306 Gooch and Danner — Points in the Interaction of 



Table III. 



H-S0 4 [1 : 1] = 50 per cent 

 Time Gas from 

 100 cm 



elapsed. 



5 min. 



1 hour. 



1 day. 



3 days. 



4 " 



15 



17 

 35 



0-1 



l-l 



14- 



15 3 



15-6 



16 



17-3 



17-4 

 17 5 



Appearance. 



No change. 

 No change. 

 Red brown. 

 Light brown. 



Brown, turbid. 

 \ Clearing by precipi- 

 1 tation. 



Clear, straw-colored. 



H 2 S0 4 [1 : 1] = 25 percent. 

 Gas from 

 100 cm 3 . Appearance. 



Small bubble. No change. 



9-6 cm 3 

 15-1 " 



18 

 18-4 " 



1 hour. 



I day. 



3 days. 

 14 " 

 37 " 

 44 " 



C. 

 H 2 S0 4 [1 : 1] = 12-5 per cent. 



No change. 



Small bubble. 

 Bubble. 

 Bubble larger. 

 7-1 cm 3 



11- " 



12- " 



Color lighter. 



| Reddish purple. 



I Turbid. 

 Reddish pink. 

 Clearing by pre- 

 cipitation. 

 Nearly clear. 



j Clear and color- 

 f less. 



D. 

 H 2 S0 4 [1 : 1] = 6-25 per cent. 



Small bubble. No change. 

 Bubble. " 



Bubble larger. " " 



1 cm 3 " " 



3 " " " 



5 " Little change. 



The full amount of permauganate present in 100 cm 3 of 

 each mixture should, if reduced to the lowest condition of oxi- 

 dation, be capable of liberating about 28*6 cm 3 of oxygen, 

 and every cubic centimeter of gas collected corresponds to 

 3*5 per cent of the entire quantity of available oxygen. In 

 comparing the amount of gas liberated at once by 50 per cent 

 sulphuric acid [1 : 1] (Table III, A) with the amount of reduc- 

 tion of the permanganate indicated under similar conditions 

 (Table I, A) it appears that less than one-fifth (0 - 35 per cent) 

 of the available oxygen of the permanganate which disap- 

 pears in the action escapes solution and appears in free form. 

 When, however, the comparison is made between the amount 

 of gas liberated after four or five days (about 55 per cent of 

 the total available oxygen) and the amount of reduction of 

 the permanganate during a similar interval (Table I, C) the 

 agreement is fairly close — within one or two per cent — the 

 proportion of oxygen which goes to saturate the liquid being 

 small relatively to the large absolute amount. It would seem 

 to be evident that during this interval the breaking up of the 

 permanganate resulted chiefly in its reduction to the lowest 

 form of oxidation. After the seventh day in Exp. A, when 

 a precipitate began to appear, comparatively little oxygen was 

 set free ; and on the thirty-fifth day, when the precipitation 

 had ceased and the remaining liquid was straw-colored the 

 amount of gas collected corresponded to about 61 per cent of 



