446 NITROGEN. 



SEC. V. NITROGEN. 



COMBINATIONS OF NITROGEN AND PRECEDING SIMPLE BODIES. 

 COMPOUNDS OF NITROGEN WITH OXYGEN, AND THE COMBINA- 

 TIONS OF THESE WITH PRECEDING BODIES. 



Remarks. As it seemed difficult to advance at all without a 

 knowledge of the composition of the atmosphere, the history of nitro- 

 gen was given in connexion with that subject. It now remains to 

 detail the history of the other Compounds into which nitrogen enters, 

 in connexion with oxygen, and it seeins to me that the properties 

 of this very singular class of bodies will be best understood by taking 

 them in the following order. 



NITRIC ACID. -NiTRic OXIDE GAS, (nitrous gets.) NITROUS 

 ACIDS. NITRATES OF ALKALIES. NITROUS OXIDE, (exhilirating 

 gas.) NITRATES OF EARTHS. NITRITES ; to be concluded by a 

 recapitulation of the composition, fyc. of the nitric compounds. 



NITRIC ACID. 



1. HISTORY. First obtained by distilling a mixture of nitre and 

 clay. The discoverer was Raymond Lully, a chemist of the island 

 of Majorca, born in 1235. Basil Valentine, in the fifteenth century, 

 describes the process more minutely, and calls the acid water of nitre ; 

 subsequently it was called spirits of nitre and aquafortis ; the latter 

 is still the name in the shops. Called nitric acid by the French 

 chemists, in 1782; because it is obtained from nitre.* On the prin- 

 ciples of the nomenclature, it would, at that time, have been called 

 azotic acid, and the name azote was altered to nitrogen to make the 

 terminology consistent. 



2. PREPARATION. 



(a.) For information merely, the original experiment of Mr. Cav- 

 endish may be repeated. f In that case, it was formed by electrizing 

 for a great length of time, with many thousand shocks, a mixture of 

 oxygen and nitrogen gases, in the proportion, by measure, of 5 parts 

 of oxygen to 3 of common air, or 7 oxygen to 3 nitrogen, or common 

 air by itself. J It may be done, over quicksilver, in a glass tube, 

 furnished with gold or platinum wires ; caustic potash, introduced 

 before electrization, will absorb the acid as it is formed, and thus 



* Familiarly called saltpetre. 



t See Phil. Trans. Vol. LXXV, 1785. 



' t Oxygen and azotic gas were mixed by Mr. Cavendish, in the proportion of 416 

 of the former, to 914 of the latter, in bulk, in one experiment, and in another, in the 

 proportion of 1920 : 4860, and (Phil. Trans. 1785,) he converted them totally into 



WITRIC ACID. 



A distinguished chemist, in London, informed me, in 1805, that he and a noble- 

 man who was his pupil, had labored during a month to produce nitric acid by the ori- 

 ginal experiment of Mr. Cavendish^ but without success. This goes only to prove 

 that it is a difficult process, for the name of Mr. Cavendish is sufficient authority for 

 any thing which he asserts. 



