100 PREPARATION AND MOUNTING 
Africa and America. They are usually mounted in balsam. 
but are equally beautiful mounted dry, and used with the 
lieberkuhn. ‘They require as much care in cleaning as the 
Diatomacez, but the process is a different one. Sometimes 
this is effected by simply washing until they are freed from 
all extraneous matter; but this is seldom as effectual as it 
should be. In the Microscopic Jowrnal Mr. Furlong gives 
the following method of treatment as the best he knows :— 
Procure— 
A large glass vessel with 3 or 4 quarts of water. 
New tin saucepan holding 1 pint. 
2 thin precipitating glasses holding 10 oz. each. 
Take 3 oz. of dry Barbadoes earth (lumps are best), and 
break into rather small fragments. Put 3 or 4 oz. of com- 
mon washing soda into the tin and half fill it with water. 
Boil strongly, and having thrown in the earth, boil it for 
half an hour. Pour nine-tenths of this into the large glass 
vessel, and gently crush the remaining lumps with a soft 
bristle brush. Add soda and water as before, and boil again; 
then pour off the liquid into the large vessel, and repeat 
until nothing of value remains. Stir the large vessel with 
an ivory spatula, let it stand for three minutes, and pour 
gently off nine-tenths of the contents, when the shells will be 
left, partially freed only, like sand. 
2nD Process.—Put common washing soda and water into 
the tin as before, and having placed the shells therein, boil 
for an hour. Transfer to the large vessel as before, and 
after allowing it to stand for one minute, pour off. Hach 
washing brings off a kind of “ flock,’ which seems to be 
skins. 
38RD Process.—Put the shells in a precipitating glass and 
_ drain off the water until not more than 3 oz. remains. Add 
half a teaspoonful of bicarbonate of soda, dissolve, and then 
pour in gently 1 oz. of strong sulphuric acid. This liberates 
the “flock,” &c., and leaves the shells beautifully trans- 
parent. Wash well now with water to get rid of all salts 
and other soluble matter. 
