MANUFACTURE OF WOOD-VINEGAR. 241 



By saturating, however, at an ordinary temperature distilled 

 wood-vinegar with slaked lime, the filtered clear yellowish solu- 

 tion becomes turbid after standing for some time or by heating, 

 and a yellow-brown substance is separated by evaporation ; if the 

 salt solution is then sufficiently concentrated, a quite strongly col- 

 ored salt is again obtained. 



By slightly acidulating the solution of the calcium salt during 

 evaporation with hydrochloric acid, a small quantity of a yellow- 

 brown substance is separated, the previously strongly-colored 

 fluid becoming pale yellow ; by evaporating to dryness a calcium 

 salt of a yellowish -gray color is obtained. By slightly roasting 

 this salt and then distilling with hydrochloric acid, acetic acid of 8 

 B. = 1 .06 specific gravity, i. e., with about 48 per cent, of acetic 

 anhydride, is obtained. 



Preparation of Crude Calcium Acetate. 



When all bodies lighter than water have been distilled off from 

 the crude wood-vinegar, the retorts are allowed to cool off, and 

 after carefully opening the stop-cock, the tarry Deposit is first 

 drawn off; the wood-vinegar is then conducted into a large vat 

 in which the saturation is to be effected. When the point of 

 neutralization is reached, the solution is allowed to stand several 

 hours for the impurities of the lime to separate on the bottom and 

 the tarry substances dissolved in the wood-vinegar on the surface ; 

 the latter are then removed. 



The fluid is now slightly acidulated with hydrochloric acid (at 

 the utmost 4 pounds of crude hydrochloric acid to 22 imp. gallons) 

 and allowed to rest, whereby a deposit consisting chiefly of phenol 

 and other slightly acid substances is formed. The clear fluid is 

 then drawn off and evaporated in a cast-iron boiler over a free 

 fire. The tarry substances oxidized by the action of the air and 

 separating on the surface are constantly removed. When the 

 specific gravity (measured hot) has increased to 1.116, the separa- 

 tion of calcium salt in the form of crusts begins ; these crusts are 

 removed with an iron spatula. From this time on heating is 

 carefully continued until the contents of the boiler are converted 

 into a thick paste. The fire is then extinguished, the calcium 

 16 



