SCIENTIFIC FARMING AT ROTHAMSTED. 85 



Weio-hed portions of each are partially dried, and preserved for future 

 reference or analysis. Duplicate weighed portions of each are dried 

 at 100 C, the dry matter determined, then^ burned to ash on plati- 

 num sheets in cast-iron muffles. The quantities of ash are determined 

 and recorded, and the ashes themselves are preserved for reference or 

 analysis. In a large proportion of the samples the nitrogen is deter- 

 mined, and in some the amount existing as albuminoids, amides, and 

 nitric acid. 



" In selected cases illustrating the influence of season, manures, 

 exhaustion, etc. complete ash-analyses have been made, numbering 

 in all more than seven hundred. Also in selected cases, illustrating 

 the influence of season and manuring, quantities of the experimentally 

 grown wheat-grain have been sent to the mill, and the proportion and 

 composition of the different mill-products determined. 



" In the sugar-beet, mangold-wurzel, and potatoes, the sugar in the 

 juice has in most cases been determined by the polariscope, and fre- 

 quently by copper also. 



" In the case of the experiments on the mixed herbage of permanent 

 grass-land, besides the samples taken for the determination of the 

 chemical composition (dry matter, ash, nitrogen, woody fiber, fatty 

 matter, and composition of ash), carefully averaged samples have fre- 

 quently been taken for the determination of the botanical composition. 

 In this way, on four occasions, at intervals of five years viz., in 1862, 

 1867, 1872, and 1877 a sample of the produce of each plot was taken 

 and submitted to careful botanical separation, and the percentage, by 

 weight, of each species in the mixed herbage determined. Partial 

 separations, in the case of samples from selected plots (frequently of 

 both first and second crops), have also been made in other years." 



This condensed statement of the plan of the field experiments, and 

 brief outline of some of the work performed in connection with them, 

 from the " Memoranda " for June, 1882, will give some general idea 

 of the extent of the Rothamsted Station, and of the thorough manner 

 in which all operations are conducted ; but, in our enumeration of the 

 other lines of inquiry now in progress, we can only mention the sub- 

 jects of investigation without referring to particulars in the methods 

 practiced, as we wish to save space for a discussion of some of the 

 leading results that have been thus far obtained. 



More than one thousand samples of soil have been taken from the 

 experiment-plots, at different depths, for the purpose of analysis, to 

 ascertain the rate of soil-exhaustion under different conditions, and to 

 trace the relations of the soil to the crops grown and to the manures 

 applied. 



For nearly thirty years the rain-fall has been measured in a gauge 

 having an area of one thousandth of an acre, and frequent analyses 

 have been made to determine the available supply of combined nitro- 

 gen in the form of ammonia and nitric acid that can be obtained by 



