084 



it greatly siiri)asscs in durability and tenacity in a damp state. The paper is impreg- 

 nated with the salt by dipping it (a sheet at a time) in a solution formed by dissolving 

 13i oz. of the crystallized chloride of calcium in one (imperial) 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 contain- 

 ing it should be capable of holding seveml times the quantity, on account of ebulli- 

 tion. After saturation the liquid should be filtered, and diluted with water till its 

 specific gravity falls to 1"188 ; this may be ascertained most readily by a glass bead of 

 that number. The sheets as they are dipped (a large tea-ti'ay is very convenient to 

 hold the liquid) should be carefully laid one upon another, and at length so much li- 

 quid pressed out that they will not drip when held before a fire to dry. I diy them 

 before a fire, but a friend suggests that much time and trouble would be saved by dry- 

 ing 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 ap- 

 plied 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 pieces of flannel ; of course the same surface of the cotton or 

 flannel should always be applied to the paper, to prevent communication of the salt 

 to the plants. I have prepared some sheets of paper on one side only, but have not 

 yet given them a trial. The pads do not much afiiect the quick drying, but they pre- 

 serve soft parts from injury, and render a very slight pressure sufiicient. When I wish 

 to preserve the corolla of a plant in the best possible manner, I place iinder and above 

 it a little finely opened cotton wool. When very watery plants are to be dried, such 

 as Hotionia palustris, I would place an extra cushion of cotton wool over them. 

 Plants seem to dry best at a temperature of about 100" Fah. When the papers have 

 taken up as much moisture as they can absorb, they may be re-dried before a fire, if 

 the method suggested by a friend (drying at a baker's oven) should not be accessible. 

 Orchidaccw and Scroplmlariacece are bad driers, even with the aid of chloride of cal- 

 cium ; but I find that Listera ovata, and probably some others, may have their colour 

 perfectly preserved if immersed for a few seconds in a nearly boiling but very weak 

 solution of carbonate of soda, then wiped and placed between the papers. This re- 

 mark may perhaps induce some one with more leisure than myself to experiment on 

 various ways of drying plants of these natural orders. 



" The disadvantages of the method are, in my opinion, inconsiderable when com- 

 pared with the saving of time and trouble, and the much better preservation of the 

 specimens. Brown paper is not expensive. Crystals of chloride of cdcium may be 

 bought of the Liverpool Apothecaries' Company, and perhaps elsewhere, at od. per ib., 

 or if prepared at home, the expense will be about the same. The cotton-wool cush- 

 ions cost Id. or Isd. each ; flannel is more durable, but more expensive. The cushions 

 render the apparatus bulky, but this is only an inconvenience iu travelling, and then 

 the far greater inconvenience of drying papers^ at inns in the summer mouths is ex- 

 perienced about once in three weeks instead of once a day, or every other day. Such 



