INTRODUCTION AS A MANURE 13 



were uncertain. The quotation given in the preceding section 

 from Fownes' Prize Essay, written in 1842, shows in a strik- 

 ing manner how little was at that time certainly known 

 respecting the manurial value of ammonia salts. Nor was it 

 only the chemist who hesitated in pronouncing an opinion 

 upon the subject. Philip Pusey, perhaps the most advanced 

 agriculturist of his day, in his paper " On the Progress of 

 Agricultural Knowledge during the last Four Years" (Jour. 

 Roy. Agri. Soc. 1842, 169), tells us that he has, for the first 

 time, tried on several fields of wheat " the sulphate of ammonia 

 extracted from gas- water. It acted precisely as the nitrate of 

 soda, darkening the colour of the plant, and lengthening the 

 straw and the ear even more than the nitrate, but it certainly 

 did not pay. Again we have the principle, and we must learn 

 to combine it." 



Numerous carefully made field experiments were, however, 

 soon to throw light on the conditions necessary for the success- 

 ful use of sulphate of ammonia. At the close of 1842, Mr. \Y. 

 M. F. Chatterley described to the Chemical Society (Chem. 

 Soc. Memoirs i, 152) his very successful trials of sulphate of 

 ammonia as a manure for wheat, oats, and pasture. After 

 describing his results, he says : 



" From the above experiments, and several others . . I 

 am led to believe that no cheaper top-dressing than sulphate 

 of ammonia can be applied to wheat or oats on this land, 

 which is generally a heavy clay upon a subsoil of London clay, 

 when the plant requires it, either from its being sickly or thin 

 on the ground, in consequence of the land being somewhat out 

 of condition, whether from unusual wet, bad seed-time, uncon- 

 genial spring, or any such-like cause. I should add that equal 

 benefit appears to have been derived from its use upon a light 

 gravelly soil upon a subsoil of gravel, upon the same as the 

 London clay formation. . . . The price paid (for the sul- 

 phate of ammonia) was seventeen shillings per cwt. ; it is 

 prepared at the Gas Works in Brick Lane by a patent 

 process for purifying coal-gas by means of dilute sulphuric 

 acid, and is very free from impurity." 



In 1843, the systematic trial of ammonia salts, and other 



