94 VINEGAR, CIDER, AND FRUIT-WINES. 



more than from 23 to 25 feet, an ordinary suction-pump may be 

 used for the purpose, though a forcing-pump is better, it doing 

 the work more rapidly. The pump must be constructed of 

 material entirely indifferent to acetic acid (wood, glass, hard 

 rubber, tin, or a strongly silvered metal). 



Any metallic vessels used in the factory should be of pure tin, 

 i. e., unalloyed with other metals, it being the only metal entirely 

 indifferent towards acetic acid, but unfortunately it is too soft to 

 be suitable for the construction of pumps. 



The pump is generally located in the immediate neighborhood 

 of the collecting vessels, its suction-pipe being divided into three 

 branches and fastened into the latter. If one of the collecting 

 vessels is to be emptied, the respective spigot is opened and the 

 spigots of the other suction-pipes closed. 



Ordinary well or river water being used in the preparation .of 

 the alcoholic liquid, the temperature of the latter does not gene- 

 rally exceed 54 F., and if it were thus introduced into the gene- 

 rators acetification would be very sluggish until the temperature 

 rose above 68 F. Independently of the loss of time, there would 

 be the further danger of injuring the development of the vinegar 

 ferment; hence it is necessary to heat the alcoholic liquid to the 

 temperature required. This is best effected by passing it through 

 a coil surrounded by hot water. Fig. 29 shows an apparatus es- 

 pecially adapted for heating the alcoholic liquid. In a copper or 

 iron boiler filled with water, which can be heated from below, is 

 a coil, 8, of pure tin ; it enters the boiler above at a and leaves it 

 at b, so that the place of influx is at the same level with that of 

 discharge. With this form of construction the coil of course re- 

 mains always filled with liquid, which with the use of pure tin is, 

 however, of no consequence ; besides, this can be remedied by 

 placing on the lowest coil a narrow pipe, R, which projects above 

 the edge of the boiler and is bent like a siphon. By opening the 

 spigot h the fluid contained in the coil runs off through R. 



The rising pipe of the forcing-pump is provided with an ar- 

 rangement by which the alcoholic liquid can be brought either 

 directly from the collecting vessels into the reservoirs or first 

 forced through the heating apparatus. It consists of a prismatic 

 wooden body provided with three spigots. By closing spigots 2 



