371 
of Edinburgh^ Sessio7i 1864-65. 
Cbanonry Point. The upper part is known as the Beauly Firth, 
the intermediate portion as the Inverness Firth, and the outer part 
as the Moray Firth. Two rivers discharge their contents into this 
arm of the sea ; the Beauly Kiver, which flows in at the head of 
the Beauly Firth, and the Eiver Ness, which joins at the head of 
the Inverness Firth. The waters of those rivers are comparatively 
free from saline matter, as during the dry season of the summer 
of 1863 the water of the Ness contained only 2*48 grains of saline 
matter dissolved in the imperial gallon, and the water of the 
Beauly only yielded 3'76 grains of saline matter. Besides these 
sources of fresh water, there are numerous burns which convey 
water, the composition of which is not essentially different from 
that of the Eivers Ness and Beauly. 
Whilst the fresh water flows in at the upper parts, there is sea 
water rolling in and out at the lower part during every flood and 
ebb-tide, and in quantity sufficient to give rise to tides of the 
average height, of eleven feet at certain parts, as at the narrowed 
channel connecting the Firths of Beauly and Inverness. 
The special object of inquiry was to learn the influence of the 
fresh water upon the salt water, and the examination was restricted 
to the determination of three points : — 
Is^, The specific gravity or density of the water, as compared 
with distilled water, taken as 1000* at 60° Fahr. 
The total amount of saline matter dissolved in 1000 parts of 
the water collected at different stations; and 
3c?, The proportion of chlorine present in the various samples of 
water. 
The principal compound of chlorine present in sea water is the 
chloride of sodium (common salt), and there are smaller proportions 
of chloride of magnesium and chloride of potassium; but, in an 
inquiry as to the relative saltness of samples of water from the 
same locality, it is sufficient to determine the amount of chlorine, 
and the calculation of chlorine into chloride of sodium affords the 
most convenient method of recognising the relative amount of fresh 
water which has commingled with the sea water. 
The samples of water employed in these investigations were gene- 
rally collected from a depth of three feet from the surface, but other 
samples were taken from the surface, and from a depth of six feet. 
