HISTORY OF THE ATOMIC THEORY. 225 



which I have indicated become an obstacle to this progres- 

 sive action." 



"A little before this are to be found the facts on which 

 this illustrious chemist establishes the theory of progressive 

 oxidations, which he opposes to that which I have given out 

 on different occasions, and of which the base is, that the com- 

 bustible bodies are arrested at fixed terms of oxidation, in the 

 same way as we see to be the case with sulphur, phosphorus, 

 carbon, azote, and the greater part of the metals." 



Page 328. After shewing that the fine lead powder got 

 by shaking the metal in a bottle is a mixture of metal and 

 oxide of lead, and not a low and varying degree of oxidation, 

 he adds ; 



" But is each of these molecules, one might say, suddenly 

 at one leap elevated from to 9, to 12, to 25 per cent ? And is 

 it possible that they do not pass successively all the ascending 

 terms which the imagination can conceive possible between 

 the two extremes ! I reply, that it is impossible in the actual 

 state of things to say if the oxidation follows or does not 

 follow this progression, because in the calcination of a metal, 

 of lead for example, the senses are not struck with any 

 phenomenon which can guide the judgment in the choice 

 between two opinions ; but although we do not see intui- 

 tively that which occurs actually in calcination, we are not 

 hindered from judging clearly by the aid of numerous analo- 

 gies which the field of combination offers." 



Page 330. ** Let us mix the green sulphate of iron with the 

 red, each base will hold its own amount of oxygen, and there 

 will be no conciliation between the two, no division which 

 will bring forward to us those intermediate oxidations which 

 the mind would desire to discover. Is it a piece of iron which 

 we throw into the red sulphate ? We see the base of the salt 

 descend to 28, not by a retrograde march which arrests each 

 of these particles at 47, at 46, at 45, &c. of oxidation, but by 

 the instantaneous lowering of each from the limit (or term), 

 2 a 



