412 MM. Svanberg and Struve on the Atomic Weight 



had described. An important contribution to a more accurate 

 knowledge of this metal was now published by Buchholz*. 

 He directs the same method for the preparation of the mo- 

 lybdic acid as that employed by Hjelm, without, apparently 

 being aware that it had been described by him. He like- 

 wise states that the acid may be obtained pure and free from 

 alkali when the soda salt is treated with nitric acid. Two 

 years later Buchholz f published a more complete investi- 

 gation of molybdenum, in which his attention was principally 

 drawn to its several oxides. He admits six oxides, but is 

 not able to give good methods for preparing them pure. He 

 also analysed molybdic acid and the native sulphuret with 

 tolerable accuracy. He likewise describes a higher sulphuret 

 than the native mineral, but has no correct idea of the peculiar 

 nature of this compound; he was acquainted with its solubi- 

 lity in caustic alkalies and in alkaline sulphurets. We see in 

 him how a man of science opens a new path in experimenting 

 in order to explain all the phenomena, even to the minutest 

 details. 



The metallic nature of molybdenum was now ascertained 

 beyond all doubt; but there was wanting the man who should 

 lead us out of the labyrinth of white, blue, gray, yellow, brown 

 and red compounds which Buchholz had produced under dif- 

 ferent circumstances. The exploring of this labyrinth was 

 connected with the theory which, under the name of the theory 

 of definite chemical proportions, will hand down the name 

 of Berzelius to a late posterity. By experiments which Ber- 

 zelius % made in the year 1818, he showed that molybdenum 

 required a certain quantity of oxygen in order to form mo- 

 lybdic acid ; and by the analysis of the neutral molybdate of 

 lead, a subject to which we shall return in the third section of 

 our memoir, he ascertained the number representing the atomic 

 weight of molybdenum, assuming 100 as the atomic weight of 

 oxygen. 



After this was fixed, Brandes§ published his analyses of 

 some molybdates. He showed that molybdic acid forms with 

 ammonia two distinct crystalline salts, although he gives merely 

 the analysis of one. He also analysed the neutral soda salt, 

 and prepared several insoluble salts by double decomposition. 



In 1825 Berzelius || published an investigation of molyb- 



* Scherer's Journal der Chem., 1802, vol.ix. p. 485. 

 t Gehlen's Allgemeincs Journal der Chem., 1805, vol. iv. p. 598. 

 X Afhandlingar in Fysik, Kemi och Mineralosie, 5te delen. Stockholm, 

 1818, sid 475. 

 § Schweigger's Journal der Chem. und Pkys., 1820, vol. xxix. p. 325. 

 II Kongl. Vet. Akad. Handl. for 1825, sid 145. 



