of Molybdenum and some of its Compounds. 529 



The anhydrous salt contains — 



Potash. . . 11-812 

 Molybdicacid 88*188 

 In this analysis the molybdic acid was estimated from the 

 loss. These results correspond with the pentamolybdate of 

 potash previously described, with this difference, that the salt 

 dried at 212° contains 4-891 water of crystallization, corre- 

 sponding to 2 atoms. The theoretical composition of the 



salt is — 



a. 



1 at. Potash . . . 588'856 

 5 at. Molybdic acid 4444-830 



2 at. Water . . . 224-958 



5258-644 100*000 5192*959 lOO'OOO 

 If the yellow salt of ammonia is dissolved in ammonia and 

 chloride of barium added, a white precipitate is formed, which 

 possesses all the properties of the neutral molybdate of baryta 

 described in the first part of this paper, with this sole differ- 

 ence, that when an acid is added to it, it instantly assumes a 

 yellow colour. We have made two analyses of this salt, pre- 

 pared at different times. 



I. 0*780 grm. salt lost 0*0143 grm. on ignition, and gave 

 0*5994 sulphate of baryta = 03905 baryta. 



II. This salt was analysed according to the following me- 

 thod, as we wished to determine the amount of phosphoric 

 acid. After the loss had been determined by heating to red- 

 ness, the powder was mixed in a beaker with a solution of 

 sulphate of ammonia and hydrosulphate of ammonia. In this 

 manner the whole of the molybdenum and phosphoric acid 

 were obtained in solution of a dark brown colour, and the 

 sulphate of baryta could be collected on a filter and easily 

 washed. The filtered solution was mixed with mrriatic acid, 

 the sulphuret of molybdenum collected on a filter, and the 

 liquid evaporated : this contained the phosphoric acid ; it was 

 first mixed with an excess of ammonia and then with sulphate 

 of magnesia, and the precipitated phosphate of magnesia col- 

 lected upon a filter after having stood for 24 hours, washed 

 with water containing ammonia, dried, ignited and weighed. 

 0-937 grm. salt lost on ignilion 0*015, and gave 0*7279 sul- 

 phate of baryta =* 0*4736 baryta and 0*016 phosphate of mag- 

 nesia = 00102 phosphoric acid. 



The salt dried at 2 1 2° consequently contains in 100 parts — 



1. II. 



Baryta 50-074 50*543 



Oxide of ammonium . . 1833 1*601 



Molybdicacid \ , R , nQ „ 46*769 



Phosphoric acid J ' * ** UyJ 1*087 



