Researches on the Salts of Selenious Acid. 



79 



2. Neutral: AP.OISeO -f 7H 2 0. 



In order to obtain this, the preceding salt was treated with the 

 necessary quantity of selenious acid, viz. 16.20 pr. ct. selenious anhydride. 

 The acid being allowed to act upon it for some time, the product was cry- 

 stalline; as the mother-liquor reacted strongly sour and was precipitated by 

 ammonia the salt is soluble in water, though very sparingly. 



Analyses: 



1) 0.5135 gr. salt gave 0.213 gr. selenium or 0.2993 gr. selonious acid 

 and 0.0934 gr. alumina. 



2) 0.585 gr. salt gave 0.243 gr. selenium or 0.3414 gr. selenious acid and 

 0. 106 gr. alumina. 



3) 0.4935 gr- salt lost at 100° 0.017 gr. water. 



Represented in 100 parts: 



found calculated 



1. 2. 3. 



Alumina 18.19 18.12 — APO 2 103 18.33 



Selenious acid .. 58.28 58.36 — 2Se0 2 333 59.25 



Water (loss). . . . 23.53 23.52 3.45 7H 2 126 22.42 



100.00 100.00 562 100.00 



Muspratt's analytical determinations do not agree with this compo- 

 sition of the neutral selenite of aluminium. 



In salt containing water, dried over sulphuric acid, he has found 

 10.71 pr. ct. of water, leading to the formula AP.O'\3SeO + 3H 2 0, without, 

 however, more closely specifying how he arrived at this number; besides he 

 adduces amounts of alumina and selenious acid, the latter as a loss, in a 

 waterfree neutral salt, but leaves the reader wholly ignorant how he has 

 obtained this compound. Regarding the preparation of the salt — it was 

 obtained from alum with selenite of alkali — he says that "great care must 

 be taken that the precipitant is neutral", but what precautions he himself 

 took he has not communicated. 



3. Sespuiselenite : 2[AP.O i; .3SeO] + 3H 2 .0 2 .SeO + 9H 2 0. 



3 / 4 -selcnite of aluminium was treated in water with 81.02 pr. ct. its 

 weight of selenious anhydride or precisely the quantity necessary to form 



