10 
ORIGINAL COMMUNICATIONS. 
must he deemed acids, agreeably to usage.^^ This definition 
I would now amend by leaving out the last sentence, and 
substituting therefor, the following: Also when any sub- 
stance is capable of forming a tertium quid with any acid 
or base agreeably to the "preceding definition, it must be 
considered as an acid in the one case, a base in the other. 
The definition, thus amended, takes in the organic acids 
and bases. In the form in which it was at first proposed, it 
has not been alleged defective by Berzelius ; but he has 
striven to show an incongruity in the attributes of his double 
salts, when contrasted with those resulting from the union of 
some of the acids and bases of his amphigen class ; which 
incongruity is, in his opinion, a sufficient reason for not 
considering them as simple salts, and their ingredients as 
acids and bases, agreeably to the opinions of De Bonsdorff 
and myself. 
Berzelius errs in confounding my opinions with those of 
De Bonsdorff. However I may have admired the sagacity 
with which that chemist investigated the pretensions of some 
haloid salts to certain attributes of acidity or alkalinity ; in 
my letter on the Berzelian nomenclature, I signified my 
unwillingness to rest my opinions upon a basis so narrow, as 
that which he had endeavoured to establish. I stated that I 
did not deem it necessary to appeal to his excellent observa- 
tions, proving certain attributes of acidity to exist in one case, 
those of alkalinity in the other. I alleged my definition to 
be founded on the conviction that the property of afiecting 
vegetable colours, on which that sagacious chemist lays so 
much stress, has not, latterly, been deemed necessary in acids; 
and that in bases it never was required. As respects them, it 
only served as a mean of subdivision between alkaline oxides 
and other oxibases. 
I am at a loss to discover in what part of my letter there 
was any language which could convey the erroneous impres- 
sion, that, in defining acids and bases I proposed to overlook 
properties, and to be regulated by attention to the number 
