On Preserving Organic Specimens. 339 



My plan consists in wholly abstracting the moisture from the 

 specimen to be preserved, having previously inclosed it in some 

 material impervious to air or moisture, in order that the condition 

 of absolute dryness may be perpetually maintained. The desic- 

 cative substance which I make use of, is unslacked lime ; and 

 though other agents might be used, this seems to answer in all 

 cases so perfectly well, as to leave nothing to be desired. Pure 

 quick lime, it is well known, will absorb near one third its weight 

 of water in the process of slacking, yielding a powder apparently 

 as free from moisture as at first. 



I will first explain the manner in which botanical specimens are 

 to be framed for constant exposure on the walls of a museum or 

 lecture room. 



Take a specimen, recently dried in the usual way, between 

 folds of bibulous paper, in order that every shade of color may be 

 natural and fresh as life ; procure a pane of glass of sufficient 

 size, and a plate of tin, zinc, copper, or sheet lead,* half an inch 

 longer and half an inch broader than the pane of glass ; bend 

 this around the edges so that it will embrace the glass ; remove 

 the latter, and place in the shallow cavity a thin layer of cotton 

 batting; upon this, sift a thin stratum of the powder of quick 

 lime; over this another layer of batting; upon this a sheet of 

 tissue paper, and on the tissue paper, the specimen and label. 

 Over all, place the clean pane of glass ; press it gently down, 

 and carefully turn over it the edges of the metallic plates. Se- 

 cure the junction of the glass and metal with a ceroid or resi- 

 nous cement, as bees' wax, shellac, or sealing wax : or what is 

 more convenient, and seems to answer well, fill the crevices with 

 stiff glazier's putty, and when that gets dry, pass over it with 

 thick Japan varnish, of which two or three successive coats may 

 be used. If the back be of sheet tin, zinc, copper, or thick sheet 

 lead, a ring may be soldered to one end, for the purpose of hang- 

 ing up without further preparation. But if very thin sheet lead 

 be used, it may require to be first protected by a back of binder's 

 board and some kind of frame. 



With a view of subjecting theory to the test of experiment, I 

 enclosed in this manner a dried specimen of Lycopodium apodum, 

 and also attached a part of the same specimen by means of stick- 



* The sheet lead which lines tea boxes answers very well. 



