226 



48 to 28, and this is well confirmed by analysis, because we 

 discover in the solution nothing but red molecules mixed with 

 green ones." 



Page 334. *' I will say then of the sulphurets as I said of 

 the oxides, there are only two of them." 



Speaking of the oxide of copper : 



Page 351. " If we establish the calculation on this basis, 

 we find that a quintal of yellow oxide is composed of 86 of 

 copper and 14 of oxygen, whilst the black oxide to which we 

 wish to compare it, contains only 80 of metal and 20 of 

 oxygen ; or in other words, if copper condenses 25 per cent, 

 of oxygen to raise it to its maximum, it condenses only 16.3 

 to raise it to its minimum. Here then, we find, as in all other 

 combinations of oxygen, new reasons for recognising this law 

 of nature, which subjects the metals and combustibles to those 

 proportions from which we cannot separate them, however 

 various may be the circumstances under which they have 

 united." 



It really is a melancholy thing to read these papers of 

 Proust. He had advanced by the most careful steps to the 

 conclusion, that Jill combinations were made in proportions 

 defined by some law of nature, that they were weighed and 

 measured before they were united, and yet failed to see a 

 law. Richter used the words from the Septuagint, God 

 has made all things by measure, number, and weight; and 

 Proust uses a similar phrase with his " pondere et mensura," 

 from the Vulgate, leaving out the word number, which he did 

 not sufficiently see. He saw, with great clearness, that with- 

 out such constant proportion the products of nature would 

 lose their stability, and the characters of bodies could not be 

 depended on for permanence. We have here no difficulty in 

 judging how much he did, and how much he left undone ; how 

 far his own mind was advanced, and how it had merely specu- 

 lated. He tells us all distinctly. When he uses +1+2+3 of 

 proportions, he tells us it is merely for illustration, he did not 



