Mr. J. J. Murcott on drying Plants for the Herbarium, 33 



X.— On drying Plants for the Herbarium by means of a 

 Deliquescent Salt. By J. J. Murcott^ Esq.* 



The plants to be dried are placed between sheets of paper contain- 

 ing chloride of calcium, contact with the salt being prevented by an 

 intervening cushion on one side, and a layer of fine calico on the 

 other. Two thin boards support the apparatus, and are held together 

 by a couple of buckled tapes ; the whole is enveloped in oil cloth to 

 exclude atmospheric moisture. The packet need not be opened till 

 the plants are dry enough to be removed, or fresh plants require to 

 be introduced. The time and trouble of frequently removing drying 

 plants into fresh papers, as in the ordinary method, are both saved ; 

 for though the packet be full of plants, it need not be opened even 

 for several months. Plants in general dry much faster than in blot- 

 ting-paper, and their colours are much more frequently preserved : 

 the use of the pad prevents injury to the soft parts of plants, and 

 hinders their corollas from shrivelling up in drying, without apply- 

 ing so much pressure as would unfit any part for subsequent exami- 

 nation. 



Brown paper, so thick as to prevent the transmission of light, 

 with a smooth surface, and not much sized, is better fitted to hold 

 the salt than blotting-paper, which it greatly surpasses in durability 

 and tenacity in a damp state. The paper is impregnated with the 

 salt by dipping it (a sheet at a time) in a solution formed by dis- 

 solving 13joz. of the crystallized chloride of calcium in one (im- 

 perial) pint of water. Where the chloride is expensive, or difficult 

 to be procured, it may be prepared by saturating hydrochloric acid 

 with fragments of marble, or even with common chalk : the acid 

 may be of commercial strength or slightly diluted with water ; but 

 the vessel containing it should be capable of holding several times 

 the quantity, on account of ebullition. After saturation the liquid 

 should be filtered, and diluted with water till its specific gravity falls 

 to T188; this may be ascertained most readily by a glass bead of 

 that number. The sheets as they are dipped (a large tea-tray is 

 very convenient to hold the liquid) should be carefully laid one upon 

 another, and at length so much liquid pressed, out that they will not 

 drip when held before a fire to dry. I dry them before a fire, but a 

 friend suggests that much time and trouble would be saved by 

 drying them in a baker's oven. A solution of this strength will 

 communicate as much of the salt as the paper can retain without 

 showing an exudation on its surface when applied to use and its 

 complement of moisture absorbed, while the excessive brittleness 

 occasioned, if the liquid be much more concentrated, soon splits the 

 back of every sheet ; and the drops of liquid that appear as the paper 

 grows very damp might deter a beginner from following the method. 



In applying the paper to use, I place about three sheets between 

 every lot of plants : the plants do not touch the paper but lie on a 

 cushion of cotton wool, and are covered with a piece of ' glazed 

 lining ' calico, or similar material ; or they are placed between two 



* Read before the Botanical Society of Glasgow, November 1842. 

 Ann. ty Mag. N. Hist. Vol. xi. D 



