THE FARMERS' REGISTER. 



61 



in our (arm-yard manures, and ihou^li writers j 

 diHer in opinion as to ihe amount oriiiHuoncc ac- 

 tually ami coiisianily exercised hy iliis compouiul 

 on ilie general vegetation of the globe* they all 

 agree in altribuiinj^ lo il a very bf-iielici.il aciiou 

 on growins plants in general, when a[iplied to 

 them in a'sufficien'ly diluted state. In propor- 

 tion, ilien, to the quantity ol' ammonia it coniains 

 will the value ol the guano t)e im-reased, and 

 hence one reason why the more recent varieiies 

 ehould he accounted the hest, and should bring 

 the hijzhe&t price in liie market. 



2. Next to ihe ammonia, or perhaps equal to 

 it in value, though in the t pecimens I examined 

 very much less in quantity, ts the, uric acid. 'I'his 

 substance, as il dtcompo^-es, izives rise among 

 other products to tiie formation and evolution oi 

 ammonia in consideralile quantity. Under the 

 most I'avorable conditions 100 of pure uiic i'.cid 

 might yield 40 oT pure ammonia. In nature, 

 Jiowever, these conditions probably never occur, 

 60 that during its decomposition, numerous other 

 products containing nilrojien are lormed (prue-ic 

 acid among the rest,) wiiich it is unnecessary 

 here to specify. We know little liiat is certain 

 in regard to the action of these products on the 

 growth of plants, but the well known eHect of 

 liquid manure, which in a state of li?rmenialion 

 contains the most of them, leads to the beliel that 

 they are filled to promote vegetation. 



The fresh guano is more valuable, chiefly be- 

 cause it contains more of this uric acid in an un- 

 decomposed stale. We have no analyses of the 

 recent droppings of any of the birds which fre- 

 quent the shores of Peru ; they would probably 

 be found to difier in some degree, not only wiili 

 the species of bird, but also with the kind of 

 fishes on which at different seasons of the year 

 they were lound to prey. We possess analyses, 

 however, of the excretions of other birds which 

 hve chiefly upon fish, from which we are enabled 

 to form an opinion as to what the recent guano is 

 likely to be. Thus Dr. Wollaston found Ihose of 

 the gannet, (Pelicanus bassanus,) when dry, to 

 contain little else but uric acid, while in those o( 

 the Bea-eagle, Coindet found — 



Solid Excretions. 



Ammonia - 92 



Uric acid 84 65 



Phosphate of lime 613 



100 

 Liquid Excretions dried. 

 Uric acid - . - - . .59 



Earthy and alkaline phosphates, sulphates 

 and chlorides - - .' - .41 



100 

 If we compare the first of these results of Co- 

 indet with the constitution of ihe guano as it is 

 imported into England, we cannot fail to be struck 

 with the degree oi' decomposition which the latter 

 must have undergone— supposing it to have ori- 

 ginally resembled the solid excretions of the sea- 

 eagle. The quantity of phosphate of lime in the 



• The prevailing views on this subject, and the 

 reasons on which they are founded, are explained in 

 my ' Lectures on Agricultural Chemistry and Geolo- 

 gy,' part i. p. 248. 



latter, 6-13 per cent., is unusually large for the ex- 

 crement ol a bird ; but if we suppose the recent 

 gu ino in Its dry slate to have contained quite as 

 much, il would rptjuire 500 lbs. of the lailer to 

 give ihe quaniiiy of phosphate (29 3 lbs.) con- 

 tained in 100 lbs. of a (juality such as the one por- 

 tion i examined, and 700 pounds lo yield the 

 quiiniiiy ol phosphate (44 4 lbs.) contained in the 

 other. In o:licr words, Iroiii 1 5 to 1 7 only of 

 ol ihe original urgani animal matier remains in 

 the guaiio, as ii is imported into England, li pro- 

 bably reiaiiis even less, sinc^ i* has unquestiona- 

 bly absorbed from the air a considerable portion of 

 muisiure not supposed lo be present m the drop- 

 pings when recent and carel'ully dried. 



it is easy lo see therelore why the recent guano 

 should bring so much higher a price on the coast 

 of Peru ; why the<incieni Peruvians should have 

 so carelully collected ii, and should so religiously 

 have preserved the sea-lowl from desiruclion or 

 disturbance ; and why ihey should have lell the 

 ancient accumulations "comparatively undisturbed; 

 to be searched lor and excavated in these after 

 limes when the produce of the living birds has be- 

 come less al)undant or is less carelulJy collected 

 and preserved.* 



On the other hand, in the identity of the sub- 

 stances contained in guano with those always 

 ibund in the recent excretions of living birds, we 

 have tiiat evidence of a common origin — which 

 in a previous part of ihe present paper was stated 

 to lend an almost unnecessary confirmation to the 

 evidence there adduced in regard lo the source 

 from which the accumulations, on the shores of 

 Peru, have unquestionably been derived. 



One other remark I may here venture lo intro- 

 duce. We an- astonished — even geologists, who 

 are familiar with extended periods of lime, and 

 are accustomed to contemplate immense results 

 produced by the prolonged action of apparently 

 insignificant causes — even geologis's are struck 

 with the occurrence on the existing surface of the 

 globe of such vast accumulations of excremen- 

 litious matter: yet how are our ideas slill further 

 magnified in regard bo'h to the number of birds 

 necessary 10 deposiie ihem, and 10 the lapse of 

 time during which they must have been gather- 

 ing, when we learn that what now remains is not 

 — either in bulk or in weight — more than an 

 eighth or a tenth part of that which originally 

 fell from the flocks of living sea-fowl ! 



3. A most important part of the composition 

 of the guano is the quantity of phosphoric acid il 

 contains in combination with ammonia, wiih 

 soda, and chiefly with lime. All plants require 

 lor their healthy growth a portion of this acid in 

 combination with lime. All vegetable produc- 

 tions which unmixed are capable of feeding and 

 nourishing animals musi contain it, since from 

 their vegetable food all animals ultimately derive 

 those earthy and other phosphates of which so 

 great a part of their bones consists, and which 



* The comparative value of the recent droppings of 

 birds is shown by the price usually paid in Flanders 

 for pigeons' dung. It is there emplo3'ed as a top- 

 dressing for the flax, and the dung of 100 pigeons is 

 worth about 20s. a year for this purpose — (Sprengel.) 

 The injurious effect of recent goose-dung arises from 

 its falling on Ihe grass in too concentrated a slate. 

 When diluted by a shower of rain its influence is most 

 bcneflcial. 



