46 



L. F. Nilson, 



Calculated on 100 parts: 



theory 



Magnesia 11.06 11.07 



Selenious acid . . 82.02 82.16 

 Water (loss). . . . 6.92 6.77 



MgO 40 9.78 

 3Se0 2 333 81.42 

 2H 2 36 8.80 



100.00 100.00 



409 100.00 



The values obtained indicate that the salt has been in some measure 

 impure with an anhydrous salt, which, under the circumstances under which 

 the crystallization took place, might easily have been formed. Thus is 

 explained the slight excess, that the analysis presents, both of base and 

 acid, as compared with the calculated values. 



Instead of a tetraselenite, magnesium consequently forms a triselenite, 

 and the former seem no way possible to be obtained. In the following, 

 when accounting for the salts of glucinum and cobalt, we shall find com- 

 pounds, analogous to this salt, and also formed under similar circumstances. 



Berzelius, respecting these compounds, only mentions that "selenite 

 of glucinum is a white powder: the biselenite is soluble and dries, when 

 evaporated to a gummy mass, which cracks of itself. Both of them lose 

 acid on heating". Muspratt says no more than : "This selenite is, in every 

 way, analogous to that of alumina", without communicating any reasons 

 for the statement, and; "the biselenite is extremely soluble and does not 

 crystallize". 



The only selenites of glucinum examined respecting their composi- 

 tion, that are known, have been described by Atterberg 1 ). He obtained 

 namely three basic salts of the following composition: 



') Svenska Vetensk. Akad.s handl. 1873 N:o 5 and Bull, de la Soc. chim. de 

 Paris XXI. p. 157. (1874). 



SELENITES OF GLUCINUM. 



Be 3 .0 5 .2SeO + 6H 2 

 Be 2 .0 3 .SeO + 4H 2 

 Be 7 .O 10 3SeO + 14H 2 O. 



