474 Sir B. C. Brodie on the Action of Electricity on Gases. [June 20, 



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 decom- 

 position 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, poly- 

 sulphide 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 inconsiderable 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 experiments alone, without introducing any hypothetical consider- 

 ations 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 chemical 

 theory is 2, with which theory, therefore, the experiments agree. 



The action of the gas upon a strongly alkaline solution of hyposulphite 

 of soda is precisely of the same character. The volume of gas was mea- 

 sured 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 ex- 

 periments 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 slightly alkaline hyposulphite of soda, with oil of turpentine, and with 

 protochloride of tin. 



The experiments with neutral and slightly alkaline hyposulphite of soda 

 were conducted precisely in the same manner as the experiments described 

 in Section III., with the strongly alkaline hyposulphite. The result, how- 

 ever, is very different, the contraction in this case being equal in amount 

 to twice the "titre" of the gas. The mean of 17 experiments made with 

 the neutral hyposulphite gave 2"02 as the value of this contraction, and 

 the mean of 10 experiments made with the slightly alkaline hyposulphite 

 gave for it the same value. 



It is hence to be inferred that the oxidation effected in these cases is 

 equal in amount to three times the oxidation effected by the same gas in 

 neutral iodide of potassium. 



