eee eS SS 
THE MARINE AQUARIUM. 63 
Those not experienced in chemical manipulations may 
find some difficulty in obtaining and weighing accurately 
the several ingredients; and I should advise them to 
purchase the preparation sold by Mr. Bolton, of 146, 
Holborn Bars. This merely requires to be dissolved 
according to the instructions just given. Mr. Bolton 
has given minute attention to the preparation of the 
salts, and is now improving them by compounding with 
them the minute quantities of the more subtle ingre- 
dients, which were originally omitted by Mr. Gosse. 
The salts are sold in packets, at the rate of three gallons 
for a shilling ; a price which must be considered reason- 
able when we consider the purity of the article, and the 
care taken in its manufacture. 
Filtering.—When the salts are well mingled with the 
water, pass the liquid, through a filter, into the tank, 
which is supposed to have been already well-seasoned, and 
furnished with a bottom of sand and pebbles, and any 
ornaments that may be deemed necessary. A bee glass, 
with a bit of sponge thrust into the orifice, is a convenient 
form of filter, but if such a thing is not at hand, take an 
old flower pot, and wash it quite clean, thrust a piece of 
sponge through the hole in the bottom, and throw into it 
a handful of powdered charcoal. This may be suspended 
above the tank, or stood on two slips of wood, and filled 
from time to time, till the whole of the water has been 
passed through it. 
Some healthy plants of Ulva latissima and Enteromor- 
pha compressa are now to be introduced, and the whole 
left undisturbed for at least a week or ten days, when the 
