VIII. ACIDS.— Vinegars. 297 



2. As a secondary product in the distillation of alder, willow, 

 or dog-wood, in making charcoal for the manufacture of gun- 

 powder. 



Rectified pyroligxeous acid, Smoking liquor, Spiritus acidus 

 lif/ni. Essentia fuliginis. The rough acid redistilled in a copper 

 still. 100 gall, usually leave 20 gall, of viscid tarry matter in 

 the still. Transparent, brown, a strong smoky flavour, sp. gr. 

 1*013 half as strong again as the best common vinegar. Used to 

 preserve and smoke meat and fish by their being dipped in it for 

 at most two or three minutes, or to give them a smoky flavour by 

 rubbing them over with it by means of a feather or sponge. 



Spiritus buxi, P. L. 1745. From box wood. 



Acetic acid from wood, Pnrijied pyroligneous acid, Acidiim 

 aceticum ligni. Saturate rectified pyroligneous acid with lime, or 

 chalk, evaporate to dryness, gently heat it, stirring it all the time, 

 then dissolve it in water so as to mark 15 deg. Baume, mix the 

 solution with a saturated solution of sulphate of soda; sulphate of 

 lime falls down, and the liquid is pyrolignite of soda : evaporate 

 to 27 or 28 deg. and set by to crystallize ; evaporate the remaining 

 liquid again, and crystallize, (when no more crystals can be ob- 

 tained, the remainder is to be evaporated to dryness, and calcined 

 for carbonate of soda) ; gently heat the rough pyrolignite in 

 flat iron pans, until it flows quite smooth : the heat must never 

 be so great as to occasion the least fume : hence 8cwt. will require 

 about 24 hours to effect this. Dissolve the roasted pyrolignite in 

 water so as to mark 15 deg., decant and crystallize : add at once 

 oil of vitriol sufficient to saturate the soda, decant the liquid from 

 the sulphate of soda that is formed, and distil until the drops 



Iwne over coloured, then change the receiver. The clear acid 

 ; usually 40 acidimetric degrees strong, and its specific gravity 

 •057. 



2. Dissolve sulphate of soda in rectified pyroligneous acid, 

 -aturate the solution with chalk, strain, wash the sediment, add 

 the washings to the solution, and proceed to crystallize the 

 pyrolignite of soda as in the former process. Used to preserve 

 animal substances, and for the purposes to which acetic acid is 

 applicable. 



Acidum aceticum fortius, p. L. Acetic acid from wood, 

 100 gr. of which will saturate 87 gr. of crystallized subcarbonate 

 of soda, or 30 acid. i\Qg, '.32 strong : used by the London college 

 to make sugar of lead. 



HoNKY WATER FOR THE HAIR, Aqua mrllis, Honcy 41b., 

 very dry sand *2lb., put into a retort or body that will hold five 

 times as much, distil with a very gentle heat : a yellowish acid 

 water. Used to encourage the growth of hair. 



