MS 



ANALYSIS OF OLIBANUM, 



Resin. 



Its properties. 



Action of al- 

 kalis on com- 

 mon resin. 



the eyaporation to dryness, a residuum was obtained, which, 

 when well washed and dried, furnished mucous acid, 

 amounting to a third of the weight bf the gum employed. 

 The waters of elutriation contained oxalic and malic acid, 

 but in small quantity. 



D. The alcoholic solution (A), evaporated to dryness, 

 yielded 14 gram. [216*2 grs.] of resin ; whence it follows, 

 that there was a loss of 2 gram. [3088 grs.], which I 

 ascribe in great part to the volatile oil. 



1. The resin of olibanum is of a reddish yellow colour; 

 it easily cracks on cooling, becomes very brittle, has no 

 perceptible taste, is electric when rubbed, and a good deal 

 resembles common resin. 



2. It softens in boiling water, but it requires a greater 

 heat to melt it. Exposed to flame, it burns, and emits a 

 smell thajt is not unpleasant. 



3. This resin, heated with a solution of caustic potash, 

 and evaporated to dryness, left a residuum not very solu- 

 ble, which, after being well washed, was diifusible in boil- 

 ing water, producing an emulsion. Common resin unites 

 much more readily with alkalis *. 



4. Sulphuric 



• Resinous substances have never yet been examined with the 

 minuteness and attejition they deserve, as appears from the few 

 facts collected respecting their chemical properties, and even of 

 these several are inaccurate. Many even suppose, that alkalis 

 have no action on resins; as a trial of which I made the following 

 experiments: 



Into a cold and very weak solution of potash I put common 

 resin powdered, by a little at a time. The result was a complete 

 soapy solution, which became thiols and ropy like the white of an 

 egg. The weakest acids occasioned in it a copious white sediment. 

 Alkalis and neutral salts do the same, in consequence of their 

 greater affinity for water. A large quantity of common water too 

 decomposes this soap, and the precipitate it occasions is but partly 

 soluble in alcohol. The part that refuses to dissolve in it still con-*- 

 tains a great deal of resin united with lime. 



If muriate of lime be added to this resinous soap, the mixture 

 lhit;kens into a whitish mass resembling pap, consisting of resin 

 and lime. 



All metallic solutions completely decompose the soap of resin, 

 and several of the precipitates tlius formed may be employed in 

 .painliug. 



Fifty 



