184 CONJUGATED ACIDS. 



mental science based on pure induction. It is, however, necessary 

 for the progress of science, that in accordance with the present 

 state of chemical theory we should establish certain general propo- 

 sitions, which not only furnish us with a comprehensive expression 

 for a number of frequently recurring facts, but guide inquiry in 

 various directions, and finally present us with certain points of 

 support for the due understanding of our scientific material. 

 Amongst these general propositions we reckon the method which 

 is now becoming tolerably common in theoretical chemistry, of 

 considering certain bodies as conjugated or copulated combinations. 

 We shall, however, place no more exclusive dependence on this 

 theory, as it has been carried out by Laurent and Gerhardt,* or 

 Strecker,f or Kolbe^ than on the theory of organic radicals and 

 of electro-chemical dualism of a Berzelius, or on the theory of 

 substitutions and metalepsy of a Dumas. If we even venture on a 

 reference to eclecticism, it must be in the choice of those supports 

 which one branch of science, in its early stage, is compelled to 

 borrow from another. It is only in this point of view that we 

 wish to justify the establishment of the group of conjugated acids 

 in zoo-chemistry. 



We have already had occasion to refer to a series of organic 

 acids which, according to the excellent investigations of Kolbe, 

 may be regarded as carbo-hydrogens conjugated with oxalic acid : 

 indeed, Kolbe is inclined to regard all the groups of acids we have 

 noticed, which contain 3 atoms of oxygen, as combinations of oxalic 

 acid with carbo-hydrogens. These illustrations are sufficient to 

 indicate the idea which we attach to the expression, conjugated or 

 copulated acids. We have become acquainted with acids which, 

 in opposition to the ordinary rules of chemistry, not only lose 

 nothing of their acidity, but (which is most singular) perfectly 

 retain their former saturating capacity, when united with another 

 and a more basic body ; after being combined with the so-called 

 adjunct (copula), this acid still saturates the same quantity of 

 base as if the organic matter associated with it did not exist; 

 and this dependent the adjunct which follows the acid as an 

 integral constituent in all its combinations, exerts an essential 

 influence on its physical and even on many of its chemical proper- 

 ties. Thus, for instance, oxalic acid, which in its ordinary state 

 is so readily decomposed by heat, becomes volatile by its conjuga- 



* Ann. de Chim. et de Phys. 3 Se'r., T. 24, p. 200-208. 

 t Ann. d. Ch. u. Pharra. Bd. 68, S. 47-55. 

 I llandworterb. d. Cheraie. Bd. 3, S. 439-444. 



