tmm 



* die -n* -rtk 1 the wood oi the Oak on die 

 L * U drf**** only 2 per cent., while m the sap- 

 * e wOak he obuiiu-d 7 | per tent Similar 

 ware found in aev«J other plant*- It is, 

 piebaUe, tlutf the preteno* of sil a is not of 

 r^T^JJAnoTfor the perfect cultivation of many 

 •g-^i tli^r in reality it is more frequently absorbed 

 KTiahUe forms by the roots of plants, as lias been 

 m w dj apposed to be the case In its roso table 

 ia water aa it is very frequently found m soils, it 

 ^tjw^ much to give the plants a suitable habitat or 

 *^2swI*oe in the ground, and thus acts, by means of 

 |??32aMoperties, very beneficially on the soil, giving 

 to kthe ligtoeas requisite for vegetation. It obviously 

 jjVwrt, { rom these circumstances, how requisite it is, in 

 Si ^nalvsis of soils, to distinguish from each other the 

 jjLpos forms of the silica under which it occurs in land ; 

 M hi tn f urn> ut ^ uu1, if MmmuDic ** 11 to the soil, 

 tTili fJMr : - 1] V aad physically, quite different properties 



from what it does when occurring in land in its 

 divided drte, either ima or in combination with al 



(or 



I 



Alumina 



finely 

 umina 

 earth of clay). Old analyses of soils, even 

 i^dTbr distinguished chemists, in which merely the 

 vmxmtof the silica in the soil is given in general terms, 

 wntboui a particular statement of its different forms of 

 occamace, have often, on this account, very little value 

 in an agricultural point of view. 



H All-* a (or the pure earth of clay), 

 apptars W> pass over into the mixture of the juices of 

 jLantoniuch more rarely than silica. Berthier could 

 fid no tm of it in the ashes of 28 different kinds of 

 wood that he investigated, although this earth was found 

 to be often contained in large quantities by the soil in 

 which the trees furnishing those specimens of wood had 

 been grown. Saussure also found, in the course of his 

 investigations into the nature of the ashes of several 

 plants, that alumina very seldom occurred in them, and 

 much more rarely than silica, lime, and magnesia : this 

 confirms the correctness of the opinion, that alumina 

 occurs in land but seldom in a state of solution. Not- 

 withstanding tins little tendency to solubility, alumina, 

 in consequence of its physical properties, forms one of 

 the more essential ingredients of the soil, and is of 

 great importance to vegetation. In its combination 

 with silica, as clay, it has the property of giving to land 

 the proper consistence ; of attracting to itself hydro- 

 Bcopically the moisture of the air in a higher degree 

 than other earths ; of absorbing in this moistened state 

 the oxygen of the atmosphere ; and of collecting within 

 itself, and combining the particles of humus in greater 

 amount than is effected by other ingredients of the soil. 



Clit con^Nts of an intimate combination of alumina and 

 fiBca, with more or less oxide of iron, and here and there 

 ako with a smaH proportion of the oxide of manganese. The 

 combination of these substunMB is commonly so intimate that 

 dilated acids have n-.>t the power to disturb it; but sulphuric 

 add, allowed to act on them for a longer time at a boiling 

 heat, dissolves the a'umma ani the metallic oxides, while the 

 •iHca mains undissolved. Clay is generally mixed up with 

 several per oentages of finely-divided sand and tine silica, 

 which .may be separated [from it, before it? analysis, by re- 

 pepeated boilinjr with water and careful decantation. Pure 

 clay does not effervesce with acids ; diffuses, when breathed 

 upon in a dry state, a strong- earthy odour; adleres to the 

 tongue, quickly absorbs water, oils, and fatty substances ; it 

 remains for a certain time lightly suspended in water, which 

 it readers muddy, but from which it perfectly separates again, 

 by subsidence, when left at rest. Ot this water it retains, in 

 iti finer [state, from 70 to 71 per cent., without allowing it to 

 drop away from it; in a compact and moderately tuoi-tened 

 state water penetrates but slowly into its interstices ; it dries 

 up slowly, and in so doing shrinks into a smaller space, 

 leaving many cracks and fissures throughout its substance ; 

