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 O'Oo 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 O'l 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. 



Temperature Observations. During the various visits to the different 

 lochs, many observations were made on the temperature of the water, 



