242 MEMOIR OF DR. D ALTON, AND 



1804 to Dr. Thomas Thomson, the very learned professor of 

 chemistry in the University of Glasgow, and by him they 

 were inserted in his system of chemistry. But it was not a 

 truth that could electrify the world, it was on a subject on 

 which few thought, one of which many said, '' what is the 

 use of it?" that miserable question which occurs to men to 

 whom the revelation of God's truth is of no interest, unless 

 an immediate advantage is promised. Dr. Thomson (Nichol- 

 son's Journal, Vol. 21, p. 87) says even four years after, 

 " This curious theory, which promises to throw an unex- 

 pected light on the obscurest parts of chemistry, belongs to 

 Mr. Dalton;" shewing that even then it required to be 

 taught even to chemists. We find in reality that for years 

 afterwards it was to most chemists a mere speculation. 



In a paper by Wollaston in the same volume, p. 164, he 

 says, " 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 superoxalates 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 superacid and subacid salts, I thought it not 

 unlikely that this law might obtain generally in such com- 

 pounds, 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 

 particular instances of the more general observations 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." 



