“ In a broad sense of the term, manufactures are such forms of industry as elaborate for economic use materials which are themselves the product of industry. Manufactures are thus distinguished from extractive industry, which procures wealth from nature in its primary forms. In practice it is difficult to draw a hard and fast line between these two types of industry, since many commodities which are commonly classed as raw materials have been subject to one or more elaborative processes, as, for example, raw cotton, raw sugar, pig iron. ”

“ The practice of American statisticians is to class with extractive industry processes which are directly connected with the exploitation of natural products. Butter and cheese which are made on the farm are treated as agricultural products; when produced in factories distinct from the farm they are classed with manufactures. A product in its earliest merchantable form may then be classed with raw materials; when subjected to further processes of elaboration it becomes a manufactured commodity. ”

“ The increase in the net product of manufactures above cost of material is not wholly a net increase in national income, although the greater part may be so regarded. It is further to be kept in mind that the statistics of capital are based upon estimates which in the nature of the case are not very reliable. ”