on the Atomic Theory, 121 



of the very great benefit (to himself) " of representing the atom 

 of oxygen by unity, for it reduces the greater number of arith- 

 metical operations, respecting these bodies, to the addition of 

 unity." When a gentleman's arithmetic extends no farther than 

 the addition of unity, assuredly Dr. Thomson's plan is the only 

 safe one ; and he illustrates with peculiar naivete the intricacy of 

 the other plan, in which hydrogen being called 1, oxygen assumes 

 the formidable magnitude of 8. On multiplying the following 

 quantities of his favourite scale, viz., 3.5, 4, 4.5, 5, 5.5, 6.5, 

 and 7.5, by that unwieldy number 8, he has committed 3 blun- 

 ders \ his products being, as we have quoted them above, 



28 1 f 28 S= 



32 

 36 

 40 

 48 

 56 

 64 



instead of 



"We shall no longer be surprised at Dr. Thomson's antipathy 

 to the hydrogen scale ; though to a student somewhat advanced 

 in simple addition or multiplication, a short succession of 8's will 

 not be found very difficult to link together. Were we anxious 

 to rest our cause on the authority of names, as Dr. Thomson has 

 tried to do, we would adduce as its patrons, Sir H. Davy, Mr. 

 Dalton, Dr. Prout*, Dr. Henry, Mr. R. Phillips, and many 

 other chemists, who prefer the hydrogen to the oxygen radix. 

 Since the atomic theory is an indigenous plant, whose habitudes 

 and cultivation have been but partially studied abroad, we can- 

 not allow to the opinions of continental chemists much weight in 

 the discussion. 



We shall pass over, without further remark, Dr. Thomson's 

 Historical Introduction, as also his Second Chapter, entitled, 

 " Of the Atomic Theory," as presenting nothing of interest. 

 Having got mystified, to no purpose, among the canons of 

 Dalton and Berzelius, he strives to emerge, by a rank and file 

 parade of acids, with 3 atoms of oxygen, with 1 atom, with 2, 

 4, 5, 7, and 8 ; an arrangement turned to no subsequent account. 



His Third Chapter, u On the Specific Gravities of Oxygen and 

 Hydrogen Gases," is held forth as M the key-stone of the build- 

 ing," and therefore it merits our especial attention. It is divided 

 into three Sections, the first of which treats of the composition of 



* There is an advantage in considering the volume of hydrogen equal to 

 the atom, as in this case the specific gravities of most or perhaps all ele- 

 mentary substances (hydrogen being 1) will either exactly coincide with, or 

 be some multiple of the weights of their atoms," &c— Dr. Prout in Ann. of 

 Phil. vii. 113. 



