tank, in which there was not a single drop of natural sea water. Mr. Hall tells me he has, on emergencies, kept them alive for a week in soap-suds, and even in more offensive liquids; and judging by the life the creature leads on the sea shore, now submerged in the cool waters, and now exposed to the burning sun, it is not at all surprising that it has a hardy constitution. Still, this hasty proceeding is not to be recommended; let time develop the powers of the water, let the solar light reach the plants through the green medium of the stained glass, and soon a lovely beading of oxygen bubbles will appear, to indicate that all is right, and then the animals may follow each other in proper order to their domestic home.
If a little real sea-water, even a pint or two, can be obtained to mix with the artificial, the ripening of the latter will be considerably hastened, but it is an interesting fact in the chemistry of the aquarium that, though in the first preparation of sea-water certain of the ingredients are left out of the prescription, in process of time those very same ingredients are to be discovered in it by means of analysis. How do they get there? They are communicated to it by the vegetation, and hence as the water acquires age, like good wine, it increases in strength, and after some months use, will maintain creatures in health that would perish in a day in water recently prepared.
The preparation costs, when prepared from ingredients bought at wholesale price, about three-pence a gallon; but it is a much better plan to purchase it ready prepared, the price then being only four-pence per gallon, or a three gallon packet for one shilling.
