Researches on the Salts of Selenious Acid. 



41 



SELENITES OF LEAD. 



1. Neutral: Pb.CHSeO. 



Acetate of lead being precipitated with selenite of sodium, a heavy, 

 crystalline precipitate was obtained which, under the microscope, proved to 

 be composed of small prisms. Almost insoluble in water, the salt is easily 

 dissolved by warm, dilute hydrochloric acid. 



Analyses: 



1) 0.6915 gr. salt, fumed with sulphuric acid, gave 0.63 gr. sulphate of 

 lead or 0.4636 gr. oxide of lead. 



2) 0.516 gr. salt gave in the same way 0.47 gr. sulphate or 0.3459 gr. 

 oxide of lead. 



3) 0.6905 gr. salt was dissolved in dilute hydrochloric acid and precipita- 

 ted with sulphurous acid; the selenium obtained, being washed with 

 warm hydrochloric acid and then with water, weighed O.159 gr. = 0.2234 

 gr. selenious acid. 



4) 0.53 gr. gave after the same treatment 0.1235 gr. selenium or 0.1735 

 gr. selenious acid. 



Calculated on 100 parts: 



experiment theory 



1. 2. 3. 4. 

 Oxide of lead. . . 67.04 67.04 — — PbO 223 66.77 

 Selenious acid . . — — 32.35 32.74 SeO 2 111 33.23 



334 100.00 



Berzelius, by fuming with sulphuric acid, found in the salt 66.67 

 pr. ct. oxide of lead. 



Already on very gentle heating, this salt has a tendency to fuse, 

 and at a commencing dull red-heat it is complety fused, forming a dark- 

 yellow liquid, which on cooling solidifies to a yellowish white, radiately 

 crystalline mass, not, however, without some loss of selenious acid, amount- 

 ing, in one experiment, to 4.25 pr. ct. or precisely 1 / B of the acid contained 

 in the salt. At a low red heat, considerable quantities sublime; thus, after 

 half-an-hour's heating, a loss of 21.31 pr. ct. more was observed, so that 

 the salt had now parted with nearly 3 / 4 of its acid. The rest, being then 

 heated in the full flame of a Bunsen's gas-lamp diminished still more in 

 weight, the total loss amounting to 39.15 pr. ct. The residue was dissolved 



Nova Acta Re?. Soc. Sc. Ups. Ser III. 6 



