of Edinburgh, Session 1871-72. 553 
tests I have used as described above. Sometimes their salts are 
scanty; but always they are quite colourless. Their solids appear 
to vary from a 16,000th to a 21,000th; and chlorides and lime- 
salts are, for the most part, indicated by their proper liquid tests 
rather more distinctly than in the general run of stream waters in 
their ordinary state of fulness. Several small springs high on the 
hill slopes have yielded these results. Similar in that respect is a 
copious spring in Grlen Beg, more familiarly known by the name 
of Hell’s Grlen, about three miles from Loch-G-oil-head in the 
narrow pass to St Catherine’s on Loch Fyne. This spring, which 
gushes in force near the highway and close to the valley stream, 
is at all times beautifully limpid, and seems to be little affected 
in volume by droughts or floods. Its temperature is 41° when 
the air is 64° and more, though its site is not much over 300 
feet above the sea-level. Its water is perfectly colourless, but 
contains rather more chlorides and earthy salts than the waters 
of the streams in their ordinary condition. Another more re¬ 
markable spring of great volume issues from the south flank of 
the Cobbler, about 1500 feet perpendicular above the bottom of 
Grlen Croe, and leaping from rock to rock, joins the Croe about half¬ 
way up the glen. In the very dry season of 1870, its course was the 
only one which showed any water among the many which score 
the steep slope of the mountain where it overlooks the glen from 
the north. I found the water last autumn, after ten days of com¬ 
plete drought, to be perfectly colourless, and to be so free from 
saline matter as to be barely affected even by the delicate liquid 
tests for chlorine and for lime. 
As the various streams now described are the feeders of the 
fresh-water lakes, which abound in the mica-slate districts, the 
composition of the water of the lakes must be the same with that 
of the average water of the streams. The small upland “tarns” 
are peaty, owing to the peat which paves and surrounds them. 
But the great low-lying lakes present very little solid matter of any 
kind in their waters; their scanty salts consist of chlorides, car¬ 
bonates, and sulphates, the bases being lime, soda, and magnesia; 
and the organic colouring matter is so small as to be discoverable 
by delicate tests only. In all instances, however, our purest lake 
4 E 
VOL. VII. 
