THE FRESH- WATER LOCHS OF SCOTLAND. 23 
diatoms; the loss on ignition, after drying at 90° C., amounted to 
14 per cent. 
The mud from the deeper part of Loch Drunkie was of a dirty brown 
colour, containing 10 to 20 per cent, of mineral particles with a mean 
diameter of O'l mm., but consisting principally of amorphous clayey 
matter, with many small mineral particles, and vegetable matter. A 
few diatoms were observed. The loss on ignition, after drying at 90° C., 
amounted to 26'38 per cent. 
The deposit from the deeper parts of Loch Arklet was similar to that 
from Loch Drunkie, with even a larger quantity of vegetable matter. 
The mud from the deeper parts of Lochs Doine and Voil was of a 
brown colour, with 30 to 40 per cent, of mineral particles, and clayey 
and vegetable matter, and a few diatoms. A sample from a depth of 
80 feet in Loch Voil, after drying at 90° C., gave 22'74 per cent, loss on 
ignition. 
The material from a depth of 136 feet in Loch Lubnaig was a brown 
impalpable mud, with 30 to 40 per cent, of mineral particles, much 
clayey and vegetable matter, and a few diatoms. The loss on ignition, 
after drying at 90° C., amounted in one sample to 16'29 per cent., and 
in another sample to 15*76 per cent. 
Three brown muds were examined from Loch Chon, from depths of 
10 feet, 14 feet, and 37 feet. The colour was lighter, and the mineral 
particles were more abundant and larger, in the shallower water. In 
the deposit from 10 feet the mineral particles made up probably 35 
to 40 per cent., and included a few rock fragments which sometimes 
attained a diameter of 10 mm., the mean diameter of the mineral 
particles exceeding 0‘05 mm. in diameter being about 0’3 mm., while in 
the deposit from 37 feet the percentage falls to about 10, with a mean 
diameter of OT mm. Inversely, clayey matter and vegetable matter 
were more abundant in the deeper water, mixed with minute mineral 
particles, impregnated with ferric oxide, and containing diatoms. 
Sponge spicules, arenaceous Foraminifera, and Entomostracous skeletal 
fragments. 
A sample from the deepest part of Loch Ard was a dark-grey mud, 
consisting principally of vegetable and clayey matter, the mineral 
particles not exceeding 10 per cent., with a mean diameter of about 
O’l mm. The organic remains observed were the same as in Loch Chon. 
A fine-grained dark-brown mud from a depth of 60 feet in Loch 
Leven contained probably not more than 5 per cent, of mineral particles 
exceeding 0'05 mm. in diameter, the bulk of the deposit consisting of 
clayey and vegetable matter, containing many beautiful diatoms, with 
Sponge spicules and Entomostracan remains. 
T emperature Observations . — During the various visits to the different 
lochs, many observations were made on the temperature of the water. 
