204 Proceedings of the Royal Society of Edinburgh. [Sess. 
Couper writes the formulae of formic acid, acetic acid, and oxalic acid 
thus : — 
{ 0 -OH 
'O-OH 
c* 
a 
o 
o 
••• Q 
O 
to 
c - 
o 2 
( O 2 
( 0 2 
Hi 
c ■ 
• H 3 
c. 
| O- OH 
or the latter, “ Si Ton veut reunir foxy gene negatif a l’un des poles de la 
molecule, par la formule : — 
j'O 2 * 
n J 
VI 
U 
O 2 
0 OH 
( 0 ■■■OH 
Couper attaches to this a remark on the electronegative or electropositive 
state of the oxygen atoms that are united in the group 
(O-OH 
( O 2 
The oxygen atoms are in general in an electronegative state. But one 
oxygen atom — that one which is united to an electropositive element, such 
as hydrogen — thus takes on an electropositive state. The presence of the 
other two oxygen atoms united to carbon is necessary in order to bring the 
negative oxygen into the state which gives the substance the properties 
which are usually designated by the term acid. 
He adds : “ Ceci est un cas particular dune loi generale ; car on peut 
voir, d’apres cette theorie, comment la valeur electropositive ou electro- 
negative des elements modifie et conditionne mutuellement la valeur 
electropositive ou electronegative des autres elements.” 
At the close of his paper Couper deduces from his new views the 
formulae of salicylic acid and of the substance formed from it by the action 
of phosphorus pentachloride, to which he gave the name “ trichloro- 
phosphate de salicyle.” I shall postpone the consideration of these formulae 
till I have explained the reaction itself, and now turn to Couper’s fuller 
English paper “ On a New Chemical Theory.” The French version of this 
paper, which appeared soon after the publication in the Philosophical 
Magazine , is by Couper himself, and contains some additions made by him. 
* In the Comptes rendus “ C 2 ” is printed in error for “ O 2 .” 
