THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 

 DECEMBER 1848. 



LXIII. On the Atomic Weight of Molybdenum and some of its 

 Compounds. By L. Svanberg and H. Struve*. 



[From the Transactions of the Royal Academy of Sciences of Stockholm 

 for the' year 1848. J 



Introduction. 



"C'ORMERLY all those minerals occurring in nature which 

 -*- possessed a leaden hue and rubbed off were designated 

 by the name of molybdena. Under this name were therefore 

 comprised, not only certain plombiferous minerals, but others 

 widely different, as graphite, the native sulphuret of molyb- 

 denum, and manganese ore. With the progress of science 

 these minerals were more carefully examined and distin- 

 guished from each other. Cronstedt was the first who separated 

 plumbago from the sulphuret of molybdena as distinct, 

 although closely allied minerals. The views respecting these 

 minerals were however long divided. Many persons, from 

 the similar action of heat upon them, both being volatilized, 

 and their similar outward appearance, asserted them to be of 

 the same nature. It was naturally impossible to decide this 

 question by mere external characters ; and it consequently re- 

 mained doubtful until chemistry made an advance, or in other 

 words, until it became evident that all questions could not be 

 correctly solved by the mere examination in the dry way. 



It was reserved for Scheelef? who may justly be termed the 

 founder of chemistry in the humid way, and who showed what 

 conclusions might be drawn from the combinations obtained, 

 to establish, in a memoir which he laid before the Royal 

 Academy of Stockholm in 1778, the differences between gra- 

 phite and the native sulphuret of molybdenum, by the disco- 



* Translated by Dr. W. Francis from Erdmann and Marchand's Journal 

 fur Praktische Chemie for August 15, 1848. 



f Kongl. Vet. Akad. Handlingar for 1778, S. 247- 

 Phil. Mag. S. 3. Vol. 33. No. 224. Dec. 1848. 2 E 



