72 TRANSITION OF INORGANIC INTO ORGANIC MATTER. 



The concrete sap is brown, firm, of an acrid and bitter taste, and 

 of a peculiar sickening odor. Opium contains a number of principles 

 the study of which has exercised for a considerable time the inge- 

 nuity of the most skilful chemists. It was in this substance that 

 Sertuerner found the first vegetable alkali which was discovered, 

 morphine. After numerous trials made on opium, it was found to 

 contain : — 1. Morphine, (vegetable alkali.) 2. Codeine, (the same.) 

 3. Narceine. 4. Meconine. 5. Para-morphine. 6. Pseudo-mor- 

 phine. 7. Meconic acid. 8. Resin. 9. Fatty matters. 10. Caout- 

 chouc. 11. Gum. 12. Bassorine. 13. Ulmine. 14. Woody sub- 

 stance. 15. Mineral salts with bases of lime, magnesia, and potash. 



MILK OF THE PLUMERIA AMERICANA. 



The plumeria, 'when one of its branches is broken, yields a con- 

 siderable quantity of milky juice. At the time when I examined 

 this juice, the tree was entirely destitute of leaves. The milk of the 

 plumeria is perfectly white ; it is very fluid when it flows from the 

 plant, but soon after deposites a crystalline sediment. The taste is 

 slightly bitter, and it has an acid reaction. The milk of the plumeria 

 appears to contain no animalized matter. I was only able to detect 

 a very large proportion of resinous matter held in solution or sus- 

 pended in water ; and indications of potash, lime, and magnesia, 

 combined with an organic acid. 



SAP OF THE CAOUTCHOUC TREE. 



Caoutchouc is found in the sap of many trees, and in that of a 

 great number of herbaceous plants ; but it is the havea caoutchouc, 

 the jatropha elastica, peculiar to South America; the ftcus Indica, 

 and the artocarpus integrifolia, which grow in the East Indies, that 

 yield the caoutchouc so well known in commerce, and which has 

 been converted to so many useful purposes in the arts. 



The caoutchouc tree is particularly common in Choco and forests 

 near the equator. To obtain the elastic gum, the Indians incise the 

 tree below the bark, when there issues a copious discharge of milky 

 sap, which will remain fluid for a considerable lime, if it be kept 

 from contact with the air. I have seen it carried to great distances, 

 in wooden vessels hermetically closed. When spread out in thinnish 

 layers, it soon coagulates, and acquires the singular elasticity which 

 characterizes caoutchouc. The action of the oxygen of the air may 

 possibly have some influence in producing this coagulation, un- 

 less what I am about to state be the effect of a prompt evaporation 

 of the water of the sap. I have often made a small incision in the 

 trunk of an hcEvea from which milk immediately flowed, and by rea- 

 son of its viscidity, trickled down the tree in a stream of a certain 

 thickness ; this milk was at first extremely fluid, but after from one 

 to two minutes' exposure to the air, it suddenly coagulated, so that 

 on raising the drop from the lower end, I obtained a long string or 

 riband of perfectly elastic caoutchouc. 



