But artificial water is quite unsuited for animal life of any kind, until it has been brought into condition by means of growing weeds for eight or ten days, and for crustacea, star fishes, and fishes proper, it is not suitable till it has been in use for many months, and even then some species lose their health in it, and at last perish. But for anemones of all kinds, many mollusks and crustaceans, and some other forms to be presently described, artificial water does well, and improves daily if properly managed. Unless, therefore, the aquarian is bent upon domesticating the rarer and more delicate sea specimens, he may avail himself of the aid of the chemist, and manufacture sea-water from the river or the pump.
Composition of Marine Salts.—The limited space of this work will not enable me to enter upon the consideration of the chemistry of this question so fully as I have done in "Rustic Adornments;" nor, perhaps, is it necessary here to do more than point out the simplest method of procedure. There are at least seven ingredients besides water, used in the natural laboratory, but the chemist dispenses with some of these, and finds every purpose served by using a selection of the chief of them. The composition of sea water is as follows:—
| Water | 964.744 |
| Common Salt, or Chloride of Sodium | 27.059 |
| Chloride of Magnesium | 3.666 |
| Chloride of Potassium | 0.765 |
| Bromide of Magnesium | 0.029 |
| Epsom Salts, or Sulphate of Magnesia | 2.295 |
| Gypsum, or Sulphate of Lime | 1.407 |
| Carbonate of Lime | 0.033 |
| Loss, or not accounted for | 0.002 |
| 1,000.000 |
Mr. Gosse, in July 1854, communicated to the "Magazine of Natural History" the results of experiments in the imitation of this composition, and a formula for the artificial preparation of sea-water. In the fictitious preparation the component salts were reduced to four, so that no less than three of the original ingredients were dispensed with. If the reader will note in what minute quantities the bromide of magnesium, the sulphate and carbonate of lime occur, and at the same time bear in mind that river and spring waters always contain a considerable proportion of the last-mentioned ingredient, it will be easily understood that the absence of those materials in the preparation does not materially affect its value. The preparation on Mr. Gosse's plan is composed as follows:—
| Common Table Salt | 3 | ½ | ounces. | |
| Epsom Salts | ¼ | " | ||
| Chloride of Magnesium | 200 | grains, | Troy | |
| Chloride of Potassium | 40 | " | " | |
The recipe may be given in another form to avoid the perplexity of avoirdupoise and troy weights, thus:—
| Common Salt | 81 | parts. |
| Epsom Salts | 7 | " |
| Chloride of Magnesium | 10 | " |
| Chloride of Potassium | 2 | " |
Management of Artificial Water.—When the salts are ready, it is best to mix them in an earthern pan or jar, and allow them to settle and refine for a day or two. To dissolve them in the tank is decidedly a bad plan, though it is daily recommended by the dealers. Any one who will dissolve a portion in a clean bell glass, and allow it to stand for a week, using the clearest water, and adding nothing but the salts, will observe, at the end of that time, a minute gritty deposit, similar to iron rust, mixed with minute fragments of sand. This deposit proves that the chemicals we obtain are not pure; and, perhaps, it is not desirable that excessive purity should be obtained, but it certainly is desirable to keep such matters out of the tank. When the salts have been stirred up once or twice, so as to dissolve them thoroughly, test them for the last time with the hydrometer, till it registers 1.027 or thereabouts; it may safely range from 1.026 to 1.028 without interfering with the success of the experiment. Hydrometers, registered for sea-water, are not everywhere obtainable, and the specific gravity-bulb, sold by Mr. Lloyd, for a shilling, answers the purpose just as well. Mr. Cox, of 100, Newgate Street, has lately supplied me with an hydrometer of a register of 1.000 to 1.050, made in Paris—the cost was seven shillings. I prefer it to the bulb because it can be put to other uses.
A Caution to the Uninitiated.—Some beginners have attempted the preservation of marine specimens in solutions of common bay-salt, and have expressed surprise that they perish rapidly in a solution of salt obtained from the sea. Anyone at all acquainted with chemistry would readily predict, that there could be no more certain way of killing the creatures than the adoption of such a plan of preserving them. When bay-salt is prepared, many of the more soluble materials, chloride of magnesium especially, remain behind in the mother liquor, because the chloride of sodium crystallizes first, hence bay-salt alone does not produce sea-water; we must have the aid of the experienced chemist, or turn chemists and prepare it for ourselves.