INTRODUCTION. 
Miscellaneous products—gums, resins, caoutchoucs, 
alkaloids, balsams, camphors, dyes, tannin, 
Our knowledge of the chemistry and physiology of the 
plant is hardly as yet sufficiently advanced to enable us to 
form a good natural classification of economic products on 
the above basis. We are therefore compelled for the present 
to adopt a somewhat artificial grouping of the products 
with which we have to deal. In the Dictionary of Indian 
Economic Products and in the Agricultural Ledger 
Dr. Watt has adopted such a grouping, and for convenience 
of cross reference to Indian work it will be advisable to use 
a similar classification for Ceylon. This is in fact already 
employed in filing information at Peradeniya. 
The principal products of the vegetable kingdom are 
grouped into eight chief classes, thus:— 
i, caoutchoucs, guttaperchas, and c 
II.—Oils and fats. 
III.—Dye stuffs and tanning substances. 
V.—Drugs and medicinal products. 
VI.—Edible products. 
VII.—Timbers. 
VIII.—Miscellaneous products and useful plants. 
It is obvious that further subdivisions are required in 
each class, partly natural, partly artificial. Thus, the first 
class may be naturally divided into gums, resins, caout¬ 
choucs and guttas, camphors, &c., the second into fixed oils 
and essential oils, and so on. For practical purposes we 
may make a further division, purely artificial, into important 
products or staples and minor products, terming these 
groups A and B respectively. This system will be used 
