Obituary.— César Mansuete Despretz. 399 
In 1824 he became professor of pirate in the college of Henry IV, 
where he had for some time acted as tutor, and in 1837 was appointed 
long. In 1841 he was appointed to fill the vacancy in the Praia 
caused by ps death of the illustrious physicist Savart, and in 1858 w 
called to the presidency of the Aca 
His first publications date from 1818, “when he began with important 
researches upon the latent heat of vapors. In 1819, he was occupied 
with the elastic force of vapors. At that time, physicists agreed with 
Watt that the total amount of heat contained in a given weight of satu- 
rated vapor of water is constant at all pressures and at all temperatures. 
Despretz, on the contrary, concluded from his own experiments, that the 
latent heat increases with the pressure and the temperature, but to a less 
amount than — increase of the temperature. His results are now uni- 
ome i 
The dia which he published in 1822 on the causes of animal 
heat, ai wos ed” by the Academy, which had proposed this subject 
for investigation :—“ Compare the heat developed by a warm-blooded 
ea b 
On this occasion Despretz gave his attention to a series of researches upon 
the composition of the air and the respiration of reptiles; perceiving that, 
besides the vit acid formed in the respiration of these animals, there 
was also some nitrogen 
He also Rcsiuared that fishes have a higher temperature than that of 
the water in which they live ;—that new-born infants have a temperature 
about two degrees higher than that of man, and that the same is true 
es animals, ete. 
8 researches upon the conductibilities of bodies were also productive 
of eres which have been accepted by science, and which are almost 
entirely confirmed by corresponding results obtained by Mr. 
inbu man In this line of research, Despretz was preceded only by 
1825, he was mfisher with fe aay of the heat deelope in the 
same quantity of heat for the same volume of sie rbed. 
While studying the density of gases at different fein, in 1827, he 
2 ete that all gases follow Mariotte’s law, while Hs are strongly 
compressed, and that they possess variable compressibiliti 
the modifications which metals suffer, under the combined action of neat 
and ammoniacal gas, discovering the fact that iron will combine directly 
with nitrogen, forming a nitrid. But only recently, and as one — of 
the great labors of St. Claire Deville and Woéhler, has it becom 
tainly known that nitrogen eal a very = affinity for many of the 
metals, and is fitted to combine with them 
