Analysis of Birdlime. 133 



till they can be worked like paste : after this they are washed 

 in a stream of water, and kneaded together, so as to remove 

 all foreign matters. The paste is now deposited in earthen 

 vessels for four or five days, till it throws up a scum and 

 purifies. It is then put up in proper vessels, and is readv 

 for sale. 



This mode of preparing it is not generally adopted ; each 

 countv has its own process, and there are even some persons 

 who keep their method secret. 



AtNogent-le-Rotron birdlime is prepared from the shreds 

 of the second bark of the holly : it is allowed to ferment in 

 a moist place for fifteen days, and then boiled in water, 

 which is afterwards evaporated. 



At Coramercy and in its vicinity this substance is pro- 

 cured from different shrubs, as the holly, the vihurnum Ian- 

 tana, and themisletoe; from every difierent tree, such as 

 the apple, the pear, the lime, &c. 



The best is obtained from the prickly holly, and is of a 

 greenish colour : that which is made from the viburnum 

 lantana is yellowish. When this vegetable is employed, they 

 uniformly reject the epicrermis, and use only the second 

 bark. 



I prepared the birdlime which I used in my experiments 

 from the inner bark of the holly. On comparing it with 

 some which was made with great care, and sent me from 

 Commercy, I was unable to discover any sensible difference. 

 These precautions appeared to me necessary, that a greater 

 degree of accuracy might be given to the analysis. We well 

 know that the birdlime of commerce is seldom pure ; it is 

 often a mere nlixture of vegetable and animal matter, and 

 often adulterated with turpentine, oil, vinegar, &c.: it is 

 therefore absolutely necessary to ascertain previously the 

 purity of this substance ; and the process which 1 adopted 

 yielded me birdlime of the best quality. 



I took the inner bark of the holly, bruised it well, then 

 boiled it in water about four or five hours, and, having 

 thrown out the water, placed the bark in earthen pots under 

 ground : 1 allowed it to remain there till it putrefied, or 

 rather became viscid, taking care to sprinkle it with water 

 I 3 from 



