242 VINEGAR, CIDER, AND FRUIT-WINES. 



salt decomposing very readily at too high a temperature. As it 

 is, however, impossible, on the one hand, to properly observe the 

 temperature in the semi-cylindrical boiler, and, on the other, the 

 complete dryness of the salt is required so that as many of the 

 tarry substances as possible remain undissolved during the subse- 

 quent re-dissolving, the paste is removed in small portions and 

 spread out in flat cast-iron pans several of which are heated by 

 one fire-place. During the drying the salt must be thoroughly 

 stirred with iron shovels to prevent overheating. By careful 

 treatment a salt containing 75 to 78 per cent, of pure acetate is 

 obtained. 



By heating the calcium acetate in small cast-iron cylinders pro- 

 vided with a good cooling apparatus crude acetone is obtained 

 which can be purified by rectifying in a water-bath, shaking the 

 distillate with saturated solution of sodium hyposulphite, and dis- 

 tilling the separated crystalline body with soda solution and 

 dephlegmated by rectifying over calcium chloride. 



Calcium acetate is readily prepared, can be sent long distances 

 in a dry form from which the acetic acid can be readily separated 

 by a process to be described later on. Entirely pure acetic acid, 

 however, is not obtained from this salt, and it cannot be used for 

 household or medicinal purposes, nor in the fabrication of valuable 

 chemical products, for instance, certain aniline colors. Sodium 

 salt will have to be taken for the preparation of acid to be used 

 for these purposes. 



Preparation of Crude and Pure Sodium Acetate. 



a. The wood-vinegar freed from wood-spirit, acetone, etc., is 

 saturated in a vat with calcined soda (sodium carbonate), which is 

 gradually added, as otherwise the escaping carbonic acid causes 

 strong foaming up. The tarry substances appearing on the sur- 

 face are removed, and the brown fluid, after clarifying by standing, 

 is drawn off into flat cast-iron pans which are heated by the fire- 

 gases escaping from the carbonizing retorts. The concentration 

 of the fluid and skimming off of the tarry substances are continued 

 until the aerometer in the pan nearest the oven shows 27 B. = 

 1.23 specific gravity. The register is then closed so that the fire- 



