THE AQUARIUM. 445 



selves unceasingly in licking the glass (p. ]61), and may be watched with a 

 magnifier of moderate power. 



Artificial salt-water. — The difficulty of obtaining sea-water has been 

 obviated by the manufacture of salts for the formation of medicinal baths, by 

 evaporating large quantities of the sea-water itself. This plan was sug- 

 gested by Dr. E. Schweitzer, whose analysis of the water of the English 

 Channel, taken off Brighton, shews the following salts in lOOlbs. (or 10 

 gallons), stated in decimal fractions of the pound, and also in ounces and 

 grains : — 



Chloride of sodium 2.706 43^ ounces, 



magnesium.. 367 6 „ 



potassium 0.070 1.^ „ 



Bi-omide of Magneaium 0.003 21 grains 



Sulphate of magnesia.. 0.230 7| ounces ) ^ 



- lime 0.140 2| „ } Crystals. 



Carbonate of lime 0.003 21 grains 



As the weight of the salts amounts to 60f ounces, the true proportion of 

 water to be mixed with them will be 3 pints less then 10 gallons.* 



The temperature of the aquarium should not range below .50° nor above 

 70°. The mean temperature of the sea is estimated to be about 56" Fahr. 

 with a variation of about 12° throughout the year. In hot summer days a 

 screen is necessary against strong sunlight. f {Warington). 



Many little points, in the management of the aquarium, will be deter- 

 mined by experience ; such as the number of living animals it is capable of 

 maintaining, and the sorts which may be safely kept together. Everything 

 dead or decaying should be removed as soon as detected. The loss by eva- 

 poration may be supplied occasionally by sprinkling with distilled water.| 



* These salts are manufactured Vy Messrs, Brew and Schweitzer, 71, East Streets 

 Brighton; the proportion ordered to be used is 6 oz. to the lallon of water, and 

 stirred well until dissolved. 



There are few inland towns without a fishmonger, through whom maybe obtained 

 live periwinkles (occasionally tenanted by the hermit-crab), and oyster-shells incrusted 

 with serjoMte and sea- weed, some of which maybe still living. The stickle-back is 

 almost the only fresh-water fish capable of existing in a marine aquarium. 



t In a sitting-room with a south aspect and good fire daily, the temperature of a 

 thirty-gallon aquarium has been known to fall as low as 45'' on several occasions, 

 though screened at night by a blind. (Warington, An. Nat. Hist. 1855, p. 315.) 



t Hand-book of the Marine Aquarium. P. H. Gosse. 12mo. Lend. 18-5.5. 



