434 On the Atomic Weight of Molybdenum. 



chloride of ammonium, and treating the residue with a few 

 drops of nitric acid ; but this determination is far more un- 

 certain than in the case of the lead salt, as a considerable 

 quantity of molybdenum is volatilized in the form of some 

 chlorine-compound, which was very perceptible, from the pa- 

 per covering the beaker being coloured blue. 



Analysis.— 0'24>31 grm. of salt gave 0*1862 chloride of sil- 

 ver = 0*1505 oxide of silver. The evaporated liquid afforded 

 0*051 molybdic acid, corresponding to 20*971 per cent., so 

 that, compared with the theoretical composition, we expe- 

 rienced a loss of 17*2 per cent, of molybdic acid. 



The following is the composition in 100 parts: — 



a. Ca!c. 6. Calc. Found. 



1 at. Oxide of silver 1449-660 61*988 1449*660 62 338 61*929 

 1 at. Molybdic acid 888*966 38*012 875*829 37*662 



2338*626 100000 2325*489 100000 



Acid Molybdate of Silver. — When a solution of the trimo- 

 lybdate of potash is mixed with nitrate of silver, a flocculent 

 white precipitate is immediately produced. If this is collected 

 upon a filter and well washed, although a portion is dissolved, 

 various compounds appear to be obtained under different cir- 

 cumstances, as will be seen from the analyses. These salts 

 are anhydrous. 



Analysis. — I. 0*7694 grm. salt gave 0*3783 chloride of sil- 

 ver = 0*305 oxide of silver. 



II*. 0*8353 grm. gave 0*4195 chloride of silver = 0*3392 

 oxide of silver. 



III. 1*025 grm. gave 0*5148 chloride of silver = 0*4162 

 oxide of silver. 



IV. 2*0109 grms. salt gave 1*0235 chloride of silver = 0*8274 

 oxide of silver. 



Or, in 100 parts, — 



I. II. HI. IV. 



Oxide of silver 39*754 40*605 40*608 41*143 



These numbers agree best with the formula AgO, 3Mo0 3 

 + AgO, 2Mo0 3 :— 



a. Calc. b. Calc. 



2 at. Oxide of silver 2899*320 39*478 2899*320 39*384- 



5 at. Molybdic acid 4444*830 60*522 4379*145 60*166 



7344*150 100*000 7278*465 100*000 

 [To be continued.] 



* The salt employed for the analyses II. and III. was taken from the same 

 portion. 



