524 USE OF AN HERBARIUM. 



scarcely be thoroughly dried, before it is devoured. Ferns are 

 scarcely ever attacked, and grasses but seldom. To remedy this 

 inconvenience, I have found a solution of corrosive sublimate of 

 mercury in rectified spirits of wine, about two drams to a pint y 

 with a little camphor, perfectly efficacious. It is easily applied with 

 a camel-hair pencil when the specimens are perfectly dry, not be- 

 fore ; and if they are not too tender, it is best done before they are 

 pasted, as the spirit extracts a yellow dye from many plants, and 

 stains the paper. A few drops of this solution should be mixed with 

 the glue used for pasting. This application not only destroys, or 

 keeps off all vermin, but it greatly revives the colours of most 

 plants, giving the collection a most pleasing air of freshness and 

 neatness. After several years' experience, I can find no inconveni- 

 ence from it whatever ; nor do I see that any dried plants can long 

 be preserved without it. 



The herbarium is best kept in a dry room without a constant 

 fire. Linnaeus had a stone building for his museum, remote from 

 his dwelling-house, into which, I have been told, neither fire nor 

 candle was ever admitted ; yet nothing can be more free than his 

 collection from the injuries of dampness, or other causes of decay. 

 [Smith's Introduction to Physiological and Systematical 

 Botany* 



