12 INTRODUCTION AS A MANURE 



general in quantities much too large. I made a number of 

 experiments in May and June, 1807, on the effects of different 

 saline substances on barley and on grass growing in the same 



garden, the soil of which was a light sand 



The solutions of the saline substances were used twice a week, in 

 the quantity of two ounces, on spots of grass and corn, suffi- 

 ciently remote from each other to prevent any interference of 

 results. The substances tried were supercarbonate, sulphate, 

 acetate, nitrate and muriate of potassa, and sulphate of soda ; 

 sulphate, nitrate, muriate and carbonate of ammonia. I 

 found that in all cases when the quantity of the salt equalled 

 -g 1 ^ part of the weight of the water the effects were injurious ; 

 but least so in the instances of the carbonate, sulphate and 

 muriate of ammonia. When the quantities of the salts were 

 i n part of the solution the effects were different. The plants 

 watered with the solutions of the sulphates grew just in the 

 same manner as similar plants watered with rainwater. 

 Those acted on by the solution of nitre, acetate and super- 

 carbonate of potassa, and muriate of ammonia, grew rather 

 better. Those treated with the solution of carbonate of 

 ammonia grew most luxuriantly of all. This last result is 

 what might be expected, for carbonate of ammonia consists of 

 carbon, hydrogen, azote and oxygen Soot doubt- 

 less owes a part of its efficacy to the ammoniacal salts it con- 

 tains. The liquor produced by the distillation of coal contains 

 carbonate and acetate of ammonia, and is said to be a very 

 good manure. In 1808, I found the growth of wheat in a 

 field at Roehampton, assisted by a very weak solution of 

 acetate of ammonia." 



This quotation gives a fair idea of the opinions held by 

 agricultural chemists as to the manurial value of ammonia in 

 the beginning of the present century. For many years no 

 further progress seems to have been made. There was in fact 

 no supply of cheap pure ammonia salts available for general 

 use. Gas liquor was too impure to be used successfully as a 

 manure ; and the sulphate of ammonia made from it by the 

 crude process of direct neutralisation and crystallisation doubt- 

 less contained sulphocyanate, and the results obtained from it 



