HAWKESBURY SANDSTONE 
124 
Geology of Sydney. 
reciprocally tlie power which 
this peroxide has of oxidizing 
and consuming these same 
organic matters, which are 
2 thereby finally converted into 
'> carbonic acid and water. This 
^ last action, let me say, in pass- 
£ ing, is illustrated by the des- 
S tructive action of rusting iron 
2 bolts on moist wood, and the 
^ effect of iron stains in impair- 
<D , 
r§ mg the strength of linen fibre. 
m We see in the coal forrna- 
o 
^ tion that the vegetable mat- 
es 
■J ter necessary for the produc- 
| tion of the iron-ore beds was 
^ not wanting; but the question 
g has been asked me, where are 
J the evidences of the organic 
g material which was required 
^ to produce the vast beds of 
c . . 
.2 iron ore found m the ancient 
o 
m crystalline rocks? I answer 
that the organic matter was, 
cc r 
o in most cases, entirely con- 
^ surned in producing these great 
results, and that it was the 
large proportion of iron dif- 
fused in the soils and waters 
of these early times, which not 
