om i} 
THE MARINE AQUARIUM. 6: 
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 proceed- | 
ing 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 interest- 
ing 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 com- 
municated 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. 
F 
