64 PREPARATION AND MOUNTING 



like a cross, and many whose shapes no words could describe. 

 The greater part, perhaps, of those which are usually sold, is from 

 the rocky parts of Bermuda ; but they are also found in Sicily, 

 some parts of 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 

 Diatomacese, but the process is a different one. Sometimes this 

 is effected by simply washing until they are freed from all extra- 

 neous matter, but this is seldom as effectual as it should be. In 

 the Microscopic Journal Mr. Furlong gives the following method 

 of treatment as the best he knew : 



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 common 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 re- 

 maining lumps with a soft bristle brush. Add soda and water as 

 before, and boil again ; then pour off the liquid into the large ves- 

 sel, and repeat until nothing of value remains. Stir the large ves- 

 sel 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. Each washing brings off a kind of" flock," 

 which seems to be skins. 



3RD PROCESS. Put the shells in precipitating glass and drain 

 off the water until not more than J oz. remains. Add half a tea- 

 spoonful 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 transparent. Wash well now with 

 water to get rid of all salts and other soluble matter. 



