280 GENERAL DIRECTIONS. 



Purification. — As soon as this begins to be per- 

 ceived, tlie whole water should be drawn off by means 

 of a siphon, without disturbing the sediment, into 

 pans, into which, for the present, the plants and 

 animals may be put. The Tank should be wiped 

 out and rinsed, and then the water should be filtered 

 back into it. This is a very simple process : a funnel 

 (if of glass, earthenware, or gutta-percha, the better) 

 is placed over the Tank, with a bit of sponge pushed 

 lightly into the top of the tube, so as to allow the 

 water to run through in a narrow, thread-like stream. 



Keplace the plants and animals, reserving those 

 pieces of rock, or those shells, that look suspicious, 

 which may be kept in a bowl of water by themselves 

 for a few days, till their state appears more fully. 



This process of bringing every drop of the water 

 into contact with the atmosphere, is an effectual 

 remedy for destroying the tendency to putrefaction ; 

 as the animal fluids and solids held in suspension 

 enter into combination with the oxygen of the air, 

 and form the pure innocuous gas called ozone. The 

 result will be that the milkiness will rapidly disappear; 

 the water will assume a transparent clearness, which 

 will in all probability be permanent ; the plants will 

 thrive, and the animals will be livelv. This result 

 will be rendered still more secure by filtering the water 

 through pounded charcoal, and by allowing some 

 pieces of the same substance to float in the tank. 



Should it happen that from oversight or ignorance, 

 or any other cause, putrefaction has thoroughly set 

 in, still you need not lose the water. Take out any 

 animals that are yet alive, as well as the weeds, and 



