« 
# 
»*» *t* 4j. w «t 
ates hydrogen &x lj?hide to such a extent that its odor is very noticeable 
and the gas is readily detected chemically-. tW$ gas, itself a plsnfc 
poison, has changed the ferric compounds of the soil to poisonous ferrous 
compound s • 
The hydrogen sulphide and ferrous ctmpminds arc quickly oxidised Into 
non-po.iconous compounds when they co-fee in contact with the air, and hence 
they are- so changed in the upper inch or t wo of soil as to render a thin 
sfcrsturn hatetable to the roots of rat lous wsophytf s. The well drained 
soil on the steeper elopes of the gulches ir> for like reasons kept suf¬ 
ficiently free from the harmful coz^cfes&ls to permit of the growth cf the 
I ' « A ' » r !* >4v'- , I 
native trees. 
A chemical analysis of a sample -of soil taken from among dying trees 
is given below. Tills sample included the upper three inches ef soil* 
4 
Analysis of Hydrochloric acid <1.115 sp. gr.) extract. 
I sw&olitb le mat t er 
71.32 
To %» sh 
.48 
Soluble silica 
,78 
Soda 
..25 
Xiae 
.04 
Magnaoia 
.98 
Manganese oxide 
.02 
Pen ic oxide 
1.48 
Ferrous oxide 
5.75 
Alumina 
5.70 
pho sphorms pen tox id e 
.02 
Sulphur trioxi&e 
.00 
Chlorine 
•04 
Volatile matter 
12.54 
W40 
Uitrogcn* moisture free .292 
Reaction, acid 
Of 28.08 parts of soluble matter it will h noticed that 5.75 parts 
are ferrous oxide; or in otter m rds, of the soluble matter in this 
soil is ferrous iron. The relatively enormous quantities in which this 
gt.f \$<k. 
