432 MM. Svanberg and Slruve on the Atomic Weight 



cipitate quickly forms, which appears under the microscope 

 to consist entirely of six-sided plates ; but this salt is not very 

 stable, it soon loses its bulky appearance, sinks and forms a 

 mixture of two salts, which may be distinguished by the mi- 

 croscope. One salt is amorphous, whilst the other crystal- 

 lizes in minute distinct six-sided prisms. Whether in this 

 case a similar decomposition occurs as with the potash salt, 

 we are unable to decide, and we have not made any fur- 

 ther experiments with it, as the mixture of salts cannot be 

 separated. 



The above salts were all prepared by double decomposition ; 

 another long series of baryta salts may be obtained by treating 

 any one of the former with nitric or muriatic acid. Various 

 acid salts are formed according to the amount of acid, some 

 of which are soluble, while others are perfectly insoluble. All 

 these compounds are remarkable on account of their being 

 crystalline. We have analysed only one of these salts. 



Molybdate of Baryta with 9 atoms of Acid, BaO, 9M0O 3 

 + 4HO. — We obtained this salt by treating the neutral salt 

 with nitric acid. It crystallizes in minute six-sided prisms. 

 This salt is insoluble in cold and in hot water, and in 

 dilute nitric acid. On ignition it parts with water, fuses, and 

 solidifies on cooling into a crystalline mass. As this salt is but 

 imperfectly acted upon by sulphuric acid or a mixture of sul- 

 phuric with nitro-muriatic acid, it was fused in a platinum 

 crucible with bisulphate of potash. 



Analysis. — 0782 grm. salt dried at 212° lost at a red heat 

 0-0393 water, and gave 0*120 sulphate of baryta = 0078 ba- 

 ryta, or in 100 parts — 



a. Calc. 6. Calc. Found. 



1 at. Baryta 955*290 10156 955290 10 256 9999 



9 at. Molybdic acid .. 8000*694 85*061 7882-461 84*900 84*975 

 4 at. Water 449-916 4*783 449*916 4*844 5*026 



9405*900 100*000 9287667 100*000 100000 

 The anhydrous salt has the following composition : — 



■ a. Calc. b. Calc. Found. 



1 at. Baryta 955*290 10*667 955*290 10*808 10*528 



9 at. Molybdic acid ... 8000-694 89*333 7882*461 89*192 89*472 



8955*984 100000 8837*751 100*000 100000 



Salts of Lead. 



Neutral Molybdate of Lead, PbO, MoO 3 .— Oxide of lead 

 does not appear to combine in more than one proportion 

 with molybdic acid; in all cases the neutral salt separates. 

 We prepared this salt by precipitating a solution of the tri- 



