374 BOTANICAL GAZETTE [xoveunes 
The following table shows some other physical properties of these 
several varieties of peat. 
Cassandra- 
Fresh Tamarack Chelsea Onion 
née | Sphagnum Fg 3 Zone Peat | Bog Peat |Marsh Muck 
be ea 87.0 78.0% gI.o 84.0 82.0 75.0 
by weight........ 892.0 | 1550.0 960.0 530.0 477.0 283.0 
ir H,O-con- 
OD ni OUR Ce ree er 8.5 10.6 10.0 10.0 10.0 10.0 
*Low volume percentage due to air present in tissues. 
These measurements were made by placing the peat samples in a 
zinc cylinder of 600 °° capacity. The bottom of the cylinder was 
closed with a wire gauze cap. The moist peat. was tamped into the 
cylinders with as nearly uniform a stroke as possible. The cylinders 
were then set in a dish of water for eighteen hours, after which the 
cylinder was removed and allowed to drip. When all dripping had 
ceased, the cylinder was weighed. The peat was then removed and 
allowed to dry at room temperature, and again weighed. Finally it 
was dried at 110° C., and the absolute weight determined. As usual 
in such measurements, considerable irregularity was shown by the 
different samples, owing to the difficulty of removing the air, and of 
packing to the same degree. However, the figures bring out clearly 
the fact that sphagnum more than any other plant influences the 
water-capacity of a peat containing it. The eriophorum peat has 
lower capacity, owing to its coarse fibrous structure. Of the series 
examined, the highest water-capacity was found in the cassandra 
zone. The effect of further decay and destruction of the plant tissue 
is shown by the reduction in water-capacity of the last three _— 
of the series. The percentages are of interest in connection with the 
utilization of such lands for agricultural purposes, in showing ‘ 
difficulty of proper drainage. It is the experience of the men W Z 
ditch these bogs that until the peat has reached the condition term 
“muck” the ditches act only with extreme slowness. 
Chemically, peat or humus is made up of varying 
several substances of a rather indefinite character, wh 
monly classified among the dehydration products of 
ich are com- 
the carbo- 
