ylnahj sis of Birdlime. 137 



The semi-vitreous oxide of lead acquires a gray colour, 

 dissolves, and forms a kind of plaster with this substance. 



Boiling alcohol, of forty degrees strength, dissolves bird- 

 lime: the solution is clear, transparent, and of a yellow co- 

 lour, but as it cools it becomes muddy. 



By the filter we can separate from the solution a yellow 

 matter which softens more readily than entire birdlime, and 

 which melts with a gentle heat ; diiTusing an odour very si- 

 milar to that of wax, which indeed it resembles in all its 

 characters. 



The filtered liquor is bitter, nauseous, and acid ; it lets 

 fall a precipitate by water, and leaves on evaporation a sub- 

 stance similar to resin. 



Sulphuric ether may be regarded as the true solvent of 

 birdlime : it acts upon this substance readily, divides, and 

 in the end dissolves it almost entirely, leaving a little vege- 

 table matter. The liquor assumes a greenish yellow colour, 

 and reddens strongly the tincture of turnsole. By the addi- 

 tion of a small quantity of water it becomes muddy, and the 

 ether rises to the surface ; but if the water be added in suf- 

 ficient quantity to dissolve the ether, a layer of oil exactly 

 similar to the oil of linseed forms on the surface : with the 

 semi-vitreous oxide of lead this last forms a plaster. 



The ethereal solution yields, by evaporation, a yellow 

 substance, vv'hich is greasy and soft like wax. 



Conclusion. 



From what has been now stated it must be very apparent 

 that little analogy exists between birdlime and glutinous 

 matter. 



A simple recapitulation will suffice to point out the proper 

 place which this substance ought to occupy among the pro- 

 ducts of vegetables. 



Birdlime is viscid and clastic ; it dries slightly by expo- 

 sure to llie air, and becomes brown, but never acquires the 

 briltlencss and unalterable properties of glue. 



It melts in the fire, inflames, swells up, and burns with 

 a bright flame ; but does not diflfuse that animal odour which 

 gluten is observed to do, 



^Vatef 



