14 
ever closely its composition may be imitated in these days of 
accurate analysis, there are principles in it which no chemist can 
supply. There are, however, many difficulties in obtaining real sea 
water in London, and in some inland localities these would con- 
stitute an almost insuperable barrier to the establishment of an 
aquarium had we not the artificial substitute to fall back upon. 
But since science has furnished us with the constituents of sea 
water, this may be concocted in any place where the necessary 
chemical salts can be obtained, and we may feel great confidence in 
employing it, since most of Mr. W. Alfred Lloyd’s first observations 
were made while using it, and in his hands it was productive of 
very satisfactory results. As the cost of its production is about 
8id. a gallon, I shall introduce to your notice the formula for 
making it, as given by Mr. Gosse in his ‘‘Handbook to the Marine 
Aquarium : ’’— 
raeanir otet H yal io ane Avoirdupois. 
Chloride of Magnesium, 200 grains Troy. 
Chloride of Potassium, 40 
These salts are dissolved in little less than four quarts of fresh 
water, so that a specific gravity bubble of 1.026 would just sink in 
it. Having made sufficient of this solution to fill your tank, wash 
several handfuls of freshly-gathered sea-weeds in it, especially 
‘‘ Ulva latissima,” but do not leave them permanently in; also add 
any pieces of rock that may have Marine Alge growing on them, 
and let the water be exposed to the sunlight for about a fortnight. 
At the end of that period it will be fit for the reception and healthful 
preservation of your animal life, the rockwork will have become 
fairly covered with the growing Diatoms, and the germs of marine 
vegetation will be giving off a plentiful supply of bubbles of oxygen. 
Now, all these preliminaries may seem very tedious to those who 
are anxious to see their tank blossoming with all its animal beauty, 
but the great error into which so many fall who start an aquarium, 
is that of being in a hurry to see the occupants placed in it before 
its vegetation has sufficiently advanced to supply the atmosphere 
necessary to their existence, and thus too many begin in haste and 
leave off in disgust; but follow minutely these details, and I promise 
you success and satisfaction. There are one or two pieces of 
accessory apparatus which, while not of absolute importance, yet 
will be of great service—a specific gravity bubble, that will just sink 
in sea water of the right density, may be kept in your tank ; if it 
floats to the top of the water you may know that the water has 
evaporated and become too salt, when it will require diluting with 
fresh water till the bubble slowly sinks again. Many mark the side 
of the tank by gumming a piece of paper at the level of the water, — 
but this method is not sufficiently delicate. I have recently added 
a means of injecting atmospheric air into my aquarium, which serves 
99 
