EVIDENCE OF HISTORY 259 



principles ; yet the results are available to him 

 in condensed form in the annual publications 

 of the various state experiment stations, giv- 

 ing the analyses of chemical fertilizers bought 

 in open market. These fertilizers are usually 

 designated as being especially fitted for wheat, 

 corn, potatoes or other crops, and are supposed 

 to represent the last word in scientific knowl- 

 edge as to the needs of particular crops. Thus 

 we have systematized formulas indicated for 

 the various crops, founded not on the experi- 

 ments of the manufacturers themselves, but 

 on the work of the official experiment sta- 

 tions of the many states supported by public 

 funds. 



Each manufacturer is bound, under the law, 

 to designate plainly the number of pounds 

 per hundred of the three "plant foods" his 

 mixture contains, nitrogen, potash and phos- 

 phoric acid; and if, on analysis of samples 

 bought in open market, his product is found 

 to fall below the specified standard, the man- 

 ufacturer is subject to prosecution and fine 

 and imprisonment. So well established is the 

 Liebig theory on our statute books, in fact, 

 that the "pure food" law as applied to the food 

 of plants is as definite as that applied to the 



