NOTEMBEB 22, 1907] 



SCIENCE 



691 



light whicli the more accurate and rational 

 methods of science might furnish. They 

 had been educated in the school of experi- 

 ence, in which they learned that the closest 

 attention, the most arduous labor and the 

 strictest economy were demanded to extort 

 from their impoverished soils enough to 

 sustain themselves and families. But not 

 only this. The views of Liebig spread 

 rapidly all over the civilized world, and 

 aroused an enthusiasm among scientific in- 

 vestigators in every civilized country, rare- 

 ly equaled in the annals of history. It is 

 impossible in the time allotted to this paper 

 to go into detail. Suffice it to say that the 

 combined efforts of all these investigators 

 have done more for public welfare than 

 perhaps any other human undertaking. 

 Among the important results of their labors 

 in connection with soil and vegetable pro- 

 duction may be mentioned: 



1. The chemical composition of agricul- 

 tural products, including the ash or mineral 

 ingredients. 



2. The chemical composition of soils, 

 showing that the soil contains certain ele- 

 ments which serve as plant food and with- 

 out which vegetable growth is impossible. 



3. The establishment of the fact that the 

 most important of the ingredients of plant 

 food, i. e., those which furnish the bulk of 

 the ash of agricultural crops, and contained 

 in the soil in comparatively small quanti- 

 ties, that they are present in two forms, 

 available and reserve plant food, that the 

 immediate fertility of soils depends upon 

 the former, and that by continuous crop- 

 ping without application of fertilizing ma- 

 terials to the soil this available plant food 

 is gradually exhausted, until maximum or 

 even average crops can no longer be pro- 

 duced. 



4. The important observation that if 

 only one of the essential elements of plant 

 food is wanting in the soil, while all others 



are present in ample quantities, plants will 

 refuse to grow. 



5. The devising of methods by which the 

 wanting ingredients of plant food can be 

 definitely determined in an exhausted soil, 

 so that the loss of money and labor in ap- 

 plying fertilizers, which would have no 

 beneficial effect upon the production of 

 crops, can be avoided. 



6. The discovery and analysis of natural 

 deposits of plant food, as Guano, Chili salt- 

 peter, Stasfurt salts, apatites, coprolites, 

 limestones rich in phosphates, etc., as well 

 as the analysis of numerous waste products 

 and by-products, such as bones, blood, tank- 

 age, oil meals, wood ashes, etc., all of which 

 have been utilized in immense quantities, 

 the world over, for restoring worn-out soils. 



7. The control of commercial fertilizers, 

 giving the true composition and money 

 value of the brands brovight by manufac- 

 turers and dealers upon the market, in 

 order to protect the former against frauds, 

 so easily practised in articles of this nature. 



8. The composition, production, proper 

 treatment and preservation of barnyard 

 manure, the most important, most easily 

 obtainable and the best of all fertilizing 

 materials. 



9. The chemical composition of all agri- 

 cultural products, giving an insight into 

 the nature and amount of plant food re- 

 moved by them from the soil, and indica- 

 ting a proper rotation of crops, so that one 

 or the other of the essential ingredients of 

 plant food may not be too rapidly with- 

 drawn from the soil, and thus unduly 

 hasten its unproductiveness. 



These, my friends, are some of the benefi- 

 cent results which have followed the appli- 

 cation of chemistry to the production of 

 vegetable matter. In passing over to the 

 consideration of the other branch of agri- 

 cultural industry, namely, the production 

 of animal matter, it may be well to caU 



