AMERICAN WHEAT AND CORN. 87 



the whole of the phosphoric acid, whether combined with alkalis or 

 earths as bi basic, there is still an excess of acid. The straw ashes, cal- 

 culated in the same way, show a considerable excess of base, even 

 reckoning the whole of the phosphoric acid as tribasic ; but they con- 

 tain more than 60 per cent, of silica. The question arises whether car- 

 bonic acid (if any) and some sulphuric acid and chlorine have not been 

 expelled in the incineration in the case of the grain-ashes in the pres- 

 ence of acid-phosphates, and in that of the straw ashes in the presence 

 of an excess of silica. 



9. Investigations at Eothamsted and elsewhere have established that 

 there is a general increase in the percentage of nitrogen proceeding 

 from the finer to the coarser flours obtained from the same wheat-grain, 



<and that there is marked increase in the more branny portions, the 

 greatest concentration being immediately below the pericarp. The 

 percentage of potash, lime, magnesia, and phosphoric acid also in- 

 creases from the finer to the coarser flours, and it is the highest in the 

 branny products. The percentage of potash is about ten times, of lime 

 four or five times, of magnesia fifteen to twenty times, and of phos- 

 phoric acid more than ten times as high in the dry substance of the 

 bran as in that of the finer flour. It is also established that, in com- 

 parable cases, the better matured grains contain the lower percentages 

 of nitrogen and total mineral matter, and a higher percentage of stare ij 

 .and the ash analyses now under consideration consistently show a lower 

 proportion of the chief individual mineral constituents in the grains of 

 better quality. 



10. The average annual amounts of total mineral cons tituents in the 

 crops per acre (grain and straw) over the sixteen years were with 

 farm-yard manure 237.4 pounds, without manure 106.1 pounds, and with 

 ammonium-salts alone 142 pounds ; that is, with ammonium-salts one 

 and a third times, and with farm-yard manure more than twice as much 

 as without manure. With ammonium-salts the greatest proportional 

 increase was in lime, potash, magnesia, soda, sulphuric acid, and chlorine, 

 and the least in phosphoric acid. With farm-yard manure, by far the 

 greatest increase was in potash, of which there is more than two and 

 a half times as much as without manure; and there is about twice as 

 much magnesia, and more than twice as much lime, phosphoric acid, 

 sulphuric acid, soda, and silica, and nearly four times as much chlorine. 



11. Comparing the amounts of the individual ash constituents in the 

 wops per acre over the first eight years with those over the second eight? 

 they are, without manure, in the grain nearly identical, but in the straw 

 there is more or less deficiency of every constituent, excepting lime, over 

 the second period. Deficiency in the straw and total produce, generally 

 but not uniformly, indicates deficient source. With farm -yard manure 

 there was more of every ash-constituent (excepting sulphuric acid) in 

 the grain, straw, and total produce, over the second period; the most 

 marked increase being, in the grain in potash and phosphoric acid, and 



