Apbil 9, 1909] 



SCIENCE 



573 



Tifacturers to make new and greater saving 

 in many raw materials other than fuel. 



Stream pollution by industrial refuse and 

 by sewage is a source of enormous waste in 

 our natural resources. The subject has been 

 for many years a field of research for indus- 

 trial, sanitary and biological chemists in the 

 United States, and their investigations have 

 resulted in the improvement of manufactur- 

 ing processes, the utilization of wastes, the 

 purification of sewage, and the protection of 

 domestic water supplies. "When the presence 

 of deleterious substances in our river and 

 lake waters has caused loss of fish life and the 

 destruction of oyster beds, the chemist and 

 the biologist have detected the harmful in- 

 gredients and have suggested methods for 

 their removal. River silt, an important 

 source of detriment to navigation, is also esti- 

 mated by the chemist. It has been fully 

 demonstrated that the prevention of stream 

 pollution . lies not alone through injunctions 

 and other legal proscriptions but also in using 

 waste materials or, when that is not possible, 

 in rendering them harmless. The chemist has 

 much to do in protecting and preserving the 

 quality of our water supply. Upon that, in 

 very great measure, depends the preservation 

 of our highest resource, human life. Pol- 

 luted waters distribute typhoid fever and other 

 dangerous diseases, and so cause losses which 

 should be, and really are, preventable. 



The foregoing illustrations are enough to 

 show, for present purposes, the intimate con- 

 nection between chemistry and the study of 

 conservation. They also bring out the fact 

 that the classification adopted by the national 

 commission, although admirable for statistical 

 research, is not final, and that it needs to be 

 supplemented by a different subdivision of the 

 data. The facts to be investigated often fall 

 under more than one heading of the classifica- 

 tion, and actually interlock in every conceiv- 

 able manner. To operate a placer mine, for 

 example, abundant water is needed, while 

 a deep mine requires timber for its shafts and 

 levels. In building and occupying a house 

 one covers land, uses lumber, brick, stone, and 

 iron, introduces water supply, and burns fuel. 



In short, every phase of the conservation 

 question affects the interests of everybody. 

 If the investigation of our natural resources 

 is to be made effective, it must be applied to 

 individual industries, and in order to do that 

 another scheme of classification would seem to 

 be necessary. Such a scheme we venture to 

 outline, but very briefiy. 



At the outset the problem can be divided 

 into two parts, one relating to sources of 

 energy, the other to material substances. 

 The two are not really separable, but may ad- 

 vantageously be considered separately. 



In the first place, the energy available for 

 industrial uses may be classified under three 

 heads, as follows: First, inexhaustible energy, 

 such as solar radiation, wind power, tidal 

 power and, with certain limitations, the 

 power furnished by flowing streams. Second, 

 reproducible or renewable energy, like the 

 power supplied by horses and other domestic 

 animals. Wood, regarded as fuel, also falls 

 under this heading, for forests can be artifi- 

 cially grown. Third, the exhaustible energy 

 represented by mineral fuel, like natural gas, 

 petroleum, and coal, which, once used, is gone 

 forever. Under this classification the prac- 

 tical problems are, to economize the exhaust- 

 ible energy, to encourage the development of 

 renewable energy, and to discover new methods 

 of using the inexhaustible energy. 



Exactly the same classification applies to 

 material substances. Some, like sea salt, 

 limestone and clay are, humanly speaking, in- 

 exhaustible. Agricultural and forest products 

 are reproducible, some of them year by year. 

 The metallic ores and such useful minerals as 

 phosphate rock are, however, exhaustible, and 

 need to be conserved. 



With the aid of this very simple classifica- 

 tion it becomes possible to analyze a specific 

 industrial problem in such a manner as to 

 make evident its factors of waste or economy. 

 For example, sea salt is inexhaustible, and 

 may be extracted by solar evaporation, which 

 is a use of inexhaustible energy. Agricul- 

 tural products are renewable, and their pro- 

 duction chiefly requires the renewable energy 

 of men and animals. But the smelting of 



