1 74 French National Institute* 



cessary to saturate two hundred of hydrogen, whatever be' 

 the pressure and temperature. In this manner one may" 

 discover the hvdrogen contained in any air \Vhatever, eveit 

 if it form only a three-thousandth part. 



Messrs. Humboldt and Gay-Lussac have ascertained that 

 there does not exist a sensible portion of hydrogen in the 

 lower part of the atmosphere ; and the aerostatic excursion 

 of Messrs. Biot and Gay-Lussac, cind that of M. Gay-Lus- 

 sac alone, during which he rose to a much greater height, 

 have confirmed that there is no more at the greatest eleva- 

 tion to which it is possible to rise, and far afbove that where 

 the clouds are formed. Thus all the systems in which the 

 formation of rain and other meteors was ascribed to the 

 combustion of hydrogen gas, fall of themselves. 



There still remains some uncertaintv in regard to the 

 number of the new metals which are mixed with platina. 

 Were any confidence to be placed in the results hitherto 

 aimounced, there would he, besides iron, copper, chrome, 

 and lead, the metal discovered last year by Messrs. Fourcroy 

 and Vauqueliii, as well as by M. Descotils; two others 

 found in it by Mr. Tcnnant, and two discovered by Dr. 

 Wollaston called rhodium and palladium. 



Dr. Wollaston, indeed, according to letters frorn Lon- 

 don, discovered palladium, of which mention was made in 

 my two last reports, and kept the discovery secret, as if to 

 entrap chemists. He pretends that they have fallen com- 

 pletely into the snare, by imagining that this metal was a 

 compound of platina and mercury ; and, indeed, not only 

 have the attempts of M. dc Morvcau to imitate palladium, 

 accordingto the processof Mr. Chenevix,been unsuccessful, 

 but the case was the same with three German chemists, 

 Messrs. Rose, Gehler, and Richter. Th'is^palladium, there- 

 fore, ought to be a real metal. Is the case the same with 

 rhodium, osmium, and iridium? or do these substances 

 enter into the compositioji of each other, or into those 

 discovered by Messrs. Fourcroy, Vauquelin, and Descotils ? 

 This question can be determined only by time. 



Chemistry, however, appears to have acquired a new 

 metal named cerium, from the planet Ceres. It was ther 

 oxide of this metal which M. Klaproth considered as a new 

 earth, and named ocliroite. Two Swedes, Messrs. Hcssin- 

 ger and Bezelius, have supposed it to be a metallic sub- 

 stance ; and AI. \'auquelin, who repeated their experiments, 

 is of the same opinion. Nevertheless, as he was notable 

 to reduce it completely, some doubts still remain. 



We must leave also to time the confirmation of a disco- 

 very 



