INTRODUCTION. 
below. In each class we shall deal with the natural sub¬ 
classes in turn, and in each of these deal first with group A, 
then with group B. 
It is almost needless to remark that in employing this 
classification products will not infrequently appear more 
than once under different classes. 
The Collection of Economic Products. 
Only in some cases can the products of plants be at once 
collected from them in a state fit for immediate use ; more 
often they require some preliminary treatment to put them 
into this condition. The kind of treatment, the methods 
employed in collection, and other similar points are dealt 
with below under the different classes of products. 
The placing of Economic Products 
The arts and manufactures require a large supply of raw 
materials of the most various kinds, belonging to the various 
classes described above. These materials are required in 
various forms, in regular supplies, and in varying quantities. 
They may be roughly divided, like those above mentioned, 
into important and minor products. The former are thJ 
basis of entire special industries or trades. They are in fact 
the indispensable articles of trade. The others are rather 
those which are rarely required, or which may be used as 
substitutes for the regular staples, or which may form the 
basis of new industries. These principles mast be carefully 
borne in mind by any one proposing to take np the produc- 
*r °! economic prodnct. If this prodnct be one of 
the established staples.it will beneedfnl f.rsnccess to place 
upon the market at least as good a quality at no higher 
and equal to the first samples. No manufacturer or user of 
