224 
Proceedings of the Royal Society of Edinburgh. [Sess. 
The “acide phosphosalicylique ’ is tribasic, and Couper regarded it “comme 
une combinaison conjugee d acide phosphorique et d ’acide salicylique, 
PhH 3 0 8 + C 14 H 6 0 6 = C 14 H 7 Ph0 12 + 2HO.” 
These results, says Couper, do not, in all points, agree with the observa- 
tions published by Gerhardt, Chiozza, and Drion, and raise a doubt as to 
the existence of the salicyl chloride described by Gerhardt, a product that 
has never been analysed. Couper then points out that the formation of 
salicyl chloride from salicylic acid or from gaultheria oil could not take 
place without the production of phosphorus oxychloride, whereas he had 
observed only traces of this substance. Whether these contradictions were 
the result of some accident or of special conditions under which the various 
observers worked, could only be decided by new investigations. 
The formulae of the three new compounds containing phosphorus, which 
he had obtained from salicylic acid, were substantiated by Couper by means 
of a series of analyses. He used empirical molecular formulae and the 
small equivalent weights C = 6 and 0 = 8. 
A week after the publication of this paper on salicylic acid, there 
appeared, in the Comptes rendus , Couper s first communication on a new 
chemical theory. He applies his new theory to the derivation of constitu- 
tional formulae for salicylic acid and for his “ trich loroph ospl iat e de salicyle,” 
assuming C = 12, but retaining 0 = 8. 
In the somewhat later paper, published in the Edinburgh New 
Philosophical Journal , he gives constitutional formulae, not only for these, 
but also for the “ monochloropliosphate de salicyle ” and the “ acide phos- 
phosalicylique.” These formulae are given below as I a , II ft , III a , and IV a , 
and beside them I have given, as I b , II b , III & , and IV & , the formulae obtained 
by doubling the atomic weight of oxygen : 
Salicylic Acid. 
R. 
I, (0 = 16). 
( C" H 2 
(C H 2 
C 
c 
( C - TI 
( C • H 
(' C 11 
( C - H 
c 
c 
(c -0 -OH 
( C OH 
: (O 2 
! ( o 
C 
c < 
(O-OH 
( —OH 
From this formula (I*) for salicylic acid Couper derives the following 
formula for the “ terchloropliosphate of salicyle ” : — 
