430 MM. Svanberg and Struve on the Atomic Weight 



with an excess of ammonia, and then so much chloride of ba- 

 rium added that a portion of the salt of ammonia was left un- 

 decomposed. It was immediately collected upon a filter, 

 access of air being prevented as much as possible. 



This salt forms a fine crystalline powder, which is anhydrous 

 and sparingly soluble in water; on calcination it acquires a 

 bluish-green colour, owing to the reducing action of the traces 

 of ammonia which escape. It does not fuse ; adheres very 

 firmly to the glass. 



Analysis. — I. 0*864 grm. of salt obtained by method I. lost 

 on ignition 0*014, and gave 0*634 sulphate of baryta = 0*4262 

 baryta. 



II. 1*686 grm. salt, according to method II. , lost on ignition 

 0*0273, and gave 1*2982 sulphate of baryta = 0*846 baryta. 



Assuming the loss by ignition to consist of ammonia, 100 

 parts of the salt contain — 



I. II. 



Baryta 49*323 50*177 



Oxide of ammonium . 1*620 1*619 



Molybdic acid . . . 49*057 48*204 



and the ignited salt — 



Baryta 50*137 51*003 



Molybdic acid . . . 49*863 48*997 



Although these analyses do not agree accurately in the 

 amount of baryta, we mention them because they show that a 

 certain amount of the oxide of ammonium salt always accom- 

 panies them. The loss by ignition does not result either from hy- 

 grometric or chemically combined water, as we have convinced 

 ourselves of the presence of ammonia, not by quantitative but 

 by qualitative experiments. Were we to attempt to deduce a 

 formula from these numbers, we should find that 1 at. of the am- 

 monia salt is combined with about 12 ats. of the salt of baryta. 

 The composition of the neutral molybdate of baryta, according 

 to theory, is — 



a. Calc. b. Calc. 



1 at. Baryta . . 955*29 51*789 955*29 52*17 

 1 at. Molybdic acid 888*966 48*202 875*829 47*83 



1844*256 100*000 1831*119 100*00 



Heine* has described a basic molybdate of baryta, of which 

 he gives two analyses, which however were made with the 

 same preparation. On comparing the characters which he 

 gives of his salt with those of our neutral molybdate of baryta, 

 they agree very accurately. We have also endeavoured to 

 prepare the basic salt according to Heine's description, but 

 * Journ.fur Prakt. Chem. 1836. vol. ix. p. 204. 



