it's properties and composition MUNRO 11 



"When molybdic acid is reduced in solution by sulphuretted 

 hydrogen, sulphur dioxide, stannous chloride, nascent hydro- 

 gen, etc., a blue color is obtained, due to the formation of an 

 oxide or oxides between the di- and the tri-oxide. The solution 

 deposits a blue precipitate of this oxide which contains (?) 

 water. It is termed "Alolybdenum Blue." 



It will be seen from the above extracts that very little is 

 definitely known concerning the properties or composition of 

 Molybdenum Blue. Attempts were made by various investi- 

 gators to find it's formula. A number of different formulae 

 have been brought forth. These will be briefly noted, without 

 giving any details of the methods by which they were obtained. 



The formula of lowest molecular weight is that given by 

 Rammelsberg. He assigns to the Blue the formula M02 05,= 

 M0O2M0O3. Others regard it as M03 08 = Mo02.2Mo03. 



Guichard suggests M05O14 6H2 O = MoOj 4 M0O3. 6H2O. 

 Zsigmondy says "The formula is supposed to he M03 0%, SH^O. 

 According to Klassen, it consist of complex derivatives of an 

 oxide M02O5 and Molybdic acid, analogous to phospho- 

 molybdic acid. 



Since 1917, no further work has been published on the 

 question of its composition. This research was undertaken 

 with the object of determining the correct formula for Molybde- 

 num Blue and to make a study of its properties. 



Demonstration 



A solution of ammonium molybdate was the first requisite. 

 This was made according to the method given by Noyes. A 

 solution of stannous chloride was also made. This was obtained 

 by dissolving pure tin shot in concentrated hydrochloric acid 

 and diluting it to required strength. Some mctalic tin was 

 kept in the bottom of the flask. 



On attempting to obtain Molybdenum Blue by adding a 

 portion of the SnCh solution to some of the solution of am- 

 monium molybdate, a blue coloration was first obtained, but 



