1908-9.] Life and Chemical Work of Archibald S. Couper. 269 
According to the rational theory which I seek to develop in another paper,* * * § the 
constitution of this body may he represented as : — 
( C- H 2 
(C • H 
( C II 
C I 
( C O Oh 
i (O 2 Ip-’-ci 3 
c ' I 
j 0""0j 
It is a tertiary 
derivative ; the 
secondary deri- 
vative, salicylic 
acid, being 
( C H 2 
C 
( C H 
( C H 
C • 
! C O OH 
c 
( O 2 
1 0 OH 
The reaction, of which this body is the result, is represented by the following 
equation f : — 
C 7 H 6 0 6 + PCI 5 - 2HC1 = C 7 H 4 C1 3 P0 6 . 
This is the same body which, unpurified, Gerhardt calls the chloride of salicyl, 1 
and Chiozza the chloride of chlorobenzoil,§ or the hydrochlorate of monochloro- 
benzoic acid. In order to determine rigorously whether the body produced by 
Chiozza from salicylic acid was really the same as that which Gerhardt and I have 
obtained from the oil of gaultheria, I investigated the action of the perchloride of 
phosphorus upon the pure acid. The reaction which takes place between the two solid 
bodies is less violent than when the oil was employed. Nevertheless, in this 
instance also the action is prompt. After the vapour of hydrochloric acid has passed 
off, the residue in the flask is identical with that which remains when the oil of 
gaultheria is employed. These two products distil in identically the same manner, 
with the same physical appearances, while the products of distillation produce 
exactly the same results upon analysis. 
These products display also entirely the same results in all their reactions. 
The terchlorophosphate of salicyl obtained by either process is very soon decom- 
posed by water in the cold, and immediately, upon the application of heat, the 
products being hydrochloric, phosphoric, and salicylic acids. 
Chiozza’s monochlorobenzoic acid, which he believes to be produced along with 
hydrochloric acid in the decomposition of this body, is only salicylic acid || rendered 
impure by hydrochloric and phosphoric acids. 
Chiozza did not succeed in producing the reaction for salicylic acid by the 
perchloride of iron. Nor is it to be observed till the liquid containing the phos- 
* Phil. Mag., August 1858. 
t Couper gives here the equation representing the action of PC1 5 on salicylic acid (of which he 
speaks a few lines further on) instead of that for the action on gaultheria oil. 
X Comptes rendus, xxxviii. 34. 
§ Annates cle chim. et de phys. [3], xxxvi. 102. 
|| Couper is mistaken in this. Chiozza certainly had in his hands cldorobenzoyl chloride and 
chlorobenzoic acid. 
