1908-9]. Life and Chemical Work of Archibald S. Couper. 225 
C 
n a . 
i C- H 2 
( C-H 
| C H 
C • 
i (; • !>•• ii. 
11,(0 = 16). 
Monochlorophosphate of Salicyle. 
Ill, 
C< 
c h 2 
I C H 
j C-H 
| C- 0 •() 
0 2 
1 0-0 
c 
c 
c 
j 0 2 
) Cl 
III, (0 = 16). 
c h 2 
c- -H 
j C H 
I C 0 
0 
c 
••••o 
1° 
j Cl 
Phosphosalicylic Acid. 
IV,. 
c 
c 
j 
C H 2 
\ C H 
| C-H 
( C O -op 
: ( 0 2 
C ) 
( O -OH 
0 2 
O --OH 
0 - OH 
c 
c 
IV, (0 = 16). 
C-H 2 
C H 
C -H fO 
} C - 
OP 
OH 
C 
jO ! OH 
) OH 
These formulae, I a , II a , III a , and IV a , are structural formulae, in our 
present meaning of the term. They strike us as still more modern when, in 
them, we use 0 = 16, that is, divide the number of oxygen atoms by 2 (or 
write O for Couper ’s O 2 or — 0 — O — ), as is shown in the formulae X 6 , II 6 , 
III,, IV,. The formulae XI a and II, show us what has become of the 
phosphorus pentachloride, the residue of which replaces the hydrogen of 
the hydroxyl and of the carboxyl in the salicylic acid. We see that 
Couper supposed the hydroxyl and the carboxyl to be attached to the 
same carbon atom. 
VOL. XXIX. 
15 
