NOTE ON A NEW ELEMENT ALLIED TO MOLYBDENUM. O 



prisms, easily soluble iii water, and its aqueous solution gave the 

 following reactions : 



(1) Hydrogen sulphide, in presence of hydrochloric acid, 

 only gave a brown colouration without producing any precipitate, 

 but, on heating the solution to boiling, a dark brown precipitate 

 was formed (difference from a vanadate, which is not precipitated 

 by hydrogen sulphide either in the cold or when heated), the 

 fdtrate from it being quite colourless (difference from a molybdate, 

 which gives a blue coloured filtrate). 



(2) On reducing the solution with zinc and hydrochloric 

 acid, no colour appeared for some time, but, on standing, a blue 

 colour changing to brown was produced ; at the same time, a 

 substance having a metallic lustre adhered to the zinc. A solution 

 of pure ammonium molybdate of the same concentration similarly 

 treated at once turned blue, ultimately changing to brown, and 

 the brown solution, on long standing, deposited a dirty brown 

 amorphous substance. 



(3) Barium chloride, lead acetate, silver nitrate and mer- 

 curous nitrate all gave precipitates, soluble in nitric acid and 

 similar in appearance to the respective salts of molybdic acid, 

 except the mercurous salt. The barium salt forms a white 

 crystalline powder, slightly soluble in water ; the lead salt is a 

 white amorphous powder, insoluble in water ; the silver salt 

 forms a pale yellow precipitate, slightly soluble in water ; and 

 the mercurous salt consists of golden yellow crystals, insoluble in 

 water. Mercurous molybdate is obtained, under like conditions, 

 as a white or pale yellow amorphous substance.^^ 



1) Struve has observed that the milky precipitate of mercurous molybdate changes into 

 golden yellow needles through prolonged washing or on standing (Journ. prak. Cheni., 

 467, quoted in Dammer's Handbuch der anorg. Chem., II,I 628). 



