On drying Botanical Sjpecimetis. 393 



plants alike, and gets down into all the inequalities. We 

 should then dry rapidly, the sooner perhaps the better ; because 

 thus our specimens are best preserved, and the smaller the 

 heap is the sooner will the drying be accomplished. We 

 should change our paper occasionally. The time which 

 plants take in drying varies. Thin dry plants take no long time; 

 succulent ones much longer. By taking off the pressure occa- 

 sionally, and exposing our specimens to the air for a little, we 

 perhaps accelerate the drying ; although here we must be very 

 careful, some plants immediately shrivelling and withering. 

 Some plants we find so brittle as to bear no pressure ; by 

 leaving these exposed till they begin to wither, we find they 

 bear pressure well. Some pa;rts of a plant again will dry well, 

 others are so brittle that they must be left exposed for some 

 space. Some plants we find so retentive of life that weeks, 

 nay, months, will not suffice to destroy their vital powers; 

 some of these will then rot away, while others, strange to say, 

 will take root in the paper. Such refractory plants must be 

 immersed in hot water, which instantly kills them, then they 

 will dry easily. Some, however, will not bear this treatment ; 

 these must be rubbed over with a hot iron, while others must 

 even be boiled before they can be dried. Almost all of the 

 family of Orchideae, and many other plants, become quite black 

 by drying, while others dry very variously. Sea-weeds, it must 

 be observed, being often encrusted with the muriate of soda, 

 which is deliquescent, become moist in our herbariums, and 

 are thus often spoiled. These should be well washed in fresh 

 water before we attempt to dry them. Some plants with articu- 

 lated leaves will cast off their leaves in drying, these must be 

 glued on again. It is uniformly found, however, that plants, 

 even when perfectly prepared in this way, will, in the course of 

 years, lose their character and appearance very much, although 

 care and attention will long preserve them. Insects are very 

 destructive to our herbariums, especially the Ptinus i^ur, a 

 little beetle which lays its eggs in the receptacles of the flowers. 

 This, as well as other insects, is expelled or killed by the 

 solution of the muriate of mercury, which I have however 

 found, notwithstanding the assertion of Sir J. E. Smith to the 

 contrary, hurtful to several plants. 



Our specimens may be arranged under any system we choose. 

 That of Linnaeus is perhaps the best for a beginner, and is 

 the one which I always follow. Hoping that these few hints 

 may be acceptable to many of your readers, 



I remain, Sir, &c. 

 Edinburgh, May ^l. 1829. - W.D. 



