18 



THE AQUAEIUM, JANUARY, 1893. 



the Chinese adorned their houses and 

 gardens with aquariums, the old Egyp- 

 tians and tlie noble Komans had theirs, 

 in which they cultivated choice water- 

 plants and fish. During the middle 

 ages we find rare and beautiful fishes 

 and aquatic plants in jDrecious basins in 

 the famous castles of Euroj)e. 



The aquarium of those days was of 

 course quite different from the aqua- 

 rium of the present. The manufacture 

 of sheet-glass not being invented then, 

 the tanks containing the collections 

 were basins formed of costly stones or 

 china, and the contents could only be 

 viewed from above. 



Whether the scientific principles 

 upon which the success of an aquarium 

 is based were already understood by 

 the ancients, is not known and now 

 hard to prove. At any rate, the present 

 manner of sustaining an aquarium 

 through the action of aquatic plants 

 without change of water, is based on 

 Ingenhauss's discovery, made in the 

 second half of the eighteenth century 

 that ''plants when exposed to the action 

 of light emit an air luliich he announced 

 as oxygen gas." 



Fish inhale the oxygen contained in 

 the water and exhale in turn a gas 

 called carbonic acid gas,, a very poison- 

 ous compound, this the plants inhale 

 and appropriating the carbon to build 

 up their own tissues, give off the oxy- 

 gen again for the fish, so that this gas 

 oxygen becomes but a carrier of carbon 

 from the animal economy to that of 

 the vegetable. When the sua shines 

 on the plants in our aquarium, very 

 often their leaves will be seen to be 

 covered with an innumerable assem- 

 blage of minute globules of that gas, 

 glistening like dew-drops upon grass. 



Carbonic acid gas is heavier than 

 oxygen. It is the same body tliat col- 



lects in wells and in some of our mines-, 

 and which is also given off from stoves, 

 often causing disease and death. When 

 this gas is present in too large a quan- 

 tity the fish feel uncomfortable at the- 

 bottom, they go near the surface of the- 

 water and finally are forced to breatli& 

 the oxygen contained in the atmos- 

 phere. 



This discovery, like many useful 

 others was from year to year improved,, 

 and could these scientists of bygone 

 days see the parlor aquarium of Amer- 

 ica to-day, inhabited with plants and 

 animals from every zone of the globe,^ 

 see fishes and amphibians bred in 

 them, not solely by professionals, but 

 likewise by lady amateurs, observe 

 the joy it creates in the child, the in- 

 valid, or the sick in the bed chamber,^ 

 they would justly feel proud, for they 

 were unknowingly great benefactors to 

 man. 



An aquariuin is also very beneficial 

 in improving the sanitary condition of 

 a living or bedroom through its purify- 

 ing influence on the atmosjjliere. All 

 the impurities of the air are absorbed 

 by the water, this is in turn purified by 

 the plants and the water evaporating 

 into the room is j^erfectly pure. 



As we have seen above, the founda- 

 tion of an aquarium is the plant life. 

 When one has concluded to get an 

 aquarium into his house, the first thing^ 

 that should be considered is the loca- 

 tion of the tank. 



The best side of a room for the aqua- 

 rium is that having a window near 

 which it is to be placed, as the light 

 can be increased or reduced by regu- 

 lating the shades accordingly. The- 

 best exposure is that towards the North;, 

 by such an exposure the aquarium 

 should stand about six inches away 

 from tlie wiiulow; next best is oner 



