666 ANNUAL REPORT OF THE Off. Doc. 



forces governing the chemical changes of the mineral kingdom; and 

 it was not until well on in the second quarter of this century, that 

 the brilliant discoveries of Woehler, Berthellot and others had proven 

 that from purely inorganic materials the formation of substances 

 heretofore regarded as distinctly products of vital action, could be 

 made by purely laboratory methods. The resulting change in the 

 conception of the active forces governing the production of plant 

 and animal materials may oot have been essential to the final at- 

 tainment of the facts now at our command, but did much to make 

 investigations along these lines promising of fruitful result, and 

 to this stimulus much of our present knowledge is doubtless due. 



Possibly a better idea of the condition of knowledge upon the 

 subject of agricultural chemistry may be had if we recall that at the 

 beginning of the eighteenth century, scarcely fifty years had elapsed 

 since the alchemist was spending most of his efforts in the at- 

 tempt to discover the 'philosopher's stone' by which the transmuta- 

 tion of common substances into gold might be accomplished, or to 

 the discovery of the 'elixir of life' whereby the ravages of age and dis- 

 ease might infallibly be overcome. While it is true that the Arabian 

 physicians of the middle ages had separated quite a number of our 

 common chemical principles, such as alcohol and caoe sugar, the 

 systematic methods of chemical research were exceedingly crude; 

 the method of distillation by comparatively high heat was almost 

 the only means used for the separation of chemical substances of 

 organic origin during the first quarter of the eighteenth century. 

 Better results attended the later application of mild solvents for the 

 purpose of separating organic materials. The discovery of the 

 chemical nature of gases and the perfecting of the chemical balance, 

 so that quantitative analysis became possible, did not occur until 

 the last half of the eighteenth century. It need, therefore, be mat- 

 ter for little surprise that the chemical and mineral differences be- 

 tween soils and their components was not fully understood one hun- 

 dred years ago and thr-t the information possessed concerning the 

 readily decomposable constituents of plants and animals was of the 

 crudest description. From this state of great ignorance, through 

 a spirit of active and patient investigation, we have made considera- 

 ble strides toward the attainment of the knowledge necessary to 

 the complete mastery of our business. 



Let us glance briefly at some of the fundamental achievements 

 of our time and also strive to discern as well the lim- 

 itations and failures in our work. By the application of new 

 and refined methods, hundreds of substances, heretofore un- 

 known, have been separated from plants and animals. The 

 chemical constitution of most of them has been determined with 

 more or less accuracy and, in many instances, the relation which 



