of Molybdenum and some of its Compounds. 4-1 3 



denum, in which he showed that not more than three oxides 

 of molybdenum should be admitted, which however, by com- 

 bining with one another, were capable of producing several 

 intermediate combinations. These combinations, which have 

 very peculiar and distinct characters, had confused those 

 chemists who had previously experimented with this metal. 

 The method of preparing these oxides, their characteristic 

 combinations with acids, formed the chief object of the me- 

 moir. Soon after Berzelius* examined the behaviour of mo- 

 lybdenum towards sulphur, and that of the sulphuret of mo- 

 lybdenum towards electro-positive sulphurets, when he disco- 

 vered and accurately examined all that we have hitherto 

 known on this subject. 



Part I. 



Behaviour of Molybdic Acid to Bases. 



After this historical introduction, we will now pass on to 

 our experiments, the principal object of which was the most 

 accurate determination possible of the atomic weight of mo- 

 lybdenum. In the present state of chemistry, neither pains 

 nor time should be spared to determine the atomic weights of 

 the simple bodies as accurately as possible, for it is connected 

 with the important question, what elements have such num- 

 bers for equivalents as may be expressed by multiples of the 

 equivalent of hydrogen, and how far can this be admitted as a 

 general law. Now if we find, in fact, that the atomic weights 

 of several simple bodies are multiples of that of hydrogen, 

 this must some day lead to a number of other conclusions, 

 the vast importance of which to the whole science of chemistry 

 is not now apparent. If, on the other hand, experiments 

 have indicated deviations from this law, these also lead to im- 

 portant considerations. 



But in order to determine the atomic weight of a body, it 

 is first requisite to become acquainted with its properties and 

 some of its combinations. We shall therefore, to avoid fre- 

 quent repetition, first describe those combinations of molyb- 

 denum which we have examined. 



The following atomic weights for the metal have been used 

 in the theoretical calculations : — 



Mo = 588-966 (a.) Mo = 575-829 (b.) 



These numbers will be justified in the third part of this paper. 

 For the other bodies, we have employed the atomic weights 

 given by Berzelius in his Manual of Chemistry, vol. iii. Leipzig, 

 1845. 



* Kongl. Vet. Alcad. Handl. for 1825, p. 300. 



