214 PROCEEDINGS OF THE CHEMICAL DEPARTMENT. 



last year tended to the conclusion that in this respect there is no 

 difference between ready formed ammonia and glue, when applied 

 to the turnip. They went even further, for it appears that when 

 used alone they are absolutely without effect on that crop, except 

 when used on a soil in very high condition — that is to say, charged 

 with the elements of manure — in which case a slight effect is 

 manifest ; that they slightly increase the yield when soluble 

 phosphates are associated with them; but in no case is the effect 

 obtained at all proportionate to the amount of nitrogen used ; 

 neither can it be said that the ready formed ammonia on the 

 whole surpasses the unformed, but on this point the results of a 

 single season are not sufficient to justify a decided expression of 

 opinion. 



The experiments of the season 1866 were further directed to a 

 question much discussed among practical men, namely, whether 

 soluble phosphates derived from mineral sources, such as coprolites, 

 apatite, and the like, are or are not manurially inferior to those 

 which, for convenience' sake, may be said to be of organic origin, 

 such as those contained in guanos and bones. So far as insoluble 

 phosphates are concerned, there can, I apprehend, be no difference 

 of opinion, for the hard and compact phosphates of mineral origin 

 are much less accessible than the soft and highly divided sub- 

 stances found in guano ; but it is different when they are converted 

 into superphosphates, when the manufacturer, by means of the 

 acid he uses, converts them all into the same compound, and 

 annihilates all the differences which previously existed between 

 them. I have, on this ground, maintained that there ought to be 

 no difference in soluble phosphates, from whatever source obtained ; 

 but as experiment is necessarily always most convincing, the 

 solution of this question was also made a part of the investigation 

 of 1866. 



It had been resolved from the very first by the Field Experi- 

 ment Committee, that any inquiries undertaken by the Society 

 should be continued on the same plan for several years, so as to 

 eliminate the effect of weather and other disturbing causes. This 

 resolution, however, did not exclude the introduction of such 

 modifications and improvements as the experience of successive 

 years might induce them to adopt, and accordingly, in arranging 

 the experiments for 1867, two very important questions came up 

 for consideration. 



The first of these related to the scale on which the experiments 

 should in future be conducted, on which point much difference 

 of opinion prevailed. It was maintained by some of the Com- 

 mittee, that the results obtained on plots of so small a size as 

 T l^th of an acre could not be relied upon for indicating what 

 would be obtained on the large scale ; others, and among them 

 must be reckoned the greater number of those who had had 



