AQTTABIUM. 



ing dowii air in small bubbles with it, will be maintained bj 

 these means in a state of perfect purity ; in fact, as observes 

 8. clever reviewer of Mr. Gosse's work on marine aquaria, 

 " there is no reason why the same supply of sea- water should 

 not last for a twelvemonth or even longer. Of course during 

 all this time loss by evaporation has to be supplied ; but as 

 the evaporation is of pure water only, all the salts remaining 

 and becoming concentrated, it is only necessary to prevent that 

 concentration by pouring in again as pure water whatever ig 

 poured out as watery vapour." 



Should the proprietor of the marine tank, however, distrust 

 this theory, there is no reason why he should not replenish the 

 vessel with the genuine article just as often as he thinks proper, at 

 an expence of sixpence a gallon. Whether all dealers in marine 

 aquaria make this provision for their customers, or whether 

 the trade is in the hands of a few of the best houses, I can't say. 

 I know at least two dealers of whom sea-water may be bought : 

 Mr. Lloyd, of 20, Portland-road, Regent's-park ; and Mr. Hall, 

 75, London-wall. Nay, thanks to Mr. Gosse, the economist 

 may save a fair portion of his sixpence by manufacturing his 

 own sea-water. The following is the receipt : — 



Common table salt ....... 3^ omices.. 



Epsom salts i ounce. 



Chloride of magnesium 200 grains troy. 



Chloride of potassium 40 „ „ 



These materials, added to a gallon of water and thoroughly 

 mixed, and there, in your parlour in PentonvUle, you may be 

 gratified by the sight, and feel, and taste of the " briny ocean," 

 or something like it. 



The tank prepared and the sea-water at hand, put in youi 

 bottom layer of sand. That from the sea-beach is of course 

 the best, but if this cannot be obtained, well-washed river-sand 

 win do nearly as well. Bits of rock may or may not be added, 

 just as the fancy of the builder suggests. " Now for your 

 plants. Brown and olive sea-weeds should be avoided ; they 

 cannot endure the narrow limits of your tank, and will speedily 

 die. Red and green weeds are the sturdiest, and without 

 doubt the most beautifnl. The " sea-lettuce " is recommended 

 by Mr. Gosse, and certainly its broad, vividly-green leaves, 

 delicate as gossamer, are very lovely ; moreover, it is easily 

 obtained, and wiU hardly be sought in vain between tide-marks 

 if the hoUowg in the rooks are examined. Whatever plants be 



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