THE GARDENERS 



CHRONICLE 



• F^tT^ToTfoh^^ who can 



LT a Potato. And with this character, and the 

 following extract from Loudon, we dismiss it. 



« The leaves are used as Spinach, and sometimes 

 W . >.* t.nder stalks. The stalks are good only 

 while the plant is young ; but the lar ger leav es may 



and no accurate physiological or chemical experi- 

 ment has been adduced to bear out the supposition 

 that plants ever directly absorb nitrogen from the 

 • On the other hand, there are thousands of facts 



constaiA 



\ atmosphere 



i 



be picked off in succession throughout the season 

 le^ing the stalks and smaller leaves -^-he > ^ 



^4*ich proTe V that\7tir a mmonia and nitric acid are j earthy by dew and rains." It has been que S [ io J 

 eagerly absorbed by plants ; they grow with remark- whether that portion of rain-water which »2 



able vigour, and, on subsequent analysis such plants 



are found richer in nitrogen than other plants not so 



. rUo Qnino^h I fpd The simple and evident conclusion to which 



whichthe latter w^ i = e ,„ . j^Jfc^ {& JE {T£a, ta. « 1W » is not proved 

 ,ha S »««■"* »3 e ^ d S5r Cm seeds, which [that plants are wholly unable to _absorb,any of the 



in drills 2 feet 



France, 



may be sown early in spring 



their roots, could contain ammonia enough to mi 

 them with the requisite quantity of nitrogen Jr 

 has been supposed that a heavy rain must of nJ 

 sity soak far into the soil, and consequently^ 



free nitrogen of the air, yet, that under all ordinary away, and remove altogether beyond the reach c 



3 ay be ^» ^ 2 'IteSI thinned out till circumstances, they mnst derive their nitrogen from 

 part, the plants being a fterwar ^^^ ^ ^ ^ ^ . source belng most probably 





they are 2 feet distant in the rows 

 in/made about the middle of June will ensure a 

 succession of leaves ; but the size and succulency of 

 these will of course depend a good deal on the nch- 

 mess and moisture of the soil. (Gard. Mag vol n., 

 p 178 ) To save Seed.— Leave a few plants of the 

 most tender and succulent constitutions to blossom, 

 and they will produce abundance of seeds in 



August." 



We published, at the close of last year, a brief 



account" of some experiments now in progress, on 

 the absorption of nitrogen by plants from the air ; 

 and on the influence of ammonia on vegetation, by 

 M. Ville, which are described in the Comptes Rendus. 

 As this is not merely a subject of scientific interest, 

 but also one of great practical importance, we shall 

 again draw attention to M. Ville's experiments, and 

 briefly state some of the points which bear upon the 



effect in question. 



Thirty years ago, the importance of nitrogen as 

 an element of plants, was scarcely known or acknow- 

 ledged by any one. Davy, and the chemists who 

 preceded him, spoke of it almost in the light of an 

 accidental impurity ; and it is only within the last 

 20 years that we have heard much about the im- 

 portance of this substance to plants. Investigations 

 into the nourishment of animals very naturally led 

 to the recognition of nitrogen as an important ele- 

 ment of plants, because, as that peculiar gas was 

 found to be a component of most animal substances, 

 and to exist, in considerable quantity, in the flesh 

 and blood of all animals, physiologists soon began 



ammonia and nitric acid. § 



Lengthened and ingenious calculations have been 

 made to ascertain, whether it is possible that plants 

 could obtain from the air and soil a sufficient quan- 

 tity of ammonia and nitric acid, to supply them with 

 all the nitrogen which they require ; but these cal- 

 culations are all more or less founded upon mere 

 assumption. The fact is, that though it has been 

 known for a considerable time, that the air fre- 



quently contains a small quantity of ammonia, yet direct bearing upon the use and action of ma* 

 Ljucutij *, _ ^ .,_ x , 1 / 1 ui^t^n;*. it is pretty well ascertained that the two:, 



■ 



ma thus brought down irom tne air ; that this latfe 

 however, is not the case, has been satisfactcr 

 proved by recent experiments, to which we $ ; 

 shortly draw attention. Such a calculation is nee* 

 sarily vague and incomplete ; but as far as can 

 judged, it appears most probable that plants area!. 

 to absorb enough nitrogen from the air and soil | 

 supply all their wants, in the forms of nitric acid* 

 ammonia. 



