it flows from the fir in a liquid state, be ex- 

 posed for a considerable time to the action of the atmosphere, it 

 becomes brittle, and is converted into resin, in consequence, as 

 it is supposed, of the absorption of oxygen. If the same turpen- 

 tine be exposed to the action of the fire, a colourless volatile 



oil 



