William Mattieu Williams

“ Allowance must always be made for the reflected colour of the sky shown in certain positions.
Other lakes are as nearly colourless as an imperfectly transparent liquid can be, and contrast remarkably with the intensely blue lakes above named.
All such colourless water that I have seen has either been supplied by the surface drainage of siliceous rocks, subject to little or no torrent grinding, or by springs passing through hard limestones. These contain limestone in solution, but no suspended coloured particles. ”

“ All these black lakes that I have seen in Norway, Scotland, Ireland, &c., are fed by rivers that flow through peat bogs, and dissolve from the peat a sufficient amount of bituminous matter to give the water when examined in small specimens the appearance of weak tea. The chief feeder of the Jolster Vand is as dark as very strong tea. ”

“ Thin films are semi-transparent and have the colour of strong tea, which grows darker with increased thickness and opacity. All this is due to invisibly minute particles of black carbon suspended in a resinous medium. ”