200 H. j. WADDINGTON ON THE USE OF AEABlN. 



rioration after a considerable time. It is undoubtedly a troublesome 

 and expensive matter to prepare, owing to the quantity of alcohol 

 required, but, when once obtained, a little of it goes so far that prac- 

 tically it costs little. Methylated spirit must not be used in its 

 preparation, as, containing always a proportion of shellac, or other 

 gum resins, this is sure to remain as an impurity. 



For use, a portion should be dissolved in distilled water to any. 

 required consistence, and passed twice through filter-paper, which 

 should have been previously washed with distilled water. It may 

 then be placed on the slips, drained, allowed to dry, and the slips 

 put away for use. In this condition, and with ordinary precautions 

 as to dust and damp, it may be preserved indefinitely. 



