MANUFACTURE OF WOOD- VINEGAR. 227 



ratus h, but cannot re-enter the retorts. This is of no slight im- 

 portance, for if there were no water joint and the vapors should 

 from any cause suddenly cool off, the external air might penetrate 

 into the retort and the latter being filled with inflammable gases 

 and vapors of a high temperature an explosion would necessarily 

 follow. For making the water-joint it suffices for the elbow- 

 pipes to dip f to 1 inch into the fluid in the receiver. But as the 

 fluid constantly increases provision must be made for its discharge 

 through a pipe, placed below or on the side, into a collecting vessel 

 located in another apartment. The charcoal is at the end of the 

 operation raked into sheet-iron boxes or square pits sunk in the 

 floor and lined with fire brick ; both chests and pits are fitted 

 with close fitting covers, since if air is not excluded the charcoal 

 from its power of condensing gases in its pores, becomes so much 

 heated as to take fire spontaneously. By shutting the charcoal 

 in, the absorption is so far retarded as to keep the heat below the 

 point of ignition. 



In many factories the charcoal is abstracted from the carbon- 

 izing cylinders by means of the following apparatus : An iron 

 diaphragm about the size of the interior of the retort is placed 

 near the mouth of the latter, having a chain attached to it which 

 runs through the whole length of the carbouizer. The workman 

 by seizing this chain with a suitable instrument draws out nearly 

 the whole of the charcoal at once, and with less risk of breaking 

 it than when rakes are employed. 



Condensers. ^Yood ? as will be shown later on, yields more 

 than half its weight of condensable fluids and among them some 

 with a low boiling point. The necessity for good condensation is, 

 therefore, evident, and the more so as the quantity of non-con- 

 densable gaseous bodies is very large and with incomplete cool- 

 ing would carry away a considerable portion of valuable bodies. 

 Kestner's apparatus, Fig. 55, answers all demands. In a long, nar- 

 row trough of wrought-iron or wood lies a series of straight, wide 

 copper pipes, with a gradually decreasing diameter. The pipes 

 are slightly inclined, so that the fluid running in at the highest 

 point flows out at the lowest. Outside the trough the pipes are 

 connected by movable elbow-joints. One end of each pipe is 

 firmly fixed to the wall of the trough, while the other, to permit 



