388 PRESERVATION OF AN HERBARIUM. 



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, with a little camphor, perfectly efficacious. 

 It is easily applied with a camel-hair pencil when the 

 specimens are perfectly dry, not before ; and if they 

 are not too tender, it is best done before they are pas- 

 ted, as the spirit extracts a yellow dye from many 

 plants, and stains the paper. A few drops of this so- 

 lution 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' experi- 

 ence, I can find no inconvenience from it whatever, 

 nor do I see that any dried plants can long be preserv- 

 ed 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 ad- 

 mitted, yet nothing can be more free than his collec- 

 tion from the injuries of dampness, or other causes of 

 decay. 



