22 A. P. VINOGRADOV 



TiN, has once been observed in the form of very small crystals in the Bustee 

 meteorite. The great rarity of these compounds does not exclude the possibility 

 that they might have been, in part at least, the sources of N2. On reacting with 

 water they yield NH4+. The process of emission of NH4CI and other ammonium 

 compoimds by volcanoes, and especially fumaroles, seems to be of greater extent. 

 It is sufficient to recall, as an example, the exhalations of Tuscany. In the loose 

 rocks of Kamchatka, a very long way from any volcanoes, we have found that 

 10-2 — 10 ~^ % of NH4CI is constantly present. In determining gases in 

 rocks Rayleigh [10] has shown that nitrogen may be present in them in a com- 

 bined state. According to recent determinations on igneous rocks, their nitrogen 

 content is about o-ooi cc/g of rock. That of stony meteorites is about o-ooo8 

 cc/g while it is interesting to record that the amount in duniies is minimal, i.e. 

 about 0-0004 cc/g. Is the NH4CI of volcanoes, then, a juvenile product, or is it 

 synthesized on the incandescent lava from the N2 of the air ? We have tried to 

 synthesize NH4CI on incandescent lava from H2 and N2 but the synthesis only 

 occurs in the absence of atmospheric O2. All this together drives one to the 

 conclusion that the NH4CI of volcanoes is a juvenile product and that the N2 

 of the atmosphere was formed by outgassing of the Earth. It is relevant to men- 

 tion that the ratios i^N/^^jsj in the rocks and in the atmosphere are almost the 

 same. The primary atmosphere, like the primary ocean, contained NH4+ ions 

 which were not of biogenic origin. 



As concerns the question of CH4 in the primary atmosphere, it must be 

 pointed out that the amount present in volcanic gases is extremely small and it 

 may be supposed that this methane always arises from the reaction of carbon, 

 dispersed in the rocks, with hydrogen, C + 2H2 -^ CH4, or in accordance with 

 the reactions CO + 3H2 -> CH4 + H2O or CO2 + 4H2 -> CH4 + 2H2O on 

 the incandescent lava. In any case Poole [9] has retracted his concept of a primary 

 methane-containing atmosphere. 



Finally, we must consider sulphur and its compounds in the primary atmos- 

 phere. In volcanic gases sulphur is found in the form of H2S and S and is later 

 converted to SO2 and oxidized further. The bulk of the sulphur is, however, 

 fixed in the form of sulphides of iron and other heavy metals below the surface 

 of the Earth. It has been suggested that the S of volcanoes is of secondary 

 origin, that is to say, it is derived from sedimentary formations, e.g. marine 

 sulphates. One may convince oneself beyond question that the sulphur of 

 volcanoes is juvenile in nature. It is accompanied by selenium. More important, 

 however, is the fact that the ratio ^^S/^ss in volcanic sulphur is markedly different 

 from that in sulphates and corresponds with the isotopic composition of the S 

 in stony and iron meteorites [23, 24]. 



A very rough calculation shows that the amount of gas produced on the surface 

 of the Earth must have emanated from the whole thicloiess of the mantie of the 

 Earth. The outgassing of the Earth did not proceed at a constant rate but its 

 intensity was probably determined by the general tectonic rhjrthm of the Earth. 

 The bulk of it was ejected at the beginning of the geological history of the Earth. 

 However, a dense, heavy atmosphere was not formed. Rubey [12] has suggested 

 provisionally that the primary atmosphere contained about 1% of CO2 (instead 



