370 HOW TO REMOVE THE 



proved that the latter was in reality the true cause. 

 I tried often by syringing the water, or drawing it off 

 by means of the siphon, or stirring it about in all 

 manner of ways, to remove the objectionable muddi* 

 ness, but always without success. Limpets and 

 Periwinkles seemed quite useless. Nor did shutting 

 out the rays of light for a few days have any percep- 

 tible effect in subduing the growth of the algse which 

 collected with wondrous rapidity, and arrayed each 

 stone, shell, pebble, and even the poor crabs, in a 

 greenish garb. 



I was therefore under the necessity, on several 

 occasions, of renewing the water, and considering 

 that my residence was several miles from the sea- 

 coast, this task was by no means a pleasant one. 

 What made matters still more provoking, was the 

 fact that the rejected fluid seemed perfectly free from 

 all offensive smell. I now adopt the following novel 

 method for removing the opacity of the water, with- 

 out the latter being changed, and also for preventing 

 the too abundant growth of the algse at all seasons. 



The plan in question (which requires, as already 

 shown, to be carried out with extreme caution by the 

 inexperienced aquarian ist) is merely to dilute a small 

 quantity of alum in a wine-glass full of water, and 

 then mix it with the water contained in the aqua- 

 rium. A pellet of alum about the size of a pea is 

 sufficient for the purpose, if the tank be of moderate 

 size. And if inserted on the first appearance of 



