Thomson's System of Chemisiri/. 143 



principles, computed by the plainest arithmetic is 1.3015. 

 " Hence,'' says he, " fluate of- lime is composed of 

 Fluoric acid, . 26.418 . 1.0095. 

 Lime, . . 73.582 . 3.625." 



This being a simple question in the rule of three, he might 

 surely have contrived to solve it, in the course of two 

 consecutive editions of his complete system. For, 73.582 : 

 3.625: -.26.418 : 1.3015, and not 1.0095, as he has it. But 

 he is not content with forging this infinitesimal atom ; he must 

 turn it to good account. The following is a rather favourable 

 specimen of Doctor Tliomson's style of philosophizing. " If 

 we suppose fluate of lime to be a compound of fluoric acid and 

 lime, its composition will be, fluoric acid, 1.0095, 

 lime, . 3.625." 

 " From this we see that the weight of an integrant particle of 

 fluoric acid must be 1.0095. If it be supposed to be a com- 

 pound of one atonr of oxygen, and one atom of an unknown 

 inflammable basis, then, as the weight of an atom of oxygen is 

 one, the weight .of an atom of the inflammable base can be 

 only 0.0095, which is only the thirteenth part of the weight of 

 an atom of hydrogen. On that supposition, fluoric acid would 

 be composed of inflammable basis, 1.00, 

 oxygen, . 105.67. 

 " So very light a body, being contrary to all analogy, cannot 

 be admitted to exist without stronger proofs than have hitherto 

 been adduced. On the other, hand, if fluor spar be in reality 

 z.fiuoride of calcium, then its composition will be. 

 Fluorine 2.0095 

 Calcium 2.625 



So that the weight of an atom of fluorine would be 2.0095, 

 or almost exactly twice the weight of an atom of oxygen. This 

 is surely a much more probable supposition than the former. 

 But the question cannot yet be considered as fully decided." 

 What a heap of tautology, piled upon his own arithmetical 

 blunder ! He gives no intelligible account of Sir H. Davy's last 

 elaborate train of researches on fluoric acid. 



His second chapter is entitled, " Of simple incombustibles." 

 " By incombustible," says he, " I mean a body, neither capable 

 ot undergoing combustion, nor of supporting combustion." It 

 unites to all the supporters ; but the union is never attended 

 with the evolution of heat and light." Now wc apprehend, that 

 if the mutual action of two bodies, in any circumstances, be at- 

 tended with the evolution of heat and' light, one of them, at 

 least, must be a combustible. But azote forms with chlorine 

 ;uid iodine, compounds capable of exploding with heat and 

 light. A considerable portion of the article azote is taken 

 up with its acids, in order, as it were, to enlarge the book, 



