502 
SECOND REPORT- 1832 . 
transparent gummy-like mass. This remarkable property is 
analogous to the change produced by heat on the common tar¬ 
taric acid ; but the effect, in this instance, is produced with 
extraordinary facility. 
This acid was first noticed by Berzelius ; and I had the 
pleasure of determining the above properties in his laboratory 
during the past summer. To his kindness also I am indebted 
for a supply of the acid, which I hope will enable me to prose¬ 
cute the investigation. This promises to be the more interest¬ 
ing, as I have reason to believe that the pyropctra- and the 
^yro-tartaric acids may prove, like the acids from which they 
are obtained, to be also isomorphous. 
Benzoic acid and Benzule .—The most important discovery 
lately made in vegetable chemistry, is that of Wohler and 
Liebig of the radical of the benzoic acid. It is the first ex¬ 
ample of a radical consisting of three elements, and promises 
to throw much light on the nature of the vegetable principles 
in general. 
By analysing the benzoate of lead, Berzelius had long ago 
found the composition of the acid to be = 14 C 4 6H 4 4 O. 
MM. Wohler and Liebig analysed the benzoate of silver, and 
deduced for the composition of the acid 14C + OH + 30; 
being the elements of an atom of water less than that given by 
Berzelius. The latter chemist, on repeating the analyses of 
both salts, found that of silver to be anhydrous, while that of 
lead contains an atom of water. The true composition of ben¬ 
zoic acid therefore is 14 C + 5 H + 3 O. 
The close connexion of benzoic acid and oil of bitter almonds, 
in which crystals of the acid are often deposited, as it was sup¬ 
posed from the oxidizement of the oil, led Wohler and Liebig 
to analyse it, when they found it to consist of 14C + 6H + 20; 
that is, it contains one atom of hydrogen more, and one of 
oxygen less, than benzoic acid. They consider both, therefore, 
to be compounds of the same radical, composed of 14 C + 5 H 
+ 20, which they propose to call Benzule, from matter ox 
base. If this radical be represented by Bz, then 
• 
Bz = benzoic acid. 
Bz -f H — oil of bitter almonds. 
If the oil be exposed to a current of chlorine, there are formed 
two products, Bz 4 Cl and Cl 4 H, chloride of benzule and 
muriatic acid. Treated with water, this chloride gives benzoic 
and muriatic acids. With hydrated bases, it gives a benzo¬ 
ate of the oxide and a chloride of the metal. Distilled with 
cyanide of mercury, it gives a cyanide of benzule and a chloride 
