146 ON THE COMPOSITION AND USE 



I believe that this can he accomplished for many plants — as 

 for clover and all very foliaceons veg-etables, and for peas and 

 beans ; but m}^ trials are not so far advanced as to prove the 

 fact with certainty. 



Giessen University, 1845. 



Art. XXXIV.— on THE COMPOSITION AND USE OF 

 ARTIFICIAL MANURES. 



A Lecture by Professor Johnston. 



Professor Johnston said, that what he had to do, was to 

 explain the nature of what were called artificial manures, 

 and to recommend their use. In reg-ard to the nature of 

 these manures he might state to them that they might be 

 urrang-ed into two different classes — such as consisted of 

 mineral matter only, and those which were composed of or- 

 g'anic matter. He believed most of them were aware that the 

 mineral matter contained in the soil, and the mineral matter 

 contained in plants, was composed of the same substances. 

 There were a considerable number of different thing-s of a 

 mineral nature, which went to the composition of plants. 

 These were the mineral substances contained in the mineral 

 manures. Some of the manures applied to the land con- 

 day, that if the ammonia per-centage of the soil then in hand be estimated 

 as constant through a depth of 1 foot, the ammonia in an acre was about 

 8000 lb. 



Even in sand destitute of soluble mineral salts, and nearly so of organic 

 matter, he found a per-centage that was startling. Indeed, the sum of his 

 results is, that the ammonia is in nearer relation to the moisture than to 

 anything else. 



I found ammonia in the glaciers that come down from heights of 14,000 

 feet above the level of the sea — from near the summit of Mont Blanc. 

 Even at that height the ammonia is still in quantity that may be weighed. 

 Every rain and snow storm brings this ingredient to the earth. Every 

 soil that can retain its moisture will also retain the ammonia that de- 

 scended with it. Hence one cause of superiority of a soil containing much 

 decayed vegetable matter or much humus. It enables it to hold moisture, 

 as well as furnish a source of carbonic acid. A rod dipped in muriatic 

 acid, and held near the surface of a handful of moist soil, will cause white 

 fumes to rise, occasioned by a combination of the ammonia with the 

 muriatic acid. A gentle breath directed along the surface of the earth, 

 experimented with will render the fumes more apparent. E. N. H. 



