248 



s. HADA. 



easv to understand. It is prepared by mixinq; a solution of bismuth 

 nitrate, free from any unnecessary excess of nitric acid, with barium 

 or potassium hypophosphite, avoiding excess of the bismuth nitrate, in 

 which it is soluble. Vhe bismuth hypophosphite precipitates as a 

 white crystaJiine powder, slowly decomposed by its mother- liquor, and 

 soluble in bismuth nil rate solution. Filtered otf and dried on a 

 porous tile, it can be preserved for days unchanged. 



The analysis of this salt was carried out much in the same way as 

 that of the mercury salt, except that the bismuth sulphide was dissolved 

 in nitric acid and the solution precipitated by ammonium ciirbonate as 

 usual. Water was determined as loss in the vncuuni desiccator. In 

 the following table the calculation is for Bi(H2FU2)3,H20, which 

 therefore expresses the compqsition of the salt : — 



Calc. Found. 



I. II. 111. 



Bismuth 19-41 49*49 49-40 48-77 



Phosphorus 22-09 21-67 21-34 21-19 



Water 4-27 3-11 3-26 3-39 



Bismuth hvpophospViite decomposes very readily by heat, becom- 

 ing black and giving oif phosphine at temperatures only a little above 

 100°. At a stronger heat metallic globules and bismuth phosphate 

 are obtained. The globules washed with dilute hydrogen chloride to 

 clean.se them from adhering phosphate and then dissolved in nitric acid 

 prove to be metalli(^ bismuth free from phosphorus. As about two- 

 thirds of the bismuth is obtained as mt-tal, the decomposition of the 

 bismuth hypophosphite by heat may be expressed by the equation — 



3Bi(H2PO,)3 = :^Bi + Bi(P03)3 + 6P+90H, 

 This hvpophos{)hite is noticeable for yielding metal instead of phos- 

 phide, but this fact is in accordance with the experience of Berzelius 

 that bismuth phosphide fully decomposes when heated. 



