424 LATEX 



Constituents. The principal constituent of guttapercha is a hydro- 

 carbon, gutta, C 30 H 48 ; with this are associated several crystalline 

 substances which have been grouped into three series, viz. albans, 

 fluavils, and albanans. Guttapercha also contains tannin, salts, 

 substances resembling sugar, and an unstable substance, guttan. 



Gutta is white when pure, and has been obtained in minute crystals ; on 

 exposure to the air it gradually assumes a reddish colour. 



The albans are soluble in boiling alcohol, but not in cold ; they are crystalline 

 and are distinguished by the prefixes a, /?, y, &c. ; they yield by hydrolysis 

 with alcoholic potash the corresponding alcohol, albaresinol, together with 

 cinnamic acid. 



The fluavils are soluble in cold alcohol ; they are also crystalline, are simi- 

 larly distinguished, and yield an alcohol and cinnamic acid when saponified. 



The albanans are insoluble both in cold and hot alcohol. 



As the albans, &c., from different varieties of guttapercha are not identical, 

 these substances are further distinguished by a prefix indicating their source ; 

 thus those obtained from commercial (Sumatra) guttapercha are termed ' sum- 

 albans,' * suma fluavils,' &c. 



The quality of commercial guttapercha is judged by exhausting 

 with ether or petroleum spirit and determining the resins (albans, 

 fluavils, &c.) which dissolve, then removing the gutta with chloroform, 

 and weighing the insoluble residue. 



Uses. Apart from the varied technical uses of guttapercha a solu- 

 tion of that substance in chloroform is used to form a protective 

 covering on the skin or as a means of applying various remedies. 



Allied Drug. Balata is a similar substance obtained from Mimusops 

 globosa, Gaertner, by tapping and coagulating the latex either by 

 standing (sheet balata) or by boiling (block balata) ; it closely resembles 

 guttapercha both in physical characters and chemical composition. 



CAOUTCHOUC 



Source, &C. Caoutchouc is a substance contained in the latex of 

 a large number of plants, especially of those belonging to the natural 

 orders Euphorbiacece, Urticacece, and Apocynacece, but it is by no 

 means confined to these. Indeed, it is so widely distributed that in 

 all cases the latex of plants appears to contain caoutchouc or some 

 similar substance as a constant constituent. Many secrete it in such 

 quantity as to form suitable sources for its commercial extraction. 

 Commercial caoutchouc, however, always consists of caoutchouc 

 associated with fat, resin, &c., and is best termed ' rubber.' 



Para rubber, which is regarded as the best variety, is obtained 

 from Hevea brasiliensis, Miiller Argoviensis, and probably other species 

 (N.O. Euphorbiacece), a large tree widely distributed in the basin of 

 the Amazon and the low ground flanking its tributaries, the Madeira, 



