1882.] COMMERCIAL FERTILIZERS. 87 



Dr. Jenkins. As far as its agricultural value is concerned, 

 it is difficult to make a general statement. In some cases 

 the application of nitrates would do more for the crop than 

 the application of cotton seed, or dried hlood, or anything of 

 that sort; in other cases, the nitrogen of the nitrate would be 

 largely lost, and so would not be as valuable as the nitrogen 

 from the other sources of supply. In general, we say that 

 the nitrogen in nitrates is more prone to waste from the soil 

 than any other form of nitrogen, because it is readily soluble 

 in water and passes through, and there is nothing to hold it, 

 whereas the nitrogen fmm ammoniacal salts is held in a sort 

 of physical or mechanical combination in the soil and is 

 retained. I think some of Mr. Lawes' field experiments have 

 gone to show that in his case, under the conditions which 

 prevailed in those experiments, the nitrogen of rape seed was 

 as valuable, that is, produced as good results, as the ni- 

 trates. 



The Chairman. If there are no further questions on this 

 subject, the secretary will open the question box. 



Question. To what expense is a farmer to be if he wishes 

 to send samples of earth to Prof. Johnson for chemical 

 analysis ? 



Prof. Johnson. It will cost nothing but the freight. The 

 answer to that question suggests another. — " What is the use 

 of analyzing a sample of earth?" We had the idea exten- 

 sively promulgated some twenty or thirty years ago, that if a 

 sample of soil were analyzed by a competent chemist, the 

 competent chemist could tell exactly what to put upon the 

 field to make anything grow. Well, the competent chemist 

 can generally tell what to put upon the field without making 

 an analysis. Plenty of good manure will help in almost any 

 case ! 



A little calculation will readily show what a chemist cannot 

 do. You know that it has been frequently a matter of expe- 

 rience that a hundred pounds of Peruvian guano, of the old- 

 fashioned sort that we had twenty years ago, would make the 

 difference between a good crop and a poor crop, when it 

 happened to be applied to the right land, with the right crop 



