1892.] 



Formation and Decomposition of Nitrous Acid. 



33 





To decide between these views, and to determine the limit, 

 whether of nitrous acid formed or of nitric oxide dissolved, as the 

 case might be, a series of experiments were conducted in the follow- 

 ing manner. 



Nitric acid was passed through an apparatus consisting of (1) a 



> wash-bottle containing soda ; (*2) a set of Liebig's bulbs ; and (3) a 

 set of Geissler's bulbs both filled with nitric acid of the same con- 

 centration, the latter of which was used for the analytical deter- 

 minations ; and (4) a wash-bottle containing soda to prevent any 

 nitrous fumes, produced by the passage of the unaltered nitric oxide 

 into the air, from accidentally coming in contact with the acid experi- 

 mented upon. In these and succeeding experiments the apparatus 

 consisted wholly of glass, except for small pieces of rubber tubing 

 which served for connections ; these were frequently renewed. Before 

 the nitric oxide was passed, the whole apparatus was filled with 

 hydrogen, my previous experiments having shown that this gas, when 

 ready-made, does not reduce nitric acid, but even mechanically blows 

 off any slight impurity of nitrous acid. At the end of the operation 

 the Geissler's bulbs were quickly detached, and the acid blown out by 

 a rapid stream of carbonic acid. While the experiment was proceed- 

 ng the bulbs were kept in a water-bath, the temperature of which 

 was carefully regulated ; the passage of the nitric oxide was kept as 

 uniform as possible. 



The following table contains the results of the first set of experi- 

 ments ; not only of the actual amounts of nitric acid, and of nitrous 

 acid, i.e., the reducing power, are given, but also of the percentage 

 amounts of these acids, taking the total acidity as 100 : 



Series I. 

 Temperature, 22' 5. 



These results show that the phenomenon, whether of reaction or 

 of solution, was complete at the end of the first interval of time ; but, 

 taken by themselves, they would not suffice to distinguish under 

 which category the change is to be classified. Accordingly a series 

 of experiments were conducted in which the only variable condition 

 was that of temperature, for, as pointed out above, if the nitric oxide 



VOL. LII. D 



