CHAPTER XXVII 

 PHOSPHORUS, ARSENIC, ANTIMONY, BISMUTH 



WE now take up the elements which, with nitrogen, form the 

 nitrogen family. These elements all have two regular valences, 

 being trivalent and quinquivalent. Nitrogen, phosphorus and 

 arsenic are non-metallic elements, that is, they do not form posi- 

 tive radicals of salts. Antimony is non-metallic, although in 

 its trivalent condition it acts also as a metallic element. Bismuth 

 is metallic. 



PHOSPHORUS P 



Occurrence. Calcium phosphate Ca 3 (P0 4 ) 2 forms about 25 

 to 27 per cent of the material of the bones and teeth of animals. 

 The same salt occurs in deposits, as a mineral, and is found scat- 

 tered through all fertile soils. Complex organic compounds of 

 phosphorus, such as lecithin, are essential constituents of the 

 muscles, nerves and brains of animals and are found also in plants. 

 The average man's skeleton contains 1400 g. of phosphorus, his 

 muscles 130 g., and his nerves and brain 12 g. Amongst foods. 

 ggg-yolks and beans contain a.n imnsnallv large proportion, nuts, 

 peas, and wheat (entire grain) coming next. 



Phosphorus was discovered by Brand in 1669, and by Kunkel 

 in 1670, by distilling at a white heat the solid residue from evapo- 

 rated animal matter. They were both searching for the philoso- 

 phers' stone. Scheele in Sweden prepared it from bones in 1771. 

 The element is used chiefly in the manufacture of matches and, 

 to a small extent, in roach paste and rat poison. 



Manufacture of Pnospnorus. Phosphorus is now manu- 

 factured by mixing natural calcium phosphate with sand 



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