Researches on the Salts of Selenious Acid. 117 



23 mol. of water, out of the 27 that the salt contains, are carried 

 off at 100° (calc. 21.78 p. ct.). 



2. Neutral: Sn.0 4 .2SeO. 



This salt was obtained by digesting the basic salt with 4 mol. sele- 

 nious acid at about 60° and evaporating the solution, when it formed a 

 microscopically crystalline residue, insoluble in water. It is dissolved in 

 hydrochloric acid, but only when the acid is warm and in considerable 

 excess in which it exhibits a complete analogy with selenite of zirconium. 

 On account of this, the analyses present a very considerable loss of sele- 

 nious acid. As the salt proved to be waterfree, however, the assumed 

 composition is by no means doubtful. 



An alyses: 



1) 0.44 gr. salt, when heated, gave 0.176 gr. dioxide of tin. 



2) 0.4465 gr. salt gave, after heating, 0.1765 gr. dioxide of tin. 



3) 0.5175 gr. salt gave 0.2085 gr. selenium or 0.2929 gr. selenious acid. 



4) 0.5905 gr. salt gave 0.244 gr. selenium or 0.3428 gr. selenious acid. 



Calculated on 100 parts: 



found calculated 



1. 2. 3. 4. 

 Oxide of tin. . . 40.00 39.53 — — SnO 2 150 40.32 

 Selenious acid. . — — 56.62 58.05 2Se0 2 222 59.68 



372 100.00 



When the above-mentioned basic salt was digested with respectively 

 14 and 34 mol. selenious acid, under circumstances, consequently, when 

 diselenites and tetraselenites could have been formed, the residue, after 

 evaporation to dryness and treating with water, presented so viscid a 

 consistency, that it could not be obtained in a fit state for analysis. 

 Subjected to the microscope, its appearance proved to be completely the 

 same as that of the above described neutral selenite, from which it may 

 with tolerable certainty be inferred that dioxide of tin, in complete analogy 

 with zirconia, affords no acid selenite. 



Of the quadrivalent elements, the selenites of which have been here 

 examined, zirconium and tin consequently show a correspondence, whereas 

 thorium here, as in other cases, in its acid salts is single in its kind. 



