ACETIC ACID 



of the water, which, by the column in L o, is pressed to tRe upper part of the 

 cylinders, and runs over by the spout K. To this point a very short tube is attached, 

 which is bent towards the ground, and serves as an overflow. 



The condensing apparatus is terminated by a conduit in bricks covered and sunk 

 In the ground. At tie extremity of this species of gutter is a bent tube, E, which 

 discharges the liquid product into tho first cistern. When it is full, it empties itself, 

 by means of an overflow pipe, into a great reservoir ; the tube which terminates tho 

 gutter plunges into the liquid, and thus intercepts communication with tho inside of 

 the apparatus. The disengaged gas is brought back, by means of pipes M L, from 



one of the sides of tho 

 conduit to the under 

 part of the ashpit of 

 the furnace. These 

 pipes are furnished 

 with stopcocks, M, at 

 some distance in front 

 of the furnace, for 

 the purpose of regu- 

 lating the jet of tho 

 gas, and interrupting, 

 at pleasure, commun- 

 ication with the inside 

 of the apparatus. 

 The part of the pipes 

 which terminates in 

 the furnace rises per- 

 pendicularly several 

 inches above tho 

 ground, and is ex- 

 panded like the rose 

 of a watering-can, N. 

 The gas, by means of 

 this disposition, can 

 distribute itself uni- 

 formly under the 

 Vessel, without suffer- 

 ing the pipe which 

 conducts it to be 

 obstructed by the fuel 

 or the ashes. 



The temperature 

 necessary to effect the 

 carbonisation is not 

 at first considerable: 

 however, at the last, 

 it is raised so high 

 as to make tho vessels 

 red hot ; and tho 

 duration of the pro- 

 cess is necessarily 

 proportional to the 

 quantity of wood cai> 

 bonised. For a vessel 

 which shall contain 

 about 5 meters cube 

 (nearly 6 cubic yards ), 

 8 hours of lire is sufficient. It is known that the carbonisation is complete by tho 

 colour of the flame of the gas : it is first of a yellowish red ; it becomes afterwards blue, 

 when more carbonic oxide than carburetted hydrogen is evolved ; and towards the end 

 it becomes entirely white, a circumstance owing, probably, to the furnace being more 

 heated at this period, and the combustion therefore more complete. There is still 

 another means of knowing the state of the process, to which recourse is more 

 frequently had : that is the cooling of the first tubes, which are not surrounded with 

 water : a few drops of this fluid are thrown upon their surface, and if they evaporate 

 quietly, it is judged that the calcination is sufficient. The adapter tube is then 

 un luted, and is slid into its junction pipe ; the orifices are immediately stopped with 

 plates of iron and plaster loam. The brick cover, E, of the furnace is first removed 