It is obvious that this inquiry has a Tery import 



in consequence of its great volatility, and the facility 

 with which it is absorbed by water, and still more 

 in consequence of the very minute quantity of it 

 which can at any time exist in a given bulk of air, 

 its detection and estimation by chemical means is 

 exceedingly difficult, not to say almost impossible. 



valuable ingredients of dung, and similar r> 

 manures, are the phosphoric acid and nitrogen *fe. 

 they contain ; and it is plain that the quantity 

 the former which plants are able to take up z. 

 depend upon the proportion of it naturally exist: 

 in the soil, or artificially added to it. In the a 



In many inquiries of this sort, facts may be satisfac- 



torily established by induction, and we may feel of ammonia, however, it must be ^ different n 



tolerably well convinced of their truth, without quantity which plants contain is independent of 4 



being able to settle the question beyond all dispute soil altogether, and depends -j>n the proporta 



$ - ••* ■»* •- -- There is which they are able to collect from that unhnuts 



to look at plants, as the probable source of this sub- 

 stance, and arrived at the conclusion that vegetable 



In fact, 



food must be chiefly valuable, in proportion to the 



quantity of nitrogen which it contained. 



there were only two sources whence herbivorous 



animals could well be supposed to derive nitrogen, 



and these were, the atmosphere and their vegetable 



food. Experiment soon showed that such animals 



could not, by any arrangement, be made to thrive 



on food containing no nitrogen, even though they 



were supplied with plenty of fresh air; that, in 



fact, they could not thrive unless they were fed with 



vegetable matter containing nitrogen. A few years 



since, this conclusion was still further confirmed, 



when it was ascertained by direct chemical analysis, 



that the substances which exist in the blood of 



animals, and which are necessary to their growth 



and to the development of muscle, really and truly 



exist ready formed in those plants which constitute 



the food of animals. 



The true source of the nitrogen which exists in 

 animals, was, however, only half made out ; it was 

 satisfactorily established that though they might, 

 and very possibly did. derive some small portion of 

 it directly from the air, yet that the greater part 

 must be obtained from plants. The next question 

 of course was, whence then do plants derive it? 

 This enquiry is still undecided, though certainly 

 there is a great mass of evidence, all tending to 

 show that like animals they do not absorb nitrogen 

 in the free state, but only in a state of combination, 

 and as a compound already formed by some other 



agency 



and animals, h 



owever, 



there would seem to be this important distinction, 

 that whilst the latter absorb nitrogen in the form of 

 an organic combination, that is to say as vegetable 

 matter, plants absorb it in the form of an inorganic 

 compound ; it being their especial office to combine 

 it with other substances, and so form or elaborate 

 organic matter fit for the nourishment of animals. 



The great majority of facts tend to show that 

 plants, though they grow in the free and open air, 

 surrounded therefore with plenty of uncombined 



nitrogen, absorb little or none of it; but that they 

 require to have it previously combined by some 

 chemical process with another element, either oxygen 

 or hydrogen. The experience of practical men as to 

 the growth of plants, and the influence of soil and 

 climate on their development, and more especially 

 the action of manures, all lead to the conclusion that 

 ammonia and nitric acid, even in minute quantities*, 

 exert a very remarkable influence on vegetation, 

 which is healthy and luxurious when they are 

 present, and comparatively sickly and weak if they 

 mxa ftltftaoihov ovMnripr] N known practical fact, 



by direct and unexceptionable evidence, 

 no doubt whatever that there frequently exists in 

 the atmosphere a very considerable quantity of 

 various foreign matters, which though they are too 

 subtle to be detected by the use of chemical tests, 

 may nevertheless be sometimes shown to be present, 

 and which produce various important effects on the 

 health of animals, and also in other ways. It would 

 be well if the attention of chemists were drawn 

 to this very curious and interesting subject, for there 

 can be no doubt that improved modes of detecting 

 the presence of foreign matters in our air would lead 

 to the most important practical results in a sanitory 

 point of view. The power which steam and vapour 

 generally possesses, of assisting in the evaporation 

 of less volatile substances has been long known, but 

 very little is known of the extent to which this 

 influence extends in nature, or the effects to which 

 it may give rise. Recent experiments have shown 

 that steam is able to carry away, in a state approach- 

 ing nearly to the form of vapour, the most fixed 

 substances, such as soda, oxide of iron, &c. ; and 

 there are others which render it probable that steam 

 is also sometimes able to cause the volatilization of 

 some forms of organic matter. If this should prove 

 to be really the case, it w ? ill lead to very interesting 

 inquiries respecting the spread of disease in the air, 

 and the nature of contagion. 



