C 73 ] 



from the misletoe, from gummastic, opium ^ and from 

 the berries of the Smilax caduca, in which last plant it 

 has been lately discovered by Dr. Barton. 



Gum elastic, when distilled, affords volatile al- 

 kali, water hydrogene, and carbon in different com- 

 binations, It therefore consists principally of azote, 

 hydrogene, oxygene, and carbon ; but the proportions 

 In which they are combined have not yet been ascer- 

 tained. Gum elastic is an indigestible substance, not 

 fitted for the food of animals ; its uses in the arts are 

 well known. 



7. Extract, or the extractive principle, exists in 

 almost all plants. It may be procured in a state of 

 tolerable purity from saffron, by merely infusing it in 

 water, and evaporating the solution. It may likewise be 

 obtained from catechu, or Terra japonica, a substance 

 brought from India. This substance consists princi- 

 pally of astringent matter, and extract ; by the action 

 of water upon it, the astringent matter is first dissol- 

 ved, and may be separated from the extract. Extract 

 is always more or less coloured ; it is soluble in alcohol 

 and water, but not soluble in ether. It unites with alu- 

 mina when that earth is boiled in a solution of ex- 

 tract , and it is precipitated by the salts of alumina, 

 and by many metallic solutions, particularly the solu- 

 tion of muriate of tin. 



From the products of its distillation, it seems to 

 be composed principally of hydrogene, oxygene, car- 

 bon, and a little azote. 



There appears to be almost as many varieties of 

 extract as there are species of plants. The difference 



