Agricultural Chemistry. 323 



that of the manuring of the wheat field with sulphate of ammonia. 

 The sulphate of ammonia in that instance, like the phosphoric 

 acid in this, lost its influence on the crop of the succeeding year, 

 and if facts can prove an erroneous opinion, the arguments used 

 in the case of the wheat field, when employed in that of the 

 turnip field, will prove that the phosphate of lime must, like the 

 sulphate of ammonia, have evaporated through the leaves ; for in 

 no other way could it have disappeared or been lost. 



It never occurred to these observers to inquire, whether the 

 sulphuric acid, in the superphosphate, had any effect, although 

 they might have known, from the analyses of the ashes of turnips 

 by Way and Ogston, that turnips extract from the soil, and un- 

 questionably therefore require, about 50 per cent, more of sul- 

 phuric acid than of phosphoric acid. 



Two of these experiments favour the opinion that the chief 

 share, in the action of the superphosphate on turnips, belongs to 

 the sulphuric acid. 



In 1844 they manured the plot No. 13 with 400 lbs. of bone- 

 dust, 258 lbs. of sulphuric acid, and 134 lbs. of common salt ; 

 and they obtained 14 tons 10 cwt. of turnips, Avith 6 tons 11 cwt. 

 of leaves. 



In the same year they manured the equal plot No. 9 with 

 400 lbs. of bone dust and muriatic acid (= 268 lbs. of sulphuric 

 acid), and obtained 9 tons 9 cwt, of turnips, with 4 tons 6 cwt. of 

 leaves. The result of these two experiments is clear and incontro- 

 vertible. The two plots received the same quantity of phosphoric 

 acid in the same state of solubility ; both also received chlorine ; but 

 that ichich received no sulpluiric acid, yielded 5 tons of roots, and 2 

 tons 5 cwt. of leaves less than the other, which was manured, with 

 superphosphate of lime and SULI'HUIIIG ACID. 



The enormous deficiency in the crop of No. 9 cannot therefore 

 be ascribed to a want of phosphoric acid ; as little is it due to 

 the presence of chlorine ; and it is evident that the cause of the 

 difference must lie in the sulphuric acid, excluded from No. 9, 

 and that this sulphuric acid has a principal share in the effect of 

 superphosphate of lime on turnips. 



Another of their experiments is not less remarkable. In 1843 

 they manured No. 1 with 12 tons of farm-yard manure ; No, 12 

 with 2h cwt. of superphosphate of lime, 2 cwt. of rape meal, and 

 1 ton of sulphate of ammonia ; and No. 23 with 15 bushels of 

 clay and the ashes of weeds. Tlie produce was — 



tons. cwt. 11)3. 



1. No. 1 <J 9 2 



2. No. 12 11 7 3 



3. Xo. 23 11 1 3 



To appreciate justly the significance of these experiments, we 



Y 2 



