BOTANY. 163 



and empty sheets, and then press the whole be^ 

 tween the planks with the straps, arid expose them 

 in a dry, warm, and airy place. We ought every 

 day to change the damp paper for dry, until the 

 desiccation is completed. We may shorten this 

 operation a little, by only changing the intermediate 

 sheets, and always leaving the plant in that in which 

 it was first placed ; but in this case the number of 

 intermediate sheets must be more considerable. 

 When we plunge saponaceous plants, lilacese, or*> 

 chideae, &c. into hot water to destroy their vitality, 

 we must always except the flowers; and after this pro- 

 cess, we must be very careful to change their papers. 



Very delicate aquatic or marine plants require 

 peculiar care : we must float them in a basin of 

 fresh water, and then pass under them a piece of 

 very strong white paper, by which we raise them 

 slowly and obliquely, that the plants may remain 

 attached in their natural position. If the plants 

 are extremely delicate, we must use talc or glass. 



When the fruits are of a dry nature, it is often 

 more advantageous to leave them in their husks 

 without sifting them ; but when the fruit is fleshy, 

 we must separate them. 



When fruits are dry and coriaceous, they do not 

 require any other preparation than being preserved 

 in a dry place, not exposed to the sun: and those 

 whose valves open with desiccation, must be tied 

 round with a piece of strong thread. 



