130 SIE WILLIAM RAMSAY 



rough calculation that on adding my 60 c.c. of gas of sp. gr. 16 

 to the nitrogen from which it was obtained it would amount to 

 3 p.c. of the total, and that such a mixture of N = 4 with X= 16 

 would give a gas of the density you find. This is so far encour- 

 aging, but I must try to further purify the gas. I think that it 

 still contains some nitrogen, and moreover it will be none the 

 worse of another treatment with hot magnesium. 



Has it occurred to you that there is room for gaseous elements 

 at the end of the first column of the periodic table ? Thus, 



Li Be B C N F 

 jj jj >j 01 



Mn Fe Co Ni 

 Br 



? Pd Ru Rh 

 etc. 



Such elements should have the density 20 or thereabouts, and 

 0'8 p.c. ( = THhrkh about) of the nitrogen of the air would so 

 raise the density of nitrogen that it would stand to pure nitrogen 

 in the ratio 230 : 231." 



Later on, 4th August, iiH4; the letter is headed 

 Private : 



" I have isolated the gas. Its density is 19'075 and it is not 

 absorbed by magnesium. The last passage of the gas mixed 

 with nitrogen over red-hot magnesium eight or ten times yielded 

 only 3 milligrams of ammonium chloride from the magnesium 

 nitride formed. I think that there is some 1 p.c. in the nitrogen 

 of the air. . . . The nitrogen prepared from magnesium nitride 

 is chemical nitrogen, i.e. it has a density 1/230 below that from 

 air (your experiments). The value of the chemical N 2 is identical 

 with yours. I have been watching the density of X creep up as 

 absorption proceeds ; so you see this is no chance determination 

 with a possible source of error." 