 it readily takes up humus and humic acid in considerable 

 quantities, which seem to combine with it, partly in a chemical 

 meaner, and partly through adhesion in a physical one, in 

 consequence of which it remains for a long time fertile, after 

 it has been once properly penetrated by humus-particles and 

 other earths, which communicate to it "the requisite lightness 

 for cultivation. In the wet state it forms land of a very tena- 

 cious character, and difficult to work, indicating a great 

 adhesion to the field-implements employed ; when dried up, it 

 is hard and can scarcely be penetrated by the implements or 

 the roots of plants ; in this purer torm, therefore, it is un- 

 suitable for vegetation. By means of frost, and through 

 freezings in the wet state, its consistence i6 much improved ; 

 it becomes in consequence much lighter, the water contained 

 within its interstices becoming crystallised, and rending 



mder the particles of the clay by its expansion ; but it easily 

 loses this lightness again when worked in a wet state. On 

 exposure to a red-heat it permanently changes its properties, its 

 whole nature becomes altered, it generally obtains, by a higher 

 dejpree of oxidation of its oxide ot iron, a deeper, and often red 

 colour, its power of retaining water being considerably dimi- 

 nished ; it can now be retained in suspension by water only to a 

 small amount : it has lost, to a considerable extent, its great 

 adhesion to field-implements, and the properties of a tenacious 

 fceswj clay, forming a soil more nearly approaching to a light, 

 dry, sandy soil. The alumina and silica have become changed, 

 by the red-heat, into a half-vitritied state, similar to that of 

 burnt brick. Clay is not alwajs composed of Bilica, alumina, 

 oxide of iron in the same proportions : silica, indeed, con- 

 •autly forms the principal ingredient, but its amount varies 

 several per centagee, as the following analyses of several kinds 

 of clay will show. 



lu the Ifin nra ana*,)**! ujliu* oi iruu >\..» profc*blj not 



separated from the alumina. We may erefore assume, on 



and 



4 

 the 



----■—• — - - _--_ _ _ -(' ^^ w ■ — ~ ■ — — — — 



incidental ingredients of clay, which are ofteu contained In it 

 as accidentally mixed particles ; thee, betides sand, consist 

 often oi lime and magnesia, with strongly combined w*t*r : 

 the amount of water in cUy, which has beta merely dried in 

 the open air, amounts to 0, 8, 10, to 14 per cent., and is 

 nly driven off by exposure of the clay to a red. hear 

 The various colours of the varieties of clay deserve m ss rti s u ing. 

 Thev are c asioned most frequently by iron in difiet it 



" disembow 



vegetable remains. The greenish and bluelsh colours result 

 neralhy from the hydrated protoxide of iron, the brown ones 

 trom protoxide of iron ; the red from peroxide of iron ; and the 

 yellow from hydrated oxide of iron ; the black colour of clay is 

 often occasioned by much carbonised humus-particles, and some- 

 times also by the admixture of oxide of manga mere. The white 

 clays contain commonly the least admixture ; they are capable, 



tag 



_ a," Mr. J. 1" ivuian, oi Mua 



trose, — the m trial " assumes some importance. It is now 

 "Ireland and Scotland v. England/ 1 with heavy odds 



against the latter. Unforruna ly 1. wlio repros m in 

 my humble person this "Laud of the Brave, 3 ' am at 

 present unable to "prove my case." 1 am no farmer ; 

