118 SEA-WATER AQUARIA 



sea-water in a natural state, it can be made artificially. Gosse 

 produced, in 1854, a formula for the purpose which answers 

 admirably, viz. — Common table salt, 3J ounces (Avoir.) ; Epsom 

 salts, I ounce (Avoir.) ; Chloride of Magnesium, 200 grains (Troy); 

 Chloride of Potassium, 40 grains (Troy). These salts to be dis- 

 solved in rather less than four quarts of ordinary drinking water, 

 so that the solution attains a specific gravity of 1027. If the 

 hydro7?ieter shows a figure higher than 1027, then more water must 

 be added; if under 1027 more of the salts are needed. 



Perhaps the simplest method is to procure some of Southall's 

 Aquarium Sea Salt, in each package of which is a measure and 

 the directions : — " For sea-water of full strength add a gallon of 

 water to each measureful of salt." For aquarium purposes, adjust 

 the specific gravity with a hydrometer or gravity bubble, so that its 

 specific gravity shall be T027 at 60^ Fah. This salt " was used in 

 preparing sea-water for the Royal Aquarium, Westminster^ and for 

 the magnificent aquarium at Aston, Birmingham, where 200,000 

 galls, were in constant use." 



It is an advantage, however, to obtain natural sea-water, if this 

 is possible, since it contains myriads of microscopic animal forms, 

 which multiply and serve as food for the creatures in the aquarium, 

 and also countless invisible vegetable germs or spores which, under 

 the influence of light, will develope into a low form of vegetation. 

 Yet water from the sea-shore (shore-water), though suitable for 

 animal life in a state of nature, is very frequently found at first to 

 be quite unfit for use within the narrow limits of an aquarium. 

 For example, the 100,000 gallons of " beautifully clear sea-water in 

 the Crystal Palace Aquarium " was, when first received from the 

 shores of Brighton, " neither well-coloured nor of high density, 

 nor in any way fit for the maintenance of animals." 



One can easily understand this. Shore-water is often more or 

 less impure from the introduction of sewage, refuse, and other 

 impurities from the land ; but such deleterious matters are con- 

 tinually counteracted and destroyed by the air absorbed by the 

 immense and ever-changing water surfaces exposed to the atmo- 

 sphere through the agency of waves, tides, currents, and the 

 natural movement of the sea ; and this purifying process is enor- 

 mously increased by the action of numberless healthy, growing, 

 and vigorous seaweeds. 



