140 Chr. Phil. Pruckner on the [Aug. 



generally the specific gravity of 1-045-- 1'050, is colourless, 

 like water, and retains still a trace of the original empyreu- 

 matic odour. 



It contains also some sulphurous acid, and possesses cor- 

 responding characters, but loses it after being exposed for 

 some time to the air, in open vessels, the acid being con- 

 verted into sulphuric acid. 



It is obvious, from the quantity of acid recommended, 

 that, for the decomposition of the acetate of lime, an excess 

 of sulphuric acid is necessary ; since, for 100 parts of dry 

 salts, 62 parts of acid, excluding stechiometrical quantities, 

 would be sufficient. The peculiarity of Priickner's process, 

 he considers to consist in these proportions ; and he has 

 found that the addition of the excess of sulphuric acid is the 

 most powerful method of destroying or decomposing the 

 empyreumatic matter existing in the pyroligneous acid. In 

 consequence of inattention to this circumstance, the methods 

 of purification pointed out by several chemists, especially 

 that of B. Stolze, in his work, — Griindliche anleitung die 

 rohe Holzaure zu reinigen," &;c., must be either useless or 

 very inefficient. The method of previously heating the 

 acetate of lime, and of abolishing the drying in an open 

 vessel, over a free fire, is a decided improvement. For thus, 

 there is an inconsiderable or no loss by the decomposition 

 of the acetate of lime, with the least possible waste of time 

 and fuel. For manufacturing purposes, as for making ace- 

 tate of lead, and acetate of copper, there is no need of 

 repeated distillation, because the sulphurous and sulphuric 

 acid can readily be separated in the following manner : A 

 quantity of liquid dis-acetate of lead is to be prepared, to 

 about a pound of which the distilled acid is to be added, 

 until no more precipitate of sulphate of lead falls. The 

 latter should be collected and weighed. The quantity of 

 sulphuric acid in a given quantity of the acid, being thus 

 known, it is easy to calculate how much of the acetate of 

 lead solution will be required to throw down the whole acid 

 in the acetic acid. Some sulphate of lead is held in solution, 

 which is of little consequence in the manufacture of sugar 

 of lead. 



Further purification of the Pyroligneous Acid. — For 

 chemical and pharmaceutical purposes, it is necessary to 



