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tan bark are also to be sought for by means of chemical investi- 

 gations. Another distinctly chemical operation is the preparation 

 of wood pulp for paper making, a process which is now wasteful 

 in the highest degree. It is estimated that for every ton of pulp 

 now made by the sulphite process more than a ton of waste ma- 

 terial is allowed to drain away into our streams. How to make this 

 material useful is a chemical problem, and so also, in great part, 

 is the investigation of other, now useless fibers, which may replace 

 the more valuable wood. The preservation of wood from decay 

 is still another art in which chemistry is predominant. 



" In preserving the fertility of our land, chemistry has an im- 

 portant part to play. Our knowledge of fertilizers, of the food 

 on which crops can thrive, is entirely chemical so far as accuracy 

 is concerned, and must be applied in accordance with chemical 

 principles. A fertilizer which is useless, and therefore wasted on 

 one soil, may be needed on another. Certain fertilizers, like the 

 Stassfurt salts, Peruvian guano, the Chilean nitrates, and phos- 

 phate rock are limited in quantity, and their future exhaustion 

 must be considered now. What shall replace them in the future? 

 Already processes have been devised for fixing the nitrogen of 

 the atmosphere and rendering it available for plant food. Salt- 

 peter and other nitrates can be and long have been made from 

 waste materials such as old mortar and animal refuse. The phos- 

 phatic slags have been mentioned in connection with metallurgi- 

 cal processes. These sources of fertility are important, but 

 greater still is the source found in our municipal sewage. The 

 problem of its salvage has been worked out in some localities, 

 but in the United States the people are only beginning to be 

 aroused to its importance. Enormous masses of material, easily 

 available for fertilizing purposes, now drain into our rivers or 

 directly into the sea. Another question, now under investigation, 

 is the possibility of using our common feldspathic rocks in fine 

 powder, to replace the potassium withdrawn by plants from the 

 soil." 