 never followed the plough ; never detected, never read, 

 ver heard of skylarks living in spring-time on salads 

 of delicate, succulent Wheat-grass ; never fired at nor 

 shot these " rogues in grain," when so detested ; nor 



them afterwards to find " damning 

 proof" concealed within, to tell of such moral guik* 

 All I can conscientiously do, therefore, is to speak what 

 I know of their general character ; of the * high • 

 position they hold in the world at large, — I have already 

 done so : and to throw myself on the mercy of the 



judice adfmc 



Twv wit- 



lay 



nominations, according as tliej more nearly approacn to me 

 pure rich clay, or ossstain intermixed with tbein a variable 

 quantity of tine sand. Crume was the first who proposed 

 definite term9 for these varieties, which we here retain. To 

 prevent contusion, as these varieties are not known to the 

 cultivator in even- district in Germany, under the same terms, 

 we will define each kind more closely. The rich, or fat clay is 

 that which approaches most nearly to clay in Its pure state ; we 

 understand by it, a*clay, from which, by boiling and decanta- 

 tion, an amount of from 5 to 15, that is, an average of 10 per 

 cent., of sand, mny be separated : to this variety btloug man> 

 of the pottery clays, the colours of which are as various as 

 those tit pure clay. It forms a very heavy soil, capable of 

 absorbing about GO per cent, of water into its interstices ; in 

 order to give to it the lightness requisite tor agricultural pur- 

 poses, from 20 to 30 per cent, at least, of coarse sand, are 

 necessary ; if the proportion of the coarser *and is raised from 

 30 to 50 per cent., so that the quantity of the sand is about 

 equal to that of the lich clay itself, a very good mixture of soil 

 la formed, which has neither too strong nor too small a con- 

 sistence tor field operations. When the proportion of the 

 coarse sand, however, amounts to 60 and 70 per cent., the *oil 

 assumes the properties of a sandy soil. Clay-lainis are very 

 much improved in value wh n they contain a few per- 

 centages of carbonate of lime, or chalk. Loamy clay 

 differs from pure clay in the greater amount of sand 

 it contains; we understand by this term, a clay, out of 

 which, by boiling and decantation, may be separated from W 

 to 30 per cent., or on an average of 24 per cent., of fine sand : it 

 has less tenacity and lubricity, and a smaller amount of 

 cohesion, than rich clay; it takes up about 50 per cent, of 

 water; it shrinks less on drying than lick clay. By proper 

 aoTmixiure wit i sand, humus, and lime, it becomes con- 

 verted, more easily than rich clay, into a lertile soil. 1 he 

 24 per cent, of fine Band already contained in it, are, in refer- 

 ence to its influence on the lightness of tne soil, at least equi- 

 valent to 15 per cent, of coar»er sand. By the poor or hungry 

 clays, we understand, in agricultural works, an i in many lto- 

 vinces of Germany, the poorest clays, which contain from 80 

 to 60 per cent., or on an average 45 per cent, of fine sand, mixed 

 with them. Through their great amount of sand and silica, 

 they have little tenacity and cohesion, take up only 40 per ceut. 

 of water, and dry in the air without an> considerable change 

 of volume. They already possess so much looseness, that no 

 further addition of sand is necessary to render them capable 

 of cultivation ; they are often liable to suffer for want of 

 sufficient moi^iure. In the language of miners, and in common 

 discourse, on the contrary, a loamy clay is often understood 

 to signify a very rich clay, which most nearly approaches to 

 pure clay. 



g at once detected by the nesses onlv have appeared ; and they represent Scotland 

 known under different de- and Ireland. I ham advocated, as yet, the cause of the 



English Lark, believing hkn honest, and Kke the rook 

 the farmer's best of friends* Let but a respectable 



witness for England appear against me, and the verdict^, 

 alas ! must be for the plaintiffs. I hope, however, it 

 will not be with " immediate execution," but that 



Home Correspondence 



Sheep folded on Grass. — I have lost several ewes 

 within the last two months, they have been in a good 

 pasture field in the day, and folded on a part of the 

 same field at night, and have had a supply of Turnip -. 

 and about £ lb. of Beans each daily. The greatest 

 part of the field was covered well over with farm-yard 

 manure in December, and my man thinks that this is 

 the cause of their dying as they do, suddenly ; what is 

 your opinion on this subject? Oldham. [We do not 

 consider the cause you suppose as by any means 

 probable. The nature and cause of the disease can be 

 best ascertained by examining the body carefully after 



death. W.C.S.] 



