MEMORANDA. 65 



in the earth, and let it boil for half an hour or more ; take off the 

 fire and pour about nine tenths of Avhat is in the saucepan into 

 the large glass vessel holding the cold water. The undissolved 

 lumps which remain in the tin may now be gently crushed 

 with a soft bristle brush, soda and water added as before, 

 and boiled again ; pour off as before, and repeat the pro- 

 cess until [nothing of value remain in the tin. Then take 

 an ivory spatula, and stir round and round the contents of the 

 large glass vessel; let it stand for about three minutes, and then 

 pour off gently nine tenths of the contents, a considerable 

 quantity of a sandy-looking substance will be found at the 

 bottom. These are the shells partially freed from the 

 matrix, but still very unclean. Wash out your tin, cover 

 the large glass vessel, and the shells will keep for the next 

 leisure evening. 



Second process. — Put common washing soda, as before, 

 and water into your tin ; transfer all your shells into the tin, 

 and boil as before for an hour or more. Transfer all into 

 the large glass vessel containing water, as before, and after 

 standing one minute pour off the muddy contents ; add a large 

 quantity of cold water, stand for a minute, and pour off. 

 The shells may now be transferred to one of the precipitating- 

 glasses. 



Each washing brings'over'more and more of a kind o^ flock, 

 which seems to be the skins of the sarcode bodies of those 

 minute creatures. 



We are now ready for the third process. 



Drain off the water from the shells which are in vour 

 precipitating-glass imtil not more than half an ounce of water 

 remains above them; add about half a teaspoonful of bi- 

 carbonate of soda, which will dissolve perfectly with a little 

 warmth; then pour' in gently about an oinice of strong 

 sulphuric acid. The violent effervescence acts as a purge on 

 the shells, blowing out the softened contents, and liberating a 

 large quantity of sarcode flock. The acid also (which is in 

 great excess) dissolves the iron colouring-matter, making the 

 shells beautifully transparent. All that remains now to do is 

 repeated washing, during which process the shells can l)e 

 sorted. Thus, fill the precipitating-glass having the shells 

 in it with water, let stand for three quarters of a minute, and 

 pour the water into the second precipitating-glass; let the 

 second glass stand for two minutes, and throw away what still 

 remains suspended ; repeat this, and all the smaller shells will 

 find their Avay into the second glass, and all the larger ones 

 will remain in the first. If the large shells are not perfectly 

 clear, repeat the boil in soda, the acid, and the washing. 



