ON THE COMPOSITION OF BIED-LIME. 19 



considerable volimie, is of little weight. Cold alcohol scarcely dis- 

 solves it at all, and even hot alcohol, which has some solvent action 

 at first, attacks merely the surface-portion of the mass. The alcohol 

 solution deposits, as it cools, a nearly colourless, transparent, adhesive 

 matter, little ditferent from purified bird-lime itself. Ether is much 

 to be preferred to other solvents, because it yields a clear solution, 

 whereas carbon bisulphide and the rest give milky liquids, owing to 

 the presence of water. The ether solution mixed with alcohol be- 

 comes turbid and deposits a tenacious mass. 



Freed from water and particles of woody fibre, bird-lime under- 

 goes, when heated, scarcely any change up to about 350°, only becom- 

 ing slightly fluorescent and a little darker in colour, and acquiring a 

 feeble waxy odour. But about the melting point of zinc, it suffers 

 destructive distillation, in which most of it comes over as fatty acids 

 and fluorescent hydrocarbons of waxy and mild empyreumatic odour 

 and buttery consistence, very little permanent gas being formed, and 

 only a small carbonaceous residue being left. Bird-lime burns in the 

 air with a bright smoky flame. 



It is not very sensitive to reagents. Sulphuric acid dissolves it 

 slowly, forming a red liquid, which blackens only when heated, and 

 which gives, when poured into water, a viscid precipitate like bird- 

 lime, but dark coloured. Boilino- nitric acid of moderate strenîî^th 

 slowly dissolves it, with partial oxidation, this solution also precipitat- 

 ing with water. The sulphuric-acid solution poured into concentrated 

 nitric acid yields on addition of water a precipitate of a feebly nitrated 

 mixture of bodies. Aqueous solutions of potassium hydroxide only 

 slowly and slightly emulsify bird-lime. Fusion with the hydroxide 

 is attended with much darkening in colour and leaves a mass which 

 emulsifies in water. Potassium hydroxide in hot spirit slowly 

 dissolves the greater part of purified bird-lime, producing a dark-. 



