60 ETON NATURE-STUDY 



remain attached to the specimens is brushed away with the utmost 

 care. A modification of the process may be made by using hot sand, 

 and by this means advantage is gained, as the more rapid the drying 

 of some parts the better the colours are retained, though the plants 

 are more brittle afterwards. 



Sand is not by any means, however, the only material used for the 

 purpose. A mixture of one part of lime to three parts of plaster of 

 Paris may be employed. Experiments ought to be made with a 

 number of substances, as improvements are possible. For instance, of 

 recent years the British Botanical Association has produced very success- 

 ful work (see figures 181 and 182) with the earth (kieselguhr), which, 

 when saturated with nitro-glycerine, forms dynamite. The earth is, 

 however, subjected before its use with plants, to a special treatment, 

 the details of which have not been made public. What is required, is 

 a material or mixture which has the necessary weight combined with 

 sufficient powers of absorbing moisture, and which does not stick 

 unduly to the leaves and flowers. The specimens may be stitched to 

 cards and kept in glass-topped boxes with tightly fitting lids. A 

 more expensive method, more suitable perhaps for museums, is to 

 place the dried plants in glass jars with hollow stoppers in which 

 calcium chloride is placed, which will absorb all the moisture from 

 the air in the jar and keep the specimen perfectly dry.* In this case 

 the colours preserved in sand will keep for a very long time. 



If the older method of pressing flowers be adopted, care should be 

 taken to choose a form of press which allows of the free entrance of 

 air,* and the drying paper should be frequently changed. When the 

 plants are mounted they should not be stuck permanently to cards, 

 but attached by strips of gummed paper or stitches, so that they can 

 be placed on clean backgrounds at any time. Care should be taken 



* See Appendix. 



