262 WATER. 



they will tinge the water after any amount of washing, 

 the former with lime, the latter with ochre. 



Small pehbles or fine gravel, likewise well washed, 

 may be used to vary the bottom with the sand. 



Masses of rock, of dimensions suitable to the 

 Aquarium, should be put in to afford shelter and con- 

 cealment to such animals as like the gloom. To afford 

 this in the highest degree, a flat piece may be set, like 

 a table, or cromlech, upon two or three upright blocks ; 

 or two tall pieces may lean against each other, forming 

 a rude arch; — care being taken, whatever arrangement 

 be chosen, that the masses stand with stability. It is 

 of little consequence what sort of rook is selected, — 

 limestone, sandstone, granite, conglomerate, — but the 

 rougher, and the more full of cavities and angles, the 

 blocks are, the better will be the effect. 



Water. — The purity of the water is of great import- 

 ance. In London, sea- water may be easily obtained, 

 by giving a trifling fee to the master or steward of any 

 of the steamers that ply beyond the mouth of the 

 Thames, charging him to dip it in the clear open sea, 

 beyond the reach of rivers. I have been in the habit 

 of having a 20 gallon cask filled for me, for which I 

 give a couple of shillings. 



The vessel in which it is conveyed requires atten- 

 tion. A cask is the best, if a considerable quantity 

 of water is required ; but it is absolutely indispensable 

 that it should be either new, or at least that nothing 

 injurious should have been previously contained in it, 

 such as spirits, wine, chemicals, acids, &c. ; since no 

 soaking will prevent hurtful qualities from being com- 

 municated to the Water. Even the bungs ought to be 



