THE GASES:IN ROCKS 535 
the evolved gas. In all, 112 complete analyses were made besides 
numerous special or partial analyses connected with various experi- 
ments. These may perhaps be most advantageously and _ briefly 
shown when collected into groups. To make these tables as com- 
plete as possible, not only the results of the author’s studies, but all 
the available analyses of other investigators, have been included in 
the lists. Except in the case of four of the five analyses by Tilden, 
relative to which sufficient data are not given, all of the figures in 
these tables refer to volumes of gas per volume of rock. Previous 
investigators have usually given the total volume of gas and the per- 
centages of each constituent. From these I have calculated the vol- 
umes for each individual gas. The numbers in the first column are 
the analysis numbers used in Table 8 of the original paper." 
In making the averages of the analyses, it should, perhaps, be stated 
that in those cases where, on account of excessive carbonation of the 
rocks, no figures are given for carbon dioxide, the average amount 
of this gas calculated from the other analyses is assumed to be 
present. This addition is made to the average total and makes this 
figure slightly greater than the average of the column which it foots. 
The same method has been used for carbon monoxide in the three 
of Travers’ analyses where carbon monoxide and hydrogen are 
put together. 
The figures for the Orgueil meteorite which yielded such a remark- 
able amount of sulphur dioxide make the average for the sulphur 
gases an abnormal one. ‘The presence of this gas in quantity must 
mean that the meteorite has suffered much from weathering and oxida- 
tion subsequent to its fall. Considerable troilite has passed into iron 
sulphate which has been decomposed by the heat of the combustion- 
furnace. 
Omitting the sulphur dioxide of this specimen, the average total 
volume of gas from stony meteorites is reduced to 4.80 times the vol- 
ume of the meteoritic material. 
Methane was determined in only two of these analyses. In these 
two it averaged 0.10 volume; but in order to make the figures con- 
sistent in the table, it was necessary to average these as if the eight 
other meteorites yielded no marsh-gas, though it is highly probable 
1 Carnegie Publication No. 100, pp. 14-22. 
