134 Analysis of Birdlime. 



fropi time to time. When this process was completed I 

 washed it, so as to remove all foreign matters. 



II. Chemical and Pliysical Properties of Birdlime. 



Birdlime has a greenish colour; its taste is bitter: it is 

 glutinous, ropy, and tenacious ; its odour resembles that of 

 linseed oil. 



When spread upon a plate of glass, and exposed for some 

 time to the an- and light, it dries and becomes brown. In 

 this state it is no longer viscid : when it is completely dried 

 it may be reduced to powder; it has then lost all its gluti- 

 nous properties, and it cannot rcsui^ie them by the additioia 

 of waler. 



Birdlime reddens the tincture of turnsole. When heated 

 alone in a porcelain cup it melts without becoming very li' 

 quid ; it swells up and forms bubbles, which rise to the sur- 

 face and then buist. This kind of fusiori discovers small 

 black grains, which give it an uneven appearance : it diffuses 

 an odour verv similar to that of the fat oils when their tem- 

 perature is raised. 



If the birdlime be kept in fusion for some time, it ac- 

 quires abrowir.sh colour; but again resumes all its proper- 

 ties on cooling. When placed upon red embers it burns 

 with a flame, and emits an abundance of smoke. 



Heated in a crucible of platina, it burns as soon as the 

 crucible becomes red. Its flame is bright, and rises above 

 seven inches : it is attended with a considerable quantity of 

 smoke, which is readily condensed upon the vault of the 

 chinmcv. The combustion continues even after the crucible 

 is removed from the fire. There remains a white cinder, 

 which is very alkaline, and partly soluble in water. By the 

 use of re-agents we ascertain the presence of sulphate and 

 muriate of potash. 



The portion which is insoluble in water, when treated with 

 the muriatic acid, dissolves with effervescence. 



The solution is copiously precipitated by the oxalate of 

 annnonia; prussiate of potash produces a blue precipitate; 

 and with amn:onia it lets fall a matter of a pasty consist- 

 pncej which is partly soluble in caustic potash : from these 



factg 



