BENZOIN. 20% 
of the powdered resin and slaked lime, evaporating the filtrate to 
one-sixth of its bulk, treating with bleaching-powder solution, 
and then boiling with hydrochloric acid until all the chlorine has 
been removed. The acid separates out on cooling, and is re- 
crystallized from hot water. 
The first process yields the most fragrant acid, the second yields 
the largest result. 
Benzoic acid is prepared from the urine of cows or horses by 
allowing it to stand for several days, clarifying with milk of lime, 
evaporating the liquid to one-fourth of its bulk, and precipitating 
the benzoic acid with hydrochloric acid. As the evaporation 
produces a very unpleasant smell, it is better to precipitate the 
excess of lime by carbonic acid and add ferric chloride to precip- 
itate ferric benzoate, which is then decomposed by hydrochloric 
acid. The acid thus obtained is purified by being re-dissolved in 
milk of lime with the addition of a little bleaching-powder solution, 
separated by hydrochloric acid and re-crystallized from hot water. 
The final product (acidum benzoicum ex urina) is not only devoid 
of the fragrance of “ Benzoin-benzoic acid,” but it still smelis of 
urme, and is consequently unfit for purposes of perfumery. 
About 2 lbs. of acid are obtained from 1000 Ibs. of urine. This 
variety is commercially known as “ urine-benzoic acid” and 
** German ” benzoic acid ; it is probably used as an adulterant to 
the sublimed acid. When the “ urine acid ” is sublimed, it may, 
as averred, lose its offensive smell, but it does not contain the 
adherent volatile oils which add to the fine odour of the natural 
product. 
Artificial benzoic acid is now prepared readily and cheaply from 
toluene, which is a bye-product in the manufacture of nitro- 
benzene. Toluene is first converted into benzyl chloride (as 
previously described). 100 parts of this are then boiled with 300 
parts of nitric acid sp. gr. 1°313 and 200 parts of water for 
about 10 hours in an apparatus connected with an inverted con- 
denser, until the smell of benzyl chloride and benzaldehyde has 
disappeared, and the liquid solidifies on cooling to a crystalline 
mass, no oily drops being formed. 
This form of acid retains a peculiar odour of nitrobenzene, 
which is more noticeable when the package containing it is first 
opened. It is known as “ Tolnene-benzoic acid,” and is largely 
made in Germany. As neither the ‘ hippuric ” nor the “ toluene- 
