1 826.] Biographical Sketch of M. Proust, 245 • 



Morveau : this favour was as flattering to him as it was honour- 

 able to those who granted it; The advantage belonging to the 

 title of Academician, which he enjoyed from this period, and a 

 pension of 1000 francs, which he derived from the hberahty of 

 the late king, Louis XVIII. contributed to render his existence 

 more happy towards the end of his hfe. 



After his nomination to the Academy of Sciences, Proust 

 returned to Angers, his native city; he there wrote several 

 memoirs, some of which were addressed to the Institute ; he 

 also sent to the Academy of Medicine some researches into one 

 of the causes which occasion the formation of calculi. Lastly, 

 he was occupied in an important work upon urine, when death 

 snatched him from science ; it is, however, to be hoped, that 

 this work, which was considerably advanced, will not be entirely 

 lost, and that the first part of it will be pubhshed. 



As we can only give a concise account of the scientific claims 

 of Proust, we shall not give the titles of all the memoirs which 

 he published in most of the records of science, especially in 

 the Journal de Physique, from 1771 to the present period. We 

 shall name only the principal : we first mention his Memoirs on 

 Prussian Blue, in which he shows that the colour of this sub- 

 stance depends upon the degree of oxidation of the iron, that 

 this, oxidation cannot exist in all proportions, but that it stops 

 at two fixed points, and that all the shades observed in prussian 

 blue are derived from a mixture of the two prussiates of iron ; 

 he states a great number of the properties of this singular 

 product, which has since exercised the sagacity of the most 

 distinguished chemists, and upon the nature of which they are 

 not yet agreed. We will also mention his work upon tin, which 

 is a very remarkable memoir, replete with new and curious facts, 

 and in which he decidedly proves, that tin, as well as iron, is 

 susceptible of only two degrees of oxidation ; he very minutely 

 describes the two chlorides of tin ; he explains the deoxidizing 

 action of the protochloride upon indigo, the salts of peroxide of 

 iron and of copper ; he first showed the existence of a chloride 

 of copper differing from the green chloride, and of a protoxide 

 of the same metal, which was not suspected before his labours. 

 'His researches on the oxides of cobalt and nickel are of great 

 importance, and so also are those upon antimony, arsenic, mer- 

 cury, silver, and gold, upon the metalHc sulphurets and upon 

 gunpowder. 



We observe in reading these memoirs, that independently of 

 the peculiar merit of each, they are all intended to prove that 

 no combinations of bodies with each other occur in indefinite 

 proportions, but that they are subject to invariable and fixed 

 proportions; to thdit iwndiis natur(B, as he himself says, "which 

 characterizes all the true compounds of art and of nature,'* 

 This opinion of Proust respecting definite propoitions, which 



