T. Kikk. — On the Preparation of Botanical Specimens. 323 



length of each layer being regulated by the length or width of 

 the drying-papers. The bars should be laid about 2in. or 2^in. 

 apart, one layer crossing the other at a right angle, the whole 

 being secured by wire nails ac the points of intersection. A. 

 press arranged with ventilators on this plan does not require 

 such frequent changes of paper, as much of the moisture is 

 drawn off by air-currents passing through the ventilators, the 

 amount largely depending upon the state of the atmosphere. 

 In wet weather ventilators are of but little value. Sometimes 

 the ventilators are made of woven wire strengthened by a 

 marginal iron frame, but, except for outside covers, the results 

 are less satisfactory than with the wooden ones previously 

 described. A press of this kind may be placed in an open 

 window with advantage. 



The process of drying may be shortened by placing the 

 press in a large oven, by using hot drying-papers, or by pass- 

 ing hot flat-irons over the separate layers of specimens. 



The time requisite for preparing really good specimens, and 

 the frequent changes of drying-papers required, have led to 

 many attempts to discover some improved process, but the 

 results have not been altogether satisfactory : still, two of 

 these processes deserve brief mention. 



Rather thick absorbent brown paper may be saturated 

 with chloride of lime in solution. The sheets should then be 

 dried in an oven, and enclosed in a perfectly air-tight box 

 until wanted for use. The specimens should be laid in folded 

 sheets of any thin paper, which should be placed between the 

 prepared drying-papers, pressure being given by straps and 

 buckles, when the press should be placed in an air-tight box, 

 or protected from the atmosphere by being wrapped in oiled 

 cloth. Ordinary specimens do not require more than a single 

 change of drying-papers, and become "thoroughly dry in a few 

 days, the colour being well preserved ; but, as a rule, speci- 

 mens prepared in this way are very brittle. The drying- 

 papers can only be deprived of absorbed moisture by being 

 placed in an oven, and care must be taken to keep them fit for 

 use by preventing the access of air as completely as possible. 



A more advantageous process is to saturate water with 

 sulphurous acid ; then to add methylated spirit in the pro- 

 portion of one to three. Thick-leaved plants, such as the 

 larger species of Cclmisia, &c, should be soaked in the fluid 

 from twelve to twenty-four hours, according to the succulence 

 of the leaves and stem. Plants with still thicker leaves may 

 require from one to two days ; while delicate and thin-leaved 

 plants should only remain in the liquid from five minutes to 

 an hour. It is imperative that all external moisture be re- 

 moved by wiping or by exposure to dry heat before the 

 specimens are placed in the press. Thin-leaved plants 



