1858.] DAUBENY — AMMONIA FROM VOLCANOS. 297 



together in a highly condensed condition shall have been tried in an 

 unexceptionable manner. 



Perhaps indeed, if, as Professor Bischoff states, a mixture of the 

 two gases has been submitted to a pressure of 50 atmospheres 

 without combining, the question is not likely soon to be set at rest, 

 since it would not be easy to apply an artificial pressure equal to 

 that to which they would be subjected at the bottom of the ocean ; 

 where, at the depth of a mile and a quarter, the pressure is equal to 

 2809 lbs. to the square inch, or to at least 187 atmospheres*. 



Might not the experiment be tried by sending down to a great 

 depth in the ocean a vessel charged with a mixture of the two gases, 

 furnished with a piston, which should exert upon the contents a 

 pressure equal to that of the weight of water incumbent ? 



But the affinity which certain metals possess for nitrogen seems to 

 me to afford a more solid ground upon which to build a theory to 

 account for the fact before us. 



Not to speak of the simple combustibles, phosphorus and sulphur, 

 and the metalloids, potassium and sodium, which form combinations 

 with nitrogen, — zinc, copper, and iron may be instanced as bodies 

 capable of combining with it, — the nitride of the latter even dis- 

 engaging ammonia when heated in contact with water. 



As these combinations, however, require for their production the 

 previous formation of ammonia, through the medium of which 

 alone they are known to be brought about, they cannot be appealed 

 to as proving that the metal in question is capable of uniting with 

 gaseous nitrogen, and are only cited as indications that nitrogen 

 possesses a wider range of affinities than had formerly been attri- 

 buted to it. 



To meet the requirements of my hypothesis I must go a step 

 further, and appeal to the late researches, which, it seems, that 

 Wohler, in conjunction with M. H. Sainte-Claire Devillef, of Paris, 

 has instituted with regard to the metal titanium, undertaken with 

 a view of elucidating the discovery, which he had announced in 

 1849, concerning the combination which this body forms with ni- 

 trogen. Now, it appears from the recent researches of these two 

 chemists, reported upon in the * Comptes Rendus' for October 

 1857 (and which I now find detailed in a more extended form in 

 the 'Annales de Chimie' for the present month, January 1858), 

 that titanium absorbs nitrogen from the air, even in preference to 

 oxygen ; titanic acid being reduced at a high temperature whenever 

 air is admitted, and a nitride of titanium being formed in conse- 

 quence. Such indeed, it is stated, is the affinity of this metal for 

 nitrogen, that titanium can only be obtained pure by heating the 

 titanic acid in an atmosphere of pure hydrogen ; for if the opera- 

 tion be conducted in the presence of nitrogen, a nitride is sure to be 

 produced. The union, indeed, takes place with so much energy 

 as to generate light and heat, and thus to constitute a genuine case 



* The pressure of the atmosphere may be estimated at about 15 lbs. to the 

 square-inch; the pressure of the sea at 1£ mile is 187x15=2805. 

 f Ann. de Chimie, Jan. 1858, p. 61. 



