

% 



CHAPTEK III. 



INFERIOR GUMS AND RESINS. 



Gum laCj or shellac. Pine and other fir-tree gums. Bitumen of various kinds — asphaltum, 



coaltar, &c. 



It is not the intention of the author at present, to enter into a 

 detailed history of the numerous gums and resins which, from 

 their connection with these improvements, it is obvious might 

 very properly be treated of in connection with the history of 

 gum-elastic. It would be desirable, and it is the author's inten- 

 tion, at a future time, to give a more particular account of them, 

 as well as minute recipes for the different proportions and mix- 

 tures, by which they are made to answer their distinct uses in 

 perfecting the vulcanized compounds and fabrics of gum-elastic. 



The term inferior is used chiefly for the sake of distinction. 

 They are not, strictly speaking, inferior, except in the property 

 of elasticity. Those of them that are known in commerce, have 

 each their separate uses, the importance of which is well known 

 in manufactures and the arts ; they may, however, be styled in- 

 ferior as relates to the inventions treated of in this work, for the 

 reason that although the perfection of many of the fabrics and 

 compounds depends upon some one or more of these gums, yet 

 none of them separately will fill the place or answer the uses 

 peculiar to gum-elastic, for the want of its elastic property, 

 while India rubber will answer these uses when vulcanized, in- 

 dependent of other gums or resins, although, in some cases, it 

 answers a better purpose in combination with than without 

 them. 



■e^S 



