232 Intelligence and Miscellaneous Articles. 



pages, and an extract appears in the Journal de Pharmacie, third 

 series, vol. ii. p. 179. M. Gay-Lussac states that the principal fact 

 arising from the researches of M. Millon is the following : — 



If to nitric acid which is too weak to act upon metals (copper 

 for example), or of density 1*07, a little nitrate of potash or hypo- 

 nitric acid be added, action immediately commences by the hypo- 

 nitric acid which oxidizes and dissolves the copper ; immediately 

 afterwards the nitric acid seizes the oxide of copper and sets the 

 hyponitric acid at liberty ; but this attacking the copper, produces 

 deutoxide of azote, which, with the nitric acid, reproduces a fresh 

 quantity of hyponitric acid, &c. &c. ; so that the nitric acid, which is 

 quite inactive with regard to metallic copper, confines its action to 

 dissolving the oxide of copper and the continual reproduction of 

 hyponitric acid. In a word, the action commenced by the hyponitric 

 acid continues and is propagated in the manner of a fermentation ; 

 pure nitric acid does not attack metals, and when it appears to 

 attack them, it is to the nitrous acid which it contains that the ac- 

 tion is due. 



In order to ascertain whether circumstances were such as they are 

 described by M. Millon, M. Gay-Lussac performed the following ex- 

 periment : — He prepared at first nitric acid of density l - 07, like that 

 employed by M. Millon ; but having found that it readily attacked 

 copper shavings at a temperature of about 57° Fahrenheit, it was 

 gradually diluted down to 1*02, previously to which it acted upon 

 copper, but was then inactive. Some concentrated sulphuric acid 

 was then diluted with eight or nine times its volume of water ; equal 

 quantities of copper shavings were then put into two glass tubes of 

 the same diameter, and to one of them was added inactive nitric 

 acid, and to the other an equal volume of diluted sulphuric acid. 

 The two tubes were immediately placed, touching each other, in cold 

 water, to keep the temperature equal in them both, The two acids 

 appeared quite inactive with regard to the copper, and to each of 

 them was added a small and the same quantity of hyponitric acid, 

 and the copper was immediately attacked in both tubes with remark- 

 able activity ; the two liquids appeared opake and frothy, on account 

 of the great number of small bubbles which were disengaged. The 

 action continued for several hours, and appeared to be always as 

 strong with the sulphuric acid as with the hyponitric [nitric ?] . The 

 quantities of copper dissolved were also nearly equal. 



This experiment M. Gay-Lussac is of opinion is not very favour- 

 able to M. Millon's theory, and at any rate it requires explanation. 

 He is of opinion that it merely proves that hyponifrous or nitrous acid, 

 whichever it may be called, is less stable than nitric acid ; that even 

 when much diluted, it oxidizes copper and many other metals, which 

 are afterwards dissolved by acids perfectly inactive as oxidizers. 

 Unquestionably, on account of the great instability of hyponitric 

 acid, it will be readily conceived that when it exists in nitric acid, it 

 will be first decomposed ; but M. Millon's opinion can hardly be ad- 

 mitted, that nitric acid is by itself inactive, and only becomes active 

 on account of the presence of a small quantity of nitrous acid, which 



