Tim FARMER'S MAGAZINE. 



339 



consists almost entirely of the nitrogen which wa^ 

 in combination with the oxygen consumed. It 

 serves in the air, then, to dihite the oxygen, whose 

 powerful influence would otherwise burn up all 

 animal and vegetable bodies, and, in fact, cause 

 our planet to disappear from space after a brief 

 conflagration. Therefore it is that the nitrogen of 

 the atmosphere is of such immense importance. 

 Yet it is a singular fact, and, indeed, I know of 

 none which startled chemists so much when first 

 discovered, that this apparently innoxious, weak, 

 and harmless gas is the peculiar element compos- 

 ing animal bodies, flesh, and all bodies capable of 

 supporting and nourishing flesh. They were sur- 

 prised when it was discovered that nitrogen was 

 the gas pecuhar to flesh as distinguished from fat. 

 Gluten, as distinguished from starch, was that 

 part of the food which is capable of sustaining 

 flesh and building up fabrics distinct from that 

 which is merely deposited as fat, which serves the 

 purpose of keeping the body warm, or of acting 

 as fuel in the consumption by it of the oxygen of 

 the atmosphere in the lungs, and thereby support- 

 ing animal heat. The question is, "Nitrogen, 

 what is it?" "Ammonia, what is that?" We 

 are much more familiar with the word ammonia, 

 by which we understand at once that pungent gas 

 which largely escapes from our dunghills. Its 

 strong pungent smell is chiefly due to the carbon- 

 ate of ammonia constantly escaping from it. 

 Ammonia is composed of hydrogen and nitrogen. 

 Hydrogen is the gas which forms water — nitrogen, 

 as already noticed, the gas which composes four- 

 fifths of the atmosphere. By weight, three parts 

 hydrogen and fourteen parts nitrogen form ammo- 

 nia. Thus, when an analysis is given, fourteen 

 parts of the constituent proportions of ammonia 

 consist of nitrogen : the other constituents matter 

 not; and it is the more correct when speaking of 

 that which relates to food or manure as nitrogen, 

 because, although the greater part of that which 

 escapes is in the form of ammonia, other parts 

 exist in it as a compound capable only of being 

 converted into ammonia. You are all familiar 

 with ammonia. Here is a httle in a liquid form 

 {pouring it out ) ; any gentleman who may heartily 

 sniff it {passing it round) will feel it to be strong, 

 ( La7ighler from the successive experimenters. ) 

 Here also is some chloride of ammonia ; that is, 

 ammonia fixed by hydrochloric acid, commonly 

 called muriatic acid ; in passing it round, it will be 

 found to possess none of the smell of ammonia. 

 If, however, we mix a little lime with it ( mixes ) 

 we shall presently see that this renders free the 



ammonia; and, in passing this round, you will 

 have an opportunity of testing the difference be- 

 twixt ammonia in combination and apart. We 

 possess no evidence to show that nitrogen, 

 although the ultimate and important element so 

 essential in manures and in animal bodies, can 

 be directly assimilated by plants. Otherwise it 

 would soon perform a revolution in agriculture. 

 Peruvian guano would no longer possess a mono- 

 poly, and the price of ammoniacal manures would 

 cease to be what they are at jjresent. They would 

 be no longer of value, because the atmosphere, 

 which contains no less than eighty per cent, of it 

 would give abundance of this valuable ingredient. 

 But it seems to be the design of Providence that 

 man should only earn his bread by the sweat of 

 his brow ; and that only through the means of his 

 labour and intelligence shall the fruits of the earth 

 be raised. Providence, therefore, steps in and 

 forbids the use of this important element, existing 

 so largely in the atmosphere. It is necessary that 

 nitrogen, to be of use, should assume another form, 

 and we have no evidence to induce us to suppose 

 that the nitrogen of the atmosphere can be directly 

 assimilated by plants. You are aware that carbon 

 forms the great bulk of vegetable bodies, such as 

 the root crops ; it is derived principally from the 

 atmosphere, partly from the soils, and very little 

 from manure. It is principally obtained, I say, 

 from the atmosphere ; for although it exists only 

 in the atmosphere as carbonic acid to the extent of 

 one thousandth, it is yet sufficient to build up the 

 mighty forests that cover the face of the globe. 

 Plants, by a very simple plan, imbibe the carbonic 

 acid of the atmosphere, giving off the oxygen 

 again, and converting the carbon into their own 

 structures, which are not derived from nitrogen. 

 When nitrogen becomes the food of vegetable 

 bodies, it is more common for it to unite with hy- 

 drogen and take the form of ammonia. The effect 

 of mixing two bodies without smell may then be 

 perceived. Reverting to the experiment previously 

 shown, you will perceive that the chemical effect 

 of the alkali (lime) is to unite with the hydro- 

 chloric acid, and the ammonia flies off. This 

 chloride of ammonia is more familiar to us as sal 

 ammoniac. We have seen that ammonia is one of 

 the forms in which nitrogen feeds plants ; but there 

 is another form — that of nitric acid — not the 

 strongest acid we possess, but next to sulphuric 

 acid in that respect, and better known as aqua- 

 fortis. It is a powerful caustic, and yet composed 

 exactly of the same elements as atmospheric air — 

 nitrogen and oxygen. What is more extraordinary 



