18 Experiments upon Swedes. 



A comparison of the composition of this soil with that of the 

 experimental field in 1856, shows, that the chemical characters 

 of both soils are very much alike. It will be seen that both 

 contained sulphate of lime as gypsum in appreciable quantities, 

 and I may mention, in passing, that this is the case with most 

 soils in our neighbourhood. The presence of gypsum in these 

 soils, no doubt, accounts for the fact, that gypsum is of no use 

 whatever in our neighbourhood, and I believe, generally, on 

 the calcareous soils resting on the oolite. In other districts, 

 gypsum is said to be a very useful fertilizer, especially for legu- 

 minous crops, such as beans or peas, but though I have re- 

 peatedly tried its effects on these crops as well as upon roots, 

 clover, and grass, I have never seen the slightest effect produced 

 by it. 



The proportion of phosphoric acid in this soil is appreciable ; 

 the figures stated in the above analysis express the average of two 

 separate determinations which yielded respectively : 



1st determination of phosphoric acid .. '106 per cent. 

 2nd .. -094 



Mean . . *100 per cent. 



These determinations were made with great care by a com- 

 paratively speaking new process, known to professional analysts 

 as the molybdate of ammonia process. It would be out of place 

 to describe in this Journal the precautions that have to be ob- 

 served in employing this process, but I may be allowed to ob- 

 serve, that I find no accurate results can be obtained, unless the 

 yellow precipitate obtained by adding molybdate of ammonia to 

 the acid solution of the soil, and consisting of molybdic and 

 phosphoric acid, is redissolved in dilute ammonia, and the phos- 

 phoric acid determined as phosphate of magnesia. If properly 

 executed, this process yields wonderfully accurate results, and 

 certainly is one of the most beautiful analytical processes 

 for determining, quantitatively, small proportions of phosphoric 

 acid in soils, marls, and other minerals. 



An acre of this land was measured out and divided into twenty 

 parts. The land was ridged up ; the different manures sown by 

 hand, after having been carefully mixed with three times their 

 weight of fine red ashes or burnt soil ; and the seed drilled on the 

 ridge on the 10th of June. The turnip-seed sown was that of 

 white swedes. Each experimental plot occupied four rows of 

 equal length. All the plots were sown on the same day, and 

 treated afterwards in precisely the same manner. 



The following list exhibits the arrangement of the experimental 

 field, the kinds of manures employed, and their quantities, cal- 

 culated per acre : 



