Organic Remains, Crystals, and Artificial Objects. 97 



While we look, they have grown imperceptibly, and 

 new ones have joined them ; presently all the edges of 

 the drop are crowded with these brilliant little books, 

 pink, green, blue, orange, and other fine colours. 

 Suddenly there come down upon them certain long 

 keen sabre-like crystals, which we may liken to paper- 

 cutters : this occurs when the film is nearly dry. 



Dr. Carpenter's and other works give the names 

 of a great number of crystals suitable for microscopic 

 observation. Eeferring the reader to these, I shall 

 now only describe the arrangement which I have 

 found satisfactory for displaying them. A reader 

 happy enough to have a considerable knowledge of 

 chemistry will easily find out how to vary the experi- 

 ments. 



Such a reader will very probably have various 

 little appliances at hand preferable to those which I 

 describe; mine may, however, be commended as 

 answering their purpose, and enabling the exhibitor 

 to avoid disfiguring stains from the nitrate of silver. 

 To proceed, then ; the various solutions, of which a 

 small teaspoonful will be quite sufficient to prepare, 

 may be made in one of those colour-trays generally 

 accompanying paint-boxes, and containing half-a- 

 dozen hollows. It is well to write neat little labels, 

 and gum one near each hollow, say "nitr. silver/' 

 " sulph. copper/' ' ' sugar of lead/' ' ' saltpetre," ' ' mu- 

 riate amm." You should have at hand a bottle of 

 rain-water, a few slips of glass of the usual size, and 

 some narrow pieces of glass, or glass rods ; also two 

 or three rags, one as a complete drudge to wipe off 



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