KNOWLEDGE 



[Oci 



, 1885. 



if the smaller r.iilways into their respective sy.-stems, 

 represent £644,246,350 of the total capital of the various 

 lines open, leaving- £78,718,559 as the capital of the 

 icmaining lesser lines. The fifteen leading lines, 

 us above named, have an aggregate length of 

 13,475 miles, an analysis showing that, as respects 

 mileage, the Great Western Company stands at the 

 liead, while the London and North-Western Company 

 has the largest amount of capital, being £101,771,907, 

 with a mileage 1,794 miles in length. As re- 

 gards capital, the Midland Company is next in 

 limount, with £76,549,267, and 1,270 miles of rail- 

 way. The capital of the Great Western Company is 

 £75,108,424, and its length of railway 2,301 miles. 

 Then follow the North - Eastern, with a capital of 

 £57,650,895, and 1,536 miles of railway; the Great 

 Eastern, capital £41,087,103, and 919 miles of rail- 

 way; the Caledonian, capital £36,324,700, and 772 

 miles ; the Great Northern, capital £35,380,050, and 949 

 miles ; Lancashire and Yorkshire, capital £41,852,949, 

 and 496 miles ; North British, capital £33,576,211, and 

 984 miles ; Manchester, Sheffield, and Lincolnshire, 

 capital £27,248,627, and 291 miles; London, Chatham, 

 and Dover, capital £25,634,008, and 176 miles ; London 

 and Brighton, capital £23,768,899, and 455 miles ; Sonth- 

 Bastern, capital £21,915,824, and 385 miles ; London and 

 South- Western, capital £29,455,931, and 818 miles ; and 

 Glasgow and South-Western, capital £13,921,570, and 

 330 miles.— 27ie Times. 



NITRIFICATION. 



By E. W. Prevost, Ph.D. 



THERE are several questions which are frequently 

 asked by an inquiring person possessing scientific 

 proclivities ; whenever he sees or hears of natural phe- 

 nomena which have not been explained to him, but 

 which he thinks are capable of explanation, he launches 

 out with "How does that happen r " "What makes it 

 do that? " But siich questions as these are most generally 

 asked of phenomena occurring above ground, or if fi.sked 

 of anything taking place below ground, it is usually in 

 connection with something more or less visible ; as, for 

 example, the inquirer is aware that after a grain of 

 wheat is sown, it will sprout and grow; his ques- 

 tions are therefore directed to the cause of its 15| rout- 

 ing, and the food of the future plant, <fec. But 

 concerning that which to the general observer is in- 

 visible there is but little curiosity evinced, and it is to 

 one of these invisible phenomena that I now wish to 

 direct the reader's attention, for although the phe- 

 nomena referred to has been known for many years past, 

 yet it is only quite recently that the true explanation 

 has been forthcoming. 



I have in previous articles referred to those consti- 

 tuents of the soil on which the plant, when growing, 

 feeds ; and I also showed that all the food derived from 

 the soil must be in a state of solution. My object now 

 is to direct special attention to the very important food, 

 nitrogen, which exists in at least two forms of combina- 

 tion, both of which are soluble in water, but one is of use 

 to and is absorbed by the plants, wliilst the other must 

 be converted into the first, utlidwiM' it i,-, of no use. 

 For the first form nitrogen is eiuiibiiird wuh oxygen, and 

 exists as nitric acid combined with lime (calcium nitrate), 

 and in general it is spoken of as the "nitric acid" in 

 the .soil ; the second appenrs as a compound of amnr.onia, 



111. - • ■ I . ,.il,e .supply 



.ry :: |! . , ■ iIm.iv is also 



ilriiri. u•'^. :h,.| i!,:it is to be 

 y c.f the .salt itself, and the in- 

 let ain nitrates, as it does most 

 iiseqnence of all this is, that 



where llie iiitroneu i^ eoinliined with hydrogen, and it is, 

 Irepe::t, iiilliis f.imi th;it nitrogen is not acceptable to 



large quantity of " niti-ie neiJ " ('n ii riii ,-') .xisls in any 

 soil, because the demu 

 being barely sufficient 

 a further reason for 

 found in the very miIi 

 capability of the eurLl 

 other compoumls ; tli _ 



much of the must valuable material is to be found con- 

 stantly, and at all times of the year, but mere especially 

 during wet, wintry weather, in the drainage waters. 

 Whence, then, comes this nitric acid, which, if there were 

 not an unfailing and continuous source, would so soon 

 be absent from our soils 1 The knowledge that com- 

 poimds of ammonia may be converted into nitric acid — 

 that, under certain conditions, oxygen may replace hy- 

 drogen — is not of very recent date, but the cause of this 

 conversion in the soil has been ascertained only during 

 the last few years. 



It was not until 1877 that Sehldsinfr and Miintz showed 

 that this process of eunvei-si..ii. m.w called nitrification, 

 was due to an organised f(.niii ui , mid our more extended 

 information is very lui't^ely ihu- t^ Mr. Warington, at 

 Rothamsted. It would occupy a far greater space than 

 the editor can spare to describe fully all the results which 

 Mr. Warington has obtained, so that it must suffice to 

 state in as few words as possible the chief points. That 

 the ferment shall grow it is necessary that nitrogen in some 

 form other than that of nitrates be present. The process 

 is slow at 0° C. (32° F.), increases as the temperature 

 ri.ses up to 35° C. (91° F.), at which point the action is at 

 its maximum, after which it decreases until 55° C. 

 (l.'-.r F.) is reached, when it ceases altogether. Like all 

 other ferments, antiseptics are fatal to its action. The 

 nitrogen in sewage or soil heated to the boiling-point of 

 water will no longer be converted into nitric acid as the 

 ferment is killed, but if some fresh soil be introduced 

 into the sterilised liquid, then nitrification recommences. 

 Knowing now these the chief points in the discovery, let 

 us sec what effect the conditions under which nitrifica- 

 tion proceeds has upon the soil in a field. Taking it, 

 therefore, that we have abundant proof that it is to the 

 nitrogenous compounds in the soil that we have to look 

 for thi' supply of nitrates, are we to believe that nitrifica- 

 tion proceeds aetivelv all tlie year round, when in winter 

 the Jilauts liardlv 'jn.w and require but very little 

 nitrnireii, and \v1m".u -reat Ic.s wnuld oeeur through the 

 :luable 



; fi.r 



. fur 



1 the 



ground is frozen there is no formation of nitric acid; in 

 the lower stratum of soil, when the temperature has not 

 fallen below 0° C, there is, of course, some nitric acid 

 being produced. Part of this may be absorbed by roots 

 of the crop in the land, whilst the rest will most probably 

 be lost. 



Being acquainted as we arc, and as I have pointed out 

 in a previous article, with tlie valuable changes taking 

 place in the soil during winter and svimmer, we are now 

 more able to appreciate one of the disadvantages of per- 

 mitting a field to lie fallow— j'.e., to carry no crop during 

 winter and summer. I do not wish to argue that fields 

 should not lie fallow, for there are very many benefits 

 derived from such a state of affairs, but I am anxious to 

 point out clearly that there is a loss incurred. In the 

 summer the temperature is high, and consequent active 

 nitrification takes place ; but as there is no crop to take 



