104 Oil Chemical Equivalents. 



1808. The object of the atomic theory has been no where so 

 happily stated as by this philosopher, in the following sentence: 



" But, since the publication of Mr. Dalton's theory of che- 

 mical combination, as explained and illustrated by Dr. Thomson, 

 (System, 3d edit.) tlie inquiry which I had designed appears 

 superfluous, as all the facts I had observed are but particular in- 

 stances 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." 



It is evident from this passage, that the principle which pre- 

 sented itself to Mr. Dalton, on a review of the labours of other 

 chemists, had really occurred to Dr. WoUaston from his own, 

 and that he would unquestionably have been speedily led to its 

 fuil development. If Mr. Dalton had ever chanced to look into 

 the neglected book of Higgins, there would have been little merit 

 in his anticipation of what the advancement of analytical preci- 

 sion would infallibly have revealed in a very short period. 



Dr. Wollaston, in the above decisive paper, demonstrates, that 

 in the sub-carbonate and crystallized carbonate of potash, the 

 relation of the carbonic acid to the base, in the first is exactly 

 one-half of what it is in the second. The same law is shown to 

 hold with regard to the two carbonates of soda, and the two 

 sulphates of potash ; and being applied to his experiments on 

 tlie compounds of potash and oxalic acid, leads him to conclude, 

 tliat tlic neutral oxalate may be considered as consisting of 

 2 particles potash, 1 acid; the binoxalate as 1 and 1, or 2 po- 

 tash, with 2 acid ; the (juadroxalate as I and 2, or 2 potash, with 

 4 acid. 



We cannot withhold from our readers the following masterly 

 observations, which must make every one regret, that the ,first 

 development of the atomic theory had not fallen into such phi- 

 losophical hands. 



" But an ex|)lanation which admits a double share of potash 

 in the neutral salts (the oxalates) is not altogether satisfactory; 

 ami I am further inclined to think, that when our views are suf- 

 ficicndy extended, to enable us to reason with precision con- 

 cerning the proportions of elementary atoms, we shall find the 

 arithmetical relation alone will not be sufficient to explain their 

 mulual action, and that we shall be obliged to acquire a geome- 

 trical conception of their relative arrangement, in all the three 

 dimensions of solid extension. 



" For instance, suppose the limit to the approach of particles, 

 to be the same in all directions, and hence their virtual extent 



to 



