288 BOTANICAL GAZETTE [OCTOBER 
in the various reports of the chemist of the Experimental Farm, 
cited in the Bibliography. 
The marsh soil, however, is not always red and rich, but it 
is in places blue and barren. This blue soil occurs in low 
badly drained places, is but a few inches deep, and is underlaid 
by red soil, which occurs everywhere in a layer under the bogs. 
Bands of it appear occasionally on river banks in the rich well- 
drained marsh; but, as already pointed out, this is without 
doubt due to the wandering of the rivers, which, in changing 
their courses, cut into spots previously back from their courses 
and badly drained. The blue soil seems, however, at times to 
underlie the “ sedge-bogs” along the rivers. A full account of 
the formation of this blue soil is given by Dawson in his Aca- 
dian Geology (p. 24 of the third edition) as follows: 
The chemical composition of this singular soil, so unlike the red mud 
from which it is produced, involves some changes which are of interest both 
in agriculture and geology. The red marsh derives its color from the 
peroxide of iron. In the gray or blue marsh the iron exists in the form of a 
sulphuret, as may easily be proved by exposing a piece of it to a red heat, 
when a strong sulphurous odor is exhaled, and the red color is restored. The 
change is produced by the action of the animal and vegetable matters present 
in the mud. These in their decay have a strong affinity for oxygen, by virtue 
of which they decompose the sulphuric acid present in the sea-water in the 
forms of sulphate of magnesia and sulphate of lime. The sulphur thus 
which gives to the mud its unpleasant smell. This gas dissolved in the 
water which permeates the mud, enters into combination with the oxide 
of iron, producing a sulphuret of iron, which with the remains of the organic 
matter, serves to color the marsh blue or gray. The sulphuret of iron remains 
unchanged while submerged or water soaked, but when exposed to the 
atmosphere, the oxygen of the air acts upon it, and it passes into sulphate 
of iron or green vitriol—a substance poisonous to most cultivated crops, and 
which when dried or exposed to the action of alkali tances deposits the 
hydrated brown oxide of iron. Hence the bad effects of disturbing blue 
These substances he supposes to be derived from the trap rocks at the entrance to 
Minas Basin, which rocks are absent on the Chignecto Branch. Hence he says, the 
Minas marshes have shown no signs of exhaustion, while the Chignect arshes have. 
Comparative analyses of samples from both sets of marshes as far as available do not 
sustain this contention, nor, indeed, as far as I can learn, is he correct in his estimate 
of the relative lastingness of the fertility of the two sets of marshes. 
Biisine Soest 
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