260 



VINEGAR, CIDER, AND FRUIT- WINES. 



her of cubic centimetres of nitrate of silver solution consumed 

 by 0.028, or, still better, as the lime is seldom pure, by 0.03. 

 The product gives the quantity of lime in grammes required for 

 1 liter of acetic acid. If calcium aetate is to be used, multiply 

 by 0.079, or by 0.08 if the calcium acetate is not absolutely pure. 

 ' Rectification is executed with steam. In Fig. 61 the steam 

 enters through the vertical pipe near the bottom of the still and 



Fig. 61. 



circulates in a coil ; the condensed water can be discharged through 

 a pipe near the influx aperture. 



The first and last portions are not entirely clear ; they are col- 

 lected by themselves, and, after mixing, allowed to clear by stand- 

 ing, when the greater portion can be siphoned off. The turbid 

 residue is added to a fresh mixture of acetate and hydrochloric 

 acid to be subjected to distillation. 



Volckel has further found that it is not necessary to use the 

 roasted gray calcium acetate, but that, with a slight modification 

 of the process, the acetate prepared from crude wood-vinegar 

 answers nearly as well. The crude wood-vinegar is filtered 

 through charcoal and being freed from wood-spirit and acetone 

 by distillation, is saturated or even slightly supersaturated in an 

 iron boiler with slaked lime (litmus paper should be colored 

 slightly blue). The solution is boiled for some time, and, after 

 clarifying, is evaporated in an iron pan to about one-half its vol- 

 ume, the resinous and sooty impurities appearing upon the surface 

 being constantly removed. 



