Farmyard Manure. 145 



many bushels of corn, which is a great hindrance to the more 

 rapid advancement of agricultural science ; and it is to be hoped, 

 for the sake of the true interests of the really practical man, that 

 the voice of those capable of understanding and appreciating 

 purely scientific results will be sufficiently powerful to keep in 

 check the too great anxiety for immediate results. 



In the next place, I beg to direct attention to the absorption by 

 the soil of the phosphates contained in drainings. If it is borne 

 in mind that the soil and subsoil with which the liquid was 

 brought into contact contained a large excess of carbonate of lime, 

 it is not more than would be naturally expected, if we should, see 

 the soluble phosphates of the original drainings converted by 

 the carbonate of lime into insoluble compounds. 



Having already remarked upon the power of this soil to retain 

 ammonia, I beg in conclusion to point out the large quantity of 

 carbonate of lime in the filtered liquid as worthy of notice. 

 This large amount of carbonate of lime is easily explained by 

 the presence of much lime in the soil. Before filtration the 

 liquid contained only about 17^ grains of carbonate of lime, and 

 after filtration as much as nearly 80 grains. Thus whilst potash 

 and ammonia are absorbed by the soil, lime is dissolved and. 

 passes into the liquid, which is filtered through the soil. Not 

 only is the quantity of carbonate of lime considerably increased 

 in the filtered drainings, but that of sulphate of lime in a minor 

 degree also. 



It is highly satisfactory to me to find the observations of Pro- 

 fessor Way with respect to the relative power of soils to retain 

 ammonia, potash, soda, and lime, confirmed in my experiments 

 with a liquid containing a number of fertilising agents required 

 by our crops. 



The composition of a liquid like the washings from dung- 

 heaps, when passed through soils, necessarily must be influenced 

 by the composition of the soils employed in the experiment. 

 The results here given and the remarks just made therefore hold 

 good only with soils of a similar composition to the one used in 

 this experiment. 



Before describing the next filtration experiments, I may state 

 that I have thought it a matter of some interest to examine what 

 amount of solid organic and inorganic matter a given quantity of 

 pure water would dissolve from the soil, the composition of 

 which has been stated above. Accordingly, one part by weight 

 of subsoil and one part of surface-soil were mixed with four 

 parts by weight of distilled Avater, and the whole, being occa- 

 sionally stirred up, left to subside for twenty-four hours, after 

 which time the water was filtered from the soil and carefully 

 analysed. 



VOL. XVIII. L 



