On the Atomic Theory. 16» 



been by no means duly imiJiessed with the importance of this ob- 

 servation of Mr. Dalton, till tliey were in possession of other facts 

 tjbserved by Dr.Tijomson and 'myself, in a more tangible form, 

 with regard to neutral and super-acid or sub-acid salts, &c." He 

 here refers the reader to Phil. Trans. ISOS, p. 74 and GS, to 

 which we will now pass. 



The pauer now under our consideration is entitled, On Super- 

 acid and Sub-acid Salts. Bv William Hyde WoUa&ton, M.D. 

 Sec. R.S. Read January 2S", iSOS. 



" Dr. Thomson," savs he, " has remarked, that oxalic acid 

 unites to stronlian as "well as to potash in two different pro- 

 portions; and 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 (juantity of base in their neutral com- 

 pomids." 



The Doctor tells us that he observed the same law to prevail 

 in various other instances of super-acid and sub-acid salts j and 

 as he considered it general, it was his intention to pursue 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 Che- 

 mical Combinations as explained and illustrated by Dr. Thom- 

 son, the inquiry which I had designed a})pears 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 ex- 

 pressed by some simple multiple of the number of its atoms." 



In the "foregoing paragraphs the Doctor to my great surprise, 

 and indeed to the surprise of every honest and hberal minded 

 man, transfers over to Mr. Dalton those principles which are so 

 clearly developed in my Comparative View, and which he him- 

 self was obliged to allow five years afterwards, as I have already 

 shown in this paper. 



But as the Doctor supposes that his intended experiments 

 might tlirow additional light on the theory of Dalton, he is de- 

 termined to go on with them. He commences with the sub- 

 carbonate of potash. 



" Experlwent 1. Sub-carbonate of potash recently jirepared 

 is one instance of an alkali having one-half the quantity of acid 

 necessarvfor its saturation, as may thus be satisfactorily proved. 



" Let' two grains of fully saturated and well crystallized car- 

 bonate of potash be wrapped in a piece of thin paper, and passed 

 up into an inverted tube tilled with mercury, and let the gas be 



* It would have been more correct to liuve said paiticlc to particle .shij^ly. 



extricated 



