958 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



but has been converted into fat. 1 Similar results are characteristic of arsenic 

 and antimony poisoning, and of yellow atrophy of the liver. 



Detection. If any organ containing phosphorus be boiled with water in a flask with a 

 long upright tube, a ring of luminous phosphorus will condense at a certain point of 

 the tube. 



Compounds of Phosphorus with Oxygen. Of these compounds three 

 oxides and several acids exist, but only meta- and orthophosphoric acid need 

 attention here. 



Phosphorus Peroxide, P 2 O 5 , is a white powder, which rapidly absorbs 

 moisture ; it is produced by burning phosphorus in dry air. 



Metaphosphoric Acid, HPO 3 , is said to occur combined in nuclein. 



Preparation. (1) By dissolving P 2 O 5 in cold water, 



= 2HP0 3 . 



(2) By fusing phosphoric acid, 



It is converted slowly in the cold, rapidly on heating, into phosphoric acid. 

 Crystalline it forms ordinary glacial phosphoric acid. Metaphosphoric acid 

 precipitates proteid from solution, yielding a body having the properties of 

 nuclein, 2 but this has been denied. 3 



Orthophosphoric Acid, H 3 PO 4 . Salts of this acid constitute all the in- 

 organic compounds of phosphorus in the body, and are called phosphates. 



Preparation. (1) By heating solutions 9f metaphosphoric acid, 



(2) By treating bone-ash with sulphuric acid, 



Ca 3 (PO 4 ) 2 + 3H 2 S0 4 = 3CaS0 4 + 2H 3 PO 4 . 



Properties. On evaporation of the liquors obtained above, the acid separates in color- 

 less hygroscopic crystals. 



Phosphoric acid forms different salts according as one, two, or three atoms of hydrogen 

 are supplanted by a metal. Thus there exist primary sodium or calcium phosphates, 



rr -pf\ 



NaH 2 P0 4 and Ca<g 2 pQ 4 ; the secondary phosphates, Na^HPO* and CaHP0 4 ; and the 



tertiary phosphates, Na 3 P0 4 and Ca 3 (P0 4 ) 2 . On account of their reaction to litmus 

 these salts have been falsely called acid, neutral, and basic, but the secondary salts are, 

 chemically speaking, acid salts. 



The bones contain a large quantity of tertiary phosphate of calcium ; the 

 fluids and cells of the body contain likewise the primary and secondary phos- 

 phates, while to primary sodium phosphate carnivorous urine mainly owes its 

 acid reaction. 



In speaking of the ash of protoplasm, Nencki 4 advocates the idea of separate 

 combinations of the base and acid radicles with the proteid molecule, as, for 



1 J. Bauer: Zeitschrift fur Biologic, 1871, Bd. 7, p. 63. 



a L. Liebermann : Berichte der deutschen chemlwhen Gesellschaft, Bd. 22, p. 598. 



3 Salkowski : Pfliiger's Archiv, 1094, Bd. 59, p. 245. 



* Archiv filr exper. Pathologic und Pharmakologie, 1894, Bd. 34, p. 334. 



