170 Goochand Osborne — Potassium Aluminium /Sulphate. 



From these experiments, in which approximately three times 

 the amounts of potassium bromide and potassium bromate, 

 corresponding to the complete hydrolysis of the alum, were 

 used, it is obvious that the hydrolysis is not complete. At the 

 end of an hour nearly five-sixths of the acidic ion have been 

 liberated and this proportion is not much exceeded after four 

 hours boiling, the liberation of bromine proceeding very slowly 

 during the greater part of this time. 



In the following series of determinations the proportions of 

 potassium bromide and potassium bromate with reference to 

 one another and to the aluminium salt were varied in order to 

 test the effect of such variation on the course of the action. 



(0 



(2) 

 (3) 

 (4) 

 (5) 

 (6) 



Table III. 

 A 

 Theory 6Br to 2KA1(S0 4 ) 3 .12H 3 0. 



Time 

 hrs. 



3 

 3 

 3 

 3 

 3 

 4 



KA1(S0 4 ) 2 12H 2 KBr 



taken 

 grm. 



0-5000 

 O'oOOO 

 0-5000 

 0-5000 

 0-5000 

 0-5000 

 0-5000 



taken 

 grm. 



^0-32 

 3-2 

 0-32 

 3-2 

 6- 

 6- 

 6- 



KBr0 3 

 taken 

 grm. 



09 

 09 



*0 

 

 

 

 2 

 2 

 2 



90 

 90 



Theory for 



bromine 



grm. 



0-2527 

 0-2527 

 0-2527 

 0-2527 

 0-2527 

 0-2527 

 0-2527 



Bromine 

 found 

 grm. 



0-1437 

 0-1814 

 0-1853 

 2182 

 0-2199 

 0-2229 

 0-2320 



Error in 



terms of 



bromine 



grm. 



0-1090— 

 0-0713— 

 0-0674— 

 0-0345 — 

 0-0328— 

 0-0298— 

 0*1)207 — 



Error in 

 term 8 of 



A1 2 0, 



grm. 



0-0232— 

 0-0152— 

 0-0144— 

 0-0073— 

 0-0069— 

 0-0063— 

 0-0044— 



B 



Theory 5Br to 2KA1(S0 4 ),.12H 2 0. 



(1) 



3 



0-5000 



*0'32 



*0-09 



0-2106 



0-1437 



0-0669- 



0-0143— 



( 2 ) 



3 



0-5000 



3-20 



0-09 



0-2106 



0-1814 



0-0292 — 



0-0062— 



( 3 ) 



3 



0-5000 



0-32 



0-90 



0-2106 



0-1853 



0-0252 + 



0-0054 — 



( 4 ) 



3 



0-5000 



3-2 



0-90 



0-2106 



0-2182 



0-0076 + 



0-0016 + 



(5) 



3 



0-5000 



6- 



2' 



0-2106 



0-2199 



0-0090 + 



0-0019 + 



(6) 



4 



0-5000 



6- 



2* 



0-2106 



0-2229 



0-0123 + 



0-0026 + 



(7) 



5 



0-5000 



6- 



2- 



0-2106 



0-2320 



0-0214 + 



0-0045 + 



In the result of experiment (1), in which the amounts of 

 bromide and bromate were equivalent to one another and to 

 the acidic ion of the aluminium salt, it will be noted that the 

 liberation of the bromine falls considerably short of five-sixths 



* These amounts are nearly equivalent to the acidic ion of the aluminium 

 salt. 



