416 MM. Svanberg and Struve on the Atomic Weight 



clifies into a crystalline mass as soon as the temperature is a 

 little lowered. When it has become cold it falls to a white 

 powder. This peculiarity is very striking, and merits every 

 attention. The salt deliquesces when exposed for any length 

 of time to the air, greedily absorbs carbonic acid, and gra- 

 dually passes into other salts. Although insoluble in alcohol, 

 it is only separated in the form of an oil by alcohol from the 

 most concentrated solution in water. 



Analysis. — I. Salt obtained according to the method A. 

 0*2179 grm. gave after ignition 0*1825 sulphate of potash, or 

 0*0986 potash. 



II. Salt prepared according to the method B. 1*500 grm. 

 lost on ignition 0*043 and yielded 0*844- sulphate of potash 

 = 0*456 potash. 



III. The same salt as in II. 0*7793 grm. anhydrous salt 

 gave 0*587 sulphate of potash = 0*317 potash. 



According to analysis II. the crystalline salt contains in 

 100 parts — 



Potash 39*663 



Molybdic acid . . . 56*598 

 Water .-..». 3*739 



100 parts of the anhydrous salt contain — 



I.* IT. III. 



Potash . . . 45*363 41*203 40*707 



Molybdic acid 54*637 58*797 59*293 



The calculated theoretical composition of the crystalline 

 salt is — 



Atomic Calcu- Atomic Calcu- 



weight, a\. latecl. weight, b. lated. 



1 at. Potash . . . 588*856 38*385 588*856 38-717 



1 at. Molybdic acid 888*966 57*949 875*829 57*585 



\ at. Water . . . 56*239 3*666 56*239 3*698 



1534*061 100*000 1520*924 100*000 

 The theoretical composition of the anhydrous salt is — 



a. Calculated. b. Calculated. 



I at. Potash . . . 588*856 39*840 588*856 40*204 

 1 at. Molybdic acid 888-966 60*160 875*829 59*796 



1477*822 100*000 1464*685 100*000 

 It will be seen on comparing the found quantities of potash 



* The excess of 5£ per cent, in this analysis is partly owing to the salt 

 having crystallized from a strongly alkaline solution, and partly to the mo- 

 lybdic acid not having been entirely freed from every trace of phosphoric 

 acid and alumina. 



t Throughout this paper we intend, by the designation atomic weight, a, 

 that the atomic weight of molybdenum is 588*966, and by b, the atomic 

 weight 575-829. 



