108 Mixter — Formation of Trisodium. Orthophospkate, etc. 



solutions of the fusions were tested adding silver nitrate and 

 then ammonia. No black substance remained, proving that an 

 antimonite was not present. The insoluble residues from the 

 fusions when treated with a boiling solution of potassium 

 hydroxide, silver nitrate and ammonia also yielded no black 

 substance. The insoluble residues mentioned even after long 

 digestion with water reacted alkaline, showing that the 

 hydrolysis of the sodium antimonate was not complete. 



The heat of formation of the oxides of antimony is derived 

 from the experimental results as follows : 



3Na o + 2Sb + 50 = 2Na 3 Sb0 4 + _.. 393*3 



SNajO + Sb 3 6 = 2Na 3 Sb0 4 + 163-7 



2Sb + 50 = Sb20s + 229-6 



2Na 2 2 -1- Na 2 + Sb 2 3 = 2Na 3 Sb0 4 + 191-5 



2Na 2 + 20 = 2Na a 3 + 38-8 



3Na 9 + Sb 2 3 + 20 = 2Na 3 Sb0 4 + . .. 230-3 



3Na 2 + Sb 2 6 = 2Na,Sb0 4 + ._. 163-7 



Sb20s + 20 = SbsOs + --- _ 66-6 



Na 2 2 + 2Na 2 + Sb 2 4 = 2Na,Sb0 4 + 164-1 



Na a O + O = Na 3 2 + ._. _ 19-4 



3Na 2 + Sb 2 4 + O = 2Na,Sb0 4 + 1835 



3Na 2 + Sb 2 5 = 2Na,Sb0 4 + __. 163-7 



Sb 2 04 + = SbsOs + --._ 19-8 



2Sb + 50 = Sb 2 5 + - 229-6 



Sb 2 4 + O = Sb 2 5 + _. 19-8 



2Sb + 40 = Sb>04 + 2098 



2Sb + 50 = Sb 2 5 + 229- 



Sb 2 3 + 20 = Sb 2 5 + _. 66- 



2Sb + 30 = Sb 2 3 + 1630 



Thomsen derived the heat of formation of antimonic acid 

 from that of the pentachloride and the heat effect of the hydro- 

 lysis of it and obtained Sb 2 , 6 , 3H 3 = 228*8 C , the writer 

 found that Sb 2 , 5 = 229*6 C . The difference between these 

 two numbers is within the limits of error. Thomsen stated 

 that the antimonic acid was free from chlorine and the writer 

 has also found that the hydrolysis of antimony pentachloride is 

 complete. Evidently the heat effect Sb 2 5 , 3IT 2 is quite 



