obtained in the distillation of Wood^ 'zffc. 3 



If the operation be pushed by increasing the heat of the retort to 

 redness, there remains at length only a mass of spungy charcoal, 

 and the substance is totally converted into the following new com- 

 pounds, namely, the residuary charcoal, the oily matter, and the 

 matter held in solution in the water of the apparatus. This latter 

 proves to consist of a large portion of acetic acid, with which is 

 combined a very little ammonia. 



There is no inflammable gas given out in this process unless the 

 heat be carelessly managed. If the vapour of the oily matter as it 

 arises be exposed to the sides of the retort elevated to a high tem- 

 perature, it is decomposed, and instead of oil there are thus obtained 

 by a violent distillation in a naked fire, scarcely any products but 

 acetic acid and an inflammable gas. This fact is analogous to 

 those occurring in the ordinary process for decomposing such in- 

 flammable bodies as can be made to put on the gasseous state — and we 

 ought, in fact, to consider every process of this kind, where a rapid 

 distillation with a hot fire is used, as a succession of decompositions; 

 the matter first produced being afterwards exposed to another pro- 

 cess of destruction. It is not therefore perhaps very correct lan- 

 guage, to say that vegetables yield a great quantity of inflammable 

 gas on distillation with a naked fire; this is the produce of a second 

 distillation v/hich by the common mode of operating is confounded 

 with the first. As this reasoning applies equally to all other similar 

 processes, it would be desirable to use a more accurate mode of des- 

 cribing this common operation by which we might in some import- 

 ant instances be led to a more correct practice. Thus, for example, 

 in the common mode of distilling coal to produce the inflammable 

 gasses, this double operation is carried on at once by the application 

 of the petroleum and naphtha at first produced to the heated iron 

 of the retort. It is in consequence of this imperfect mode of ex- 



A 2 



