472 Royal Society : — 



of sodium, an increment occurs in the volume of the gas. Thus in 

 two experiments the increment in the vohime of the gas, as estimated 

 from the difference of the volumes in the pipette and the aspirator, 

 was 1*93, 1*99, the **titre" of the gas (as just explained) being taken 

 as 1 ; and the ratio of the sum of the oxygen lost by the binoxide of 

 sodium (as estimated by titration of the solution of binoxide of sodium 

 before and after the experiment with permanganic acid) and the 

 titre of the gas to the titre of the gas was in the same experiments 

 2*06, 2' 17. In two other experiments this same ratio was 2"00, 

 2*08, — the reaction being analogous to the decomposition of binoxide 

 of sodium by ferrocyanide of potassium, and of binoxide of hydrogen 

 by permanganic acid, previously investigated by the author. 



Section III. comprises an account of the action of the electrized gas 

 upon a solution of hydriodic acid, strongly alkaline hyposulphite of 

 soda, polysulphide of sodium, and other substances. 



In the case of the passage of the gas through a solution of hydriodic 

 acid, the oxidation effected (after a certain degree of concentration 

 of the acid has been attained) is exactly twice the oxidation effected 

 by the same gas in a solution of the neutral iodide of potassium. 

 The mean of 33 such experiments gave 1*99 as the amount of oxygen 

 employed in the oxidation of the hydriodic acid as compared with the 

 "titre" of the gas. The individual experiments exhibit no inconsi- 

 derable differences ; but the probable error of the result, as estimated 

 by the method of least squares, is 0*02 ; that is to say, from these expe- 

 riments alone, without introducing any hypothetical considerations 

 whatever, it is an equal chance that the true value of the ratio sought 

 lies between the values 2-01 and 1'97. The value indicated by che- 

 mical theory is 2, with which theory, therefore, the experiments 

 agree. 



The action of the gas upon a strongly alkaline solution of hypo- 

 sulphite of soda is precisely of the same character. The volume of 

 gas was measured before and after the experiment ; and a contraction 

 was found to occur equal in amount to the "titre" of the gas. The 

 mean of twenty-two experiments gave 1 '03 as the amount of this 

 contraction. The peculiar oxidizing properties of the ozone are 

 entirely destroyed by its passage through the solution ; and it is 

 to be inferred that while the diminution in volume is equal to the 

 "titre" of the gas, the oxidation effected in this, as in the previous 

 case, is the same as that which would be effected by a volume of oxygen 

 equal to twice the "titre" of the gas. 



Experiments made with a solution of polysulphide of barium gave 

 a similar result. 



Section IV. comprises various experiments made with solutions of 

 neutral and sHghtly alkaline hyposulphite of soda, with oil of tur- 

 pentine, and with protochloride of tin. 



The experiments with neutral and slightly alkaline hyposulphite 

 of soda were conducted precisely in the same manner as the experi- 

 ments described in Section III. with the strongly alkaline hyposul- 

 phite. The result, however, is very different, the contraction in this 

 case being equal in amount to twice the "titre" of the gas. The 



