It 
CHEAP AND QUICK METHOD OF PURIFYING PYROLIGNEOUS ACID. 51 
PURIFICATION OP PYROLIGNEOUS 
ACID AND manufacture OP ACE- 
TATE OP LIME. ACCORDING TO 
THE METHOD ADOPTED BY CHE- 
MICAL MANUFACTURE. 
By Chiu Phil. Pbuckner, of Hof.* 
INTRODUCTION.-From his first con- 
nexion with the manufacture of pyroligneous 
aci'I, which has been on a great scale, Priickner 
endeavoured to fall upon the cheapestand quick- 
est method of i-urifying it from the foreign mat- 
ter with wh'ch it is mixed. This object has 
been I'nrtber prosecuted more recently by Dr. 
Reichenbacb, who has separated several 
substances which make their appearance dur- 
ing its purification. 
At the time when Priickner first engaged in 
the manufacture of this acid, these substances 
were unknown, and, consequently his view of 
the theory of the method of obtaining it pure, 
was quite dilferent from that pointed out by 
Reichenbacb. Now, however, when we pos- 
sess an accurate knowledge of the products 
which come over in the purification, viz. Creo- 
sote Picomare, Paraffin^ &c., we may expect 
that the process about to be discribed will be 
imjiroved, so that tlielast traces of foreign mat- 
ter may be entirely removed. Tlie author con- 
siders that the present memoir will not be 
destitude ofinterest for a considerable period 
to the practical chemist, as the process discrib- 
ed has been so frequently repeated and exa- 
mined, and that the publication wdl be of 
advantage to proprietors and managers of che- 
mical manufactories, who may, from the re- 
marks offered, be enabled to improve the pro- 
cess, by bringing the additional information 
which may be acquired by the consideration 
of new discoveries, to bear upon the subject. 
Many manufacturing chemists have long been 
endeavouring to purity pyroligneous acid in 
different ways. The process of Mollerat of 
Pellerey, who, by the formation of a great che- 
mical manufactory of this article, not only sup- 
plies it for the use of France, but also exports 
it, is sulficlently well known. It consists in 
forming the acetate of soda by the double de- 
composition of acetate of lime and sulphate of 
soda; the acetate of soda being then roasted, 
the empyreumatic matter is driven off and the 
pure acetate of soda remains. Tiie objection 
to the use of this salt is, that at an elevated 
temperature it melts, and that the surface of 
it gradually becomes dry, while in the interior 
much water still exist, and great difficulty is 
experienced in getting rid of it, while to the ace- 
tate of lime the same objection is not appli- 
cable. 
PREPARATION OP THE ACETATE 
OF LIME. — Tiie cmde pyroligneous acid 
wliich IS distilled from bard species of trees, as 
the beeci), oak, or alder, or from soft pines, 
receives a preparatory purification in the fol- 
lowing manner; — As much as possible of the 
oil mixed with tar which swims on the surface 
is removed mechanically. This is best etfected 
after the acid has been allowed to settle for a 
* Erdmann und Schweigger Seidel’s Journal 
fiir PractUche Chemie, iv. 21. 
day. A cask or large tub, with a double per- 
ferated inlaid bottom (einlegeboden) like the 
alkaline cask of the soap-boiler, is then taken 
and filled to the height of an inch with straw. 
This is overlaid by a piece of course sack-clofb, 
which is cut out in the form of the bottom. Over 
this is placed six inches of moist wood sawings, 
which are pressed down and smothed by means 
of a wooden club. To prevent the sawings from 
being displaced and from swimming about, they 
arecovered to the deuthof four inches with alar- 
er ofgravel. Acertain quantity ofirapure acid is 
then poured into this filtering apparatus which 
is termed a filtering cask, and passing through is 
discharged by a cock at the bottom. The tar 
is taken up by the gravel. Should the quan- 
tity of this be so great as to obstruct the pas- 
sage of the aciil, the sand may be stirred up 
from above with a ladle. 
The acid which has thus been filtered is now 
placed in a large cast-iron vessel, which is fill- 
ed lip to within ten inches of the brim. Heat 
is then applied, and during its action, lime- 
water previously passed through a hair seive, 
to free it from foreign particles, is added until 
tiie acid is neutralized. Theapproach to this 
point may be detected witliout the use oflitmus 
pafier, merely from the colour of the liquid, 
which becomes darker and passes from a black- 
ish brown into a deep brownish red colour. A 
great excess of lime is then added. To a bucket 
of neutralized acid, containing 120 pounds 
(1 iSlbs. troy) lialfa pound, (.4791bs. troy) is 
added in excess. This super-saturation is 
absolutely necessary ; because the lime com- 
bines with a great quantity of empyreumatic 
rosin and oily matter in the acid, forming inso- 
luble compounds which are separated first. Tlie 
next object is to bring the solution to the boil- 
ing point, and to avoid its boiling over. When 
a scum appears, the boiling should be carried 
on gently, and the matter swimming on the sur- 
face removed, as completely as possible, by 
means ofa ladle during the whole proce.ss of 
boiling. The solution in this manner being 
reduced to one half, is then cooled and clarified 
in the cask and allowed to stand for 30 or 
48 hours. In this state it is called the solution 
of the first boiling. 
To obtain the solution of the second boil- 
ing after the necessary clarification, the liquid 
is drawn otF into the same vessel after it has 
been cleaned, or into another iron vessel of the 
same description. The sediment is thrown 
npon a filtering cloth and set aside. For the 
second evaporation a shallow vessel is employ- 
fd, whose depth is not above 14 inches. 
Priickner uses a vessel of 4 or 5 feet long and 
2 to 3 broad as being most convenient. The 
fire burns under it, npon the grate of a wit-d 
furnace, and stretches under the bottom of the 
vessel towards tiie chimney. When the soln 
tion of the second boiling is heated, the fiee 
lime must be neutralized with pyroligneous arid 
as long as redriened litmus paper is coloured 
lilue. When evafiorated to two-tliirds or 
one half, the solution may be freed fioin any 
impurities by passing itt hrough a linen fiiterei , 
or placing it in a cask and allowing it to cool 
and settle. 
I he liquid having been treated in this war, 
should be again placed in the fiat vessel, and by 
