496 



last described, was mixed with water and neutralized by an excess of 

 pure carbonate of potassium prepared from the tartrate. Acetic acid 

 was then added to the acid reaction, and the whole evaporated to 

 dryness on the water-bath. Treated with absolute alcohol, the in- 

 soluble* perchlorate was thrown upon a weighed filter, and com- 

 pletely freed from soluble acetate by washing with absolute alcohol. 

 The weight of perchlorate of potassium obtained was 1*080 grm. ; 

 hence the liquid contained 07837 grm. of C1O 4 H, or 99'93 per cent. 

 Of this potassium-salt, 0*9915 grm. lost, on heating in a long test-tube 

 with pure peroxide of iron, 0*457 grm. ; and the chlorine in the re- 

 sidual chloride of potassium required 0*7683 grm. of pure silver for 

 complete precipitation. 



Analysis No. 2. A portion of acid prepared on another occasion 

 gave the following results. Weight of acid taken 1*2185 grm.; 

 weight of dry potassium-salt obtained 1*6785 grm. : of this salt 

 0*9660 grm., heated with peroxide of iron, lost 0*4440 grm., and 

 the residual chloride required 7440 grm. of pure silver for com- 

 plete precipitation. 0*3165 grin, of the same perchlorate yielded, 

 on treatment with strong sulphuric acid, 0*2010 grm. of sulphate 

 of potassium. Hence the liquid contained 1*2179 grm., or 99*95 

 per cent, of C1O 4 H. 



Analysis No. 3. 0*3155 grm. of pure acid was diluted with water 

 and treated with an excess of freshly precipitated carbonate of barium. 

 On filtering and washing, the barium in the filtrate was estimated as 

 sulphate, of which salt 0*3660 grm. was obtained, showing that 

 the substance contained 0*3157 grm., or 100*06 per cent, of 

 CIO, II. 



Composition of Potassium- Salt obtained from add. 



Found. 



138*5 100-00 100*12 



* It was found that 2 grms. of pure perchlorate of potassium, after washing 

 with 100 cub. cent, of absolute alcohol containing a trace of acetate in solution, 

 and then with 50 cub. cent, of pure alcohol, lost T R y of a milligramme. 



