314 Agricultural Chemistry. 



most efScacious manure. According to cm- present knowledge of the con- 

 stituent (efficacious) parts of manure, I feel convinced that it is indifferent to 

 the plants from which source they are derived. The dissolved apatite of 

 Spain, the i^otash from feldspar, the ammonia from the cjas-works, must 

 exercise the same effect on vegetable life as the bone-earth, the potash, the 

 ammonia, which we provide in (ordinary) manure.'' * 



" We live in a time when this conclusion is to be subjected to a comjn-e- 

 hensive and accurate trial, and if the result correspond with the expectations 

 we are entitled to form, if animal excreta can be replaced by these efficacious 

 elements, a new era of agriculture must begin." — p. 19. 



At the desire of some friends I resolved, in 1845, to make the 

 attempt to assist in realising these views. I communicated to 

 them a series of prescriptions for the preparation of artificial 

 manures for different crops, in which all orf^anic constituents 

 were excluded. The nitrogen required to increase the produce 

 was to be added to them in the form of ammoniacal salts. In 

 my paper on Artificial Manures I said — 



" Salts of Ammonia. — It may be regarded as certain, that the nitrogen of 

 plants is derived either from the ammonia of the atmosphere, or from the 

 manure which is provided in the shape of animal excreta, fluid and solid ; and 

 that nitrogenous compounds exercise an effect on the growth of plants only 

 in so far as they give up their nitrogen in the form of ammonia during their 

 decomposition and decay. We may, therefore, profitahly replace all nitrogenous 

 compounds by compjounds of ammonia.'''' — p. 26, 



Again, 



" All manure tuhich is to be used next tuinter, contains a quantity of am- 

 monia corresponding luith the amount of nitrogen in the grain and crojjs 

 which are to be grown. Experiments, in which I am at present engaged, will 

 show whether in futiire the cost of this manure may not be greatly lessened 

 by excluding the half or the whole amount of ammonia. I believe that this 

 can be accomplished for many plants, as for clover and all very foliaceous 

 plants, and for peas and beans ; but my trials are not so far advanced as to 

 prove the fact with certainty." — Address, p. 21. 



The passages just quoted contain the most indisputable proof 

 that the mineral manure, prepared according to my pi'escriptions, 

 was to contain the constituents of the ashes of the plants to be 

 cultivated, loitli a certain quantity of nitrogen,, in the form of am- 

 moniacal salts corresponding to the composition of the crops, and 

 the amount of nitrogen req^dred by them. And the proof that 

 these manures contained ammonia as a constituent is found in 

 the testimony of Mr. Lawes, which establishes the actual pre- 

 sence of ammonia in them. He says (Journal, vol. viii. p. 245), 

 that he distinctly recognized ammonia by its smell. 



The object in view was a complete revolution in agriculture. 



Farmyard-manure was to be totally excluded, and all the 

 mineral constituents removed in the crops were to be restored in 

 the mineral manure. The usual rotations were to cease. 



* Verbally, from the German original, which is printed in the second edition 

 of A. Tetzhold's ' Lectures on Agricultural Chemistry.' 



