380 UnMa-'IRubber Culture fn /iDejtco. 



is 0.925, but when pressed out like cream it contains 32 per cent, of the 

 liquid. 



From the analysis made by Prof. Faraday, rubber, as it flows from 

 the trees, is composed as follows: 



Water with a little free acid 56.37 



Rubber or caoutchouc 3 J -7 



Albumen 1.90 



Wax 



A body of nitrogen soluble in water 7.13 



A substance insoluble in water 2.90 



100. OO 



According to the same scientist, rubber already dry contains none 

 of the oxygen which is found in most vegetable products, but is an 

 hydrocarburet consisting of eight parts of carbon and seven of hydro- 

 gen, which would require a proportion of 82.27 f carbon to 12.73 f 

 hydrogen for every 100 parts. The quantities found by him were 

 87.02 of carbon to 12.08 of hydrogen. The same result was obtained 

 in the analysis made by Dr. Ure. 



In his Dictionary of Arts, Manufactures, and Mines, Dr. Ure ob- 

 serves that rubber, in its liquid state, that is, " cachusina," which is 

 formed by the distillation of the rubber, has less specific gravity than 

 sulphuric ether; while in its fluid condition, it is heavier than the 

 heaviest of all gases. 



He remarks also, that the greater part of the rubber imported to 

 Europe came formerly from Para, in Brazil, but that in recent years 

 great quantities have been received from Java, Penang, Singapore, 

 and Assam, 



According to M. de la Condamine, rubber is extracted chiefly 

 during the rainy season, because at that time the trees yield more 

 abundantly than in the dry season. 



Mr. Lee Norris, of New York, discovered the means of keeping 

 rubber in its milky form, as it flows from the tree, in hermetically 

 sealed vases; the liquid is first filtered, then well mixed with the 

 eighteenth part of its weight of strong ammonia. When poured on a 

 plane surface and exposed to a temperature between 70 and 100 de- 

 grees Fahrenheit, the ammonia that protected it from the action of the 

 oxygen in the atmosphere evaporates and leaves the rubber, which re- 

 mains white, and in the shape of its container. 



Vulcanized rubber, a combination of rubber and sulphur, was first 

 made by Mr. Charles Goodyear, of New York, to whom letters-patent 

 for his invention was granted in February, 1839. Mr. Goodyear made 

 further experiments later on with sulphur, lead, and rubber, but these 

 did not give as satisfactory results as the first ones. 