Although, however, we have difficulty in obtain- 

 ing direct evidence of the existence of either ammo- 

 nia or nitric acid in the atmosphere, yet we are sure 

 it must frequently exist in the air, because we know 

 that all organic matter, when in a state of putrefaction, 

 evolves ammoniacal gas. It is also evolved constantly 

 by the bodies of all living animals, constituting an 

 ingredient of their perspiration ; and it is also con- 

 tinually being formed and poured into the atmosphere 

 by the combustion of coal. Again, in the formation of 

 nitre in soils, we have further evidence of the pre- 

 sence of ammonia. When a soil contains potash or 

 some similar base in contact with putrefying animal 

 matters, nitric acid is formed, but in such cases the 

 nitrogen appears to pass through the intermediate 

 state of ammonia ; that is to say, that the putrid 

 matters do not at once generate nitric acid, but that 

 they form ammonia, which, in the presence of pot- 

 ash, &c, is in turn converted into nitric acid. In 

 soils which have been manured it is easy to trace the 

 origin of nitric acid, but in those soils which have 

 never been artificially manured in any way, but which 

 continue from time to time to yield fresh crops of 

 nitre by mere exposure to the air, there appears 

 little doubt that the nitric acid thus formed is pro- 

 duced by the action of potash naturally existing in 

 the soil, on ammoniacal vapours which are brought 

 from a distance in the air. 



source, the atmosphere. It is evident tk 

 plants are able to appropriate the nitrogen of 4 

 air, our views, respecting the application of mar 

 must be considerably modified j because the quest 

 will no longer be, how to fix ammonia, and hoi 

 supply plants with a certain quantity of nitroga: 

 a state of combination, but rather how to I 

 plants into that state in which they are best at 

 appropriate the nitrogen of the air. 



Always, therefore, bearing in mind, that it 

 no means impossible that plants may absorb aj 

 tion of free nitrogen, we must say that prota 

 is much against it. At the same time the up 

 is one of great interest, and well worthy of i 

 careful investigation, but the experiments mn 

 devised with judgment, and carried on wit: 

 most scrupulous care, and unwearied attention 

 the difficulties which surround such mvestigj 

 are very numerous, and without constant* 

 some of them would be sure to escape the i obsj 

 notice. In all experiments on the growth oiP 

 under glass cases, and in confined portions < 

 there are more or less unnatural conditio*- 

 troduced, which render it very difficult tarn; 

 compare the results obtained, with those * 

 observed when plants grow under natural cp 

 stances, or in the free and open air. In mostfj 

 we observe a superabundance of means ;. ow 

 provided more powerful or more abundan t u* 

 absolutely necessary to carry on the h&m 

 tions of the plant ; instead of merely lormj 

 seeds, a plant produces hundreds or thousanu , 

 in a great many cases much more orgamc 

 is laid up for the use of each seea^ 

 under any ordinary circumstances w 

 can possibly require. Some seeds j 



abundant a store of food, that even 

 of it is destroyed accidentally, or puij^. 

 moved, the remainder is sufficient to no 

 embryo, and ensure the growth of a pe 





- - 8 ,^ vn ; * fruit trees 



Others again, such as the seeds oi irw 



not merely thus amply provided with o g 

 but in addition they are furnished WM» 

 quantity of manure ; for the fleshy cover , 

 constitutes the edible part of the g^^fl 

 in the soil, or on the ground when the i ir . 

 rots, forms a quantity of rich mould ior 



plant, when the seed subse- 

 The beneficial consequences * 



the young plant, when the seed suDseu 



- ' ^sequences w«g 



from these curious and beautiful P r ? 



minates. 



altogether excluded. 



The quantity of nitric acid formed in the soil in 

 many places, particularly in the vicinity of towns, is 

 probably even much larger than is generally sup- 

 posed. The earth below the pavement of towns, 

 and that surrounding drains even to a very consider- 

 able distance, frequently contains traces of nitric 

 acid in combination with lime and potash ; and 

 even the water of the surface springs, such as tho.se 

 which generally supply street pumps, are in many 

 cases found to contain small quantities of these salts. 

 There appears, in truth, to be no doubt whatever 



Li til 



evident throughout the whole ve S et yP the 

 Amongst other effects thus producea j 

 which plants have of withstanding ^^ 

 various external agencies,and other acci ._ -r- 



which would inevitably destroy 



for their great vitality, and the rem 



arkable 



them if « f!. 



which they have of adapting themsei 

 rounding circumstances. 



vitality of plants 

 exceeds that of animals, and the CA ^ xtf <$& 



This great 



which tf 



in which plants live and continue to gro > c , 

 under the most disadvantageous mic u > r - 

 in the most unnatural situations, is, n ^d 

 unfavourable, in some respects, to ^jg# 

 the nutrition of plants. When an aniu» 

 to a certain point, it will then gree<wy 



