546 COLLECTING AND PRESERVING SPECIMENS 



The specimens are now ready to be filed away on shelves in a horizon- 

 tal position. If insects attack the specimens, they may be destroyed 

 by fumes of bisulfid of carbon (see page 293) or chloroform. The 

 bisLilfid treatment is probably the best yet devised, particularly for 

 large herbaria. In this case it is necessary to place the specimens in 

 a tight box and then insert the liquid. Lumps of naphthalin placed 

 in the cabinet are useful in keeping away insects. 



Various poisons have been used on herbarium plants. At one time, 

 the Gray Herbarium used an arsenic solution, but this proved to be 

 injurious to curators. Three corrosive sublimate (bichloride of mer- 

 cury) recipes are as follows : — 



1. Place as much corrosive sublimate in alcohol as the liquid will 

 dissolve. Apply with a brush, or dip the plants before they are 

 mounted and dry them between sheets. A common method. 



2. Dissolve If ounces of corrosive sublimate in one pint of alcohol ; 

 add 2^ fluid drams of carbolic acid, and apply with a paint brush. 



3. One pound of corrosive sublimate, one pound of carbolic acid, to 

 4 gallons of wood alcohol. 



Preserving, Printing, and Imitating Flowers and Other Parts of Plants 



To Preserve the Color of Dried Flowers. — 1. Immerse the 

 stem of the fresh specimen in a solution of 32 parts by weight of alum, 

 4 of niter, and 186 of water for two or three days until the liquid is 

 thoroughly absorbed, and then press in the ordinary way, except that 

 dry sand is sifted over the specimen and the packet submitted to the 

 action of gentle heat for twenty-four hours. 



2. Make a varnish composed of 20 parts of powdered copal and 500 

 parts of ether, powdered glass or sand being used to make the copal 

 dissolve more readily. Into this solution the plants are carefully 

 dipped ; then they are allowed to dry for ten minutes, and the same 

 process is repeated four or five times in succession. 



3. Plants may also be plunged in a boiling solution of 1 part of 

 salicylic acid and 600 of alcohol, and then dried in bibulous paper. But 

 this should be done very rapidly, violet flowers especially being decolor- 

 ized by more than an instantaneous immersion. 



4. Red flowers which have changed to a purplish tint in drying may 

 have their color restored by laying them on a piece of moistened paper 



