C 9 6 3 
V. On Super-acid and Sub-acid Salts. By William Hyde 
Wollaston, M. D. Sec. R. S. 
Read January 28, 1808. 
In the paper which has just been read to the Society, Dr. 
Thomson has remarked, that oxalic acid unites to strontian as 
well as to potash in two different proportions, and that the 
quantity of acid combined with each of these bases in their 
super-oxalates, is just double of that which is saturated by the 
same quantity of base in their neutral compounds. 
As I had observed the same law to prevail in various other 
instances of super-acid and sub-acid salts, I thought it not un- 
likely that this lav/ might obtain generally in such compounds, 
and it was my design to have pursued the subject with the 
hope of discovering the cause to which so regular a relation 
might be ascribed. 
But since the publication of Mr. Dalton's theory of 
chemical combination, as explained and illustrated by Dr. 
Thomson,* the inquiry which I had designed appears to be 
superfluous, as all the facts that I had observed are but par- 
ticular instances of the more general observation of Mr. 
Dalton, that in all cases the simple elements of bodies are 
disposed to unite atom to atom singly, or, if either is in excess, 
it exceeds by a ratio to be expressed by some simple multiple 
of the number of its atoms. 
* Thomson’s Chemistry, 3d Edition, Vol. III. p. 425. 
