SUBSTITUTES FOR NATURAL RESOURCES Any discussion of substitutes for natural resources must be prefaced by a discussion of the meaning of the term substitute. When whale oil was an important illuminant there was much concern as to its future supply and some search was made for possible substitutes. The development of the petroleum industry arose principally from a desire to find a use, in order to provide a market, for an available material and not in response to a search for a whale oil substitute. The electric light, which has so largely displaced the oil lamp, was developed as a demand for something better, not as a demand for a petroleum substitute, for the market has been almost continuously over-supplied with petroleum during the whole period of electric lighting develop ment. It is therefore possible to think of chinaware and porcelain as substitutes for the vessels of wood, horn and metal that pre ceded them ; of glass as a substitute for the oiled paper with which window openings were once closed ; of wooden houses as a sub stitute for skin tents; and of brick houses as a substitute for wooden ones. It is evident that these things are substitutes only in the sense that they replaced something that preceded them, and this because they better served some human need.
The term substitute has come to have a derived sense of some thing inferior used because that for which it is substituted either is not available in sufficient supply or, because of scarcity, is unduly high in price. The idea of the inferiority of the substitute is one that would be cultivated by those engaged in the production and marketing of the original. In the case of butter substitutes, for example, their production and sale are hampered by legislation which, it is alleged, represents the relative political strength of the interests involved rather than the scientific aspect of the matter. The converse of this situation is presented by various devices which are sold to provide an artificial substitute for the therapeutic effect of sunlight ; the producers of devices which give out infra-red rays are not required to furnish any evidence that the devices will produce the effects claimed for them. It will therefore be clear that the economic and social problems involved in the use of substitutes are many and varied. How difficult some of them are of solution can be illustrated by some examples.
Suppose a necklace of artificial pearls so skilfully made that only a few of the most expert persons in the world would be able to detect that they were not real pearls, which would cost io or ioo times as much as the substitutes. Has the belief in the inferi ority of the substitute any other than a sentimental basis? With inert natural resources the question is more easily de termined because the purposes which natural resources serve can usually be set forth in exact chemical and physical specifications. There can be no doubt whether one metal will conduct electricity as well as another, or whether one substance produces the same chemical effect as another for the kind and degree of difference can be measured, the cost can be ascertained, and the relation between the difference in the cost and the service studied. But even in the case of these substances it is sometimes difficult to make a just evaluation. A single substance may be used for a great many purposes, and thus is developed a tendency to carry over its known superiority for one use into another field where it may or may not be also superior. The general considerations in volved in this tendency are illustrated with specific examples. Tin is mostly produced in south-eastern Asia and Bolivia, where there is little local use for it, while the United States, which uses over half the world's total output, produces none. About one third of the metal imported into the United States is used for making tin-plate, and about two-thirds of the tin-plate is used for making tin cans for packing various commodities. The principal use of tin cans is for preserved foods. It is easily possible to pre serve food in ceramic ware jars, and many foods are sold in glass jars, but these jars are heavier and can easily be broken. For most purposes the glass jar is not, therefore, a satisfactory sub stitute for the tin can, but for specially selected fruits, which are to be sold at a high price, the glass jar is better, because the more attractive appearance of the jar is part of the consideration which enables it to be sold at a higher price. Thus glass is or is not a satisfactory substitute for tin in connection with food preserva tion, according to the special conditions attending its use.