Management of Steam Engines. — The following cuts 



should have been published with iC WYs " paper on this 



subject. They are a transverse and longitudinal section 



of the Cornish boiler. In both A is the water-line ; in 



the circular transverse section B C are the circular Hue 



through the boiler in which the fire-place is — B being 



A 





M 



1 



D 





• judgment may be respited until next term " (the larks^ 

 — many of them, I fear, will be spitted, by your two 

 zealously-affected correspondents, before they are 

 respited by the judges.) " A Shilmaher " and Mtw 

 Foreman are both such pleasant gentlemen, and write 

 so well and so good-naturedly withal, that it is impos- 

 sible to feel otherwise than friendly towards them, or to 

 gainsay what they so clearly assert. They state their 

 grievances very fairly, and, as Mr. Foreman facetiously 

 remarks, pay perhaps rather " dearly for their wlimtle" 

 But what a whistle ! Was ever any whistle heard like 

 unto it? Never! And yet surely the voices of tho 

 larks which inhabit the corn-fields of Ireland and Scot- 

 land cannot equal those we are accustomed to hear in 

 "nierrie England!" Surely not; or a few extr* 

 bushels of Wheat — now said by the farmers to be worth, 

 nothing — would never be a consideration of important 

 The dissentients shall soon hear our English lark, and 

 judge for themselves. "A Shilnialier" hints that he 

 will pay a visit, anon, to our "World's Great Fair;*' 

 and that while in our gay city he will honour me with, 

 a friendly call. Of course he will. I shall fully expect 

 him, and greet him with a hearty welcome on hisarrival. 

 Let Mr. Foreman follow suit in this goodly move ; and 

 let us all three, over wine and Walnuts, Pine-apples and 

 sherry cobbler, argue onee more, deliberately, humanely, 

 and philosophically, the case of the poor skylark — 

 Heaven's special favourite ! Not longer ago than Sunday 

 last, as I stretched far away among the Surrey hills, 1 

 saw my protege, crest erect, 



94 From his moist cabinet, mount up on high f 



and the music he discoursed was so eloquent, that I 

 thought if u A Shilmalier " was by my side, I could have 

 converted him. Indeed I question, if I read his charac- 

 ter aright, whether his "spring crops of Wheat, Rye, 

 Barley, Oats, Beans, Peas, and Vetches," would not, at 

 the time I speak of, have been placed at the free disposal 

 of this merry, innocent rogue, and his associates. Mr. 

 Foreman recommends me to use a good telescope in my 

 rambles, and so " take a sight w of the larks' consump- 

 tive habits.* He marvels, too, at my want of ornitho- 

 logical lore ; and advises me, by ocular demonstration, 

 to convince myself of what larks really do eat in the way 

 of grain. As regards the larks of Scotland, I willingly 

 confess my ignorance, and most readily take his word ; 

 but, if you please Mr. F., pendente lite, we will let the 

 food of the wild English lark remain an u open question." 

 William Kkld,New Road, Hammersmith, M v§ 1. 



Game. — In the last Number of the Agricultural 

 Gazette, p. 252, is a long article headed " Game," in 

 which the writer, like too many writers and talkers of 

 the present time, anathematises landlords for keeping 

 game on their own lands. Now, I am no sportsman* 

 but I have passe3 through a pretty long life, and as far 

 as my experience has gone, and it Jhas been of con- 

 siderable extent, in nineteen cases out of every twenty^ 

 game-preservers havs made the best landlords I hare 

 known, and tenants have done the best nnder them. 

 There are, or there may be, I admit, some few exceptions 

 to this general rule ; but still I maintain that the rule is 

 a general one. I know that it is a very popular subject 

 to rave against landlords ; and equally as unpopular a 

 one to write a word, or speak a word in their defence. 

 But is the game in this Country generally injurious or 

 beneficial to the cultivators of the lands of it I — this is 





Kisdsof Clay, 



White. r J 



Grey potter's- clay '." 

 White potter's-clay 



of Abondant 



White clay of Reu- 

 hausea in the 

 'nni limestone ... 



••WH clay of Ar- 

 eueii, near Paris 



Grey potter's-clay of 



TiUendorf 



D *rk-grey day of 

 Bofiryl 



Bed clay of the 

 fceuper- formation 



jj*e "Analyses .. j 



Silica. 



Alumina. 



63.0 

 60.0 



58.8 



56.3 

 63.0 

 G8.5 

 58.0 

 62.3 



37.0 

 40.0 



41.2 



38.6 

 32.0 

 30.3 

 36.2 



27.8 



Oxide 

 of Iron. 



■ •« 



Chemists 



• .. 



4.9 

 4.0 

 1.1 

 5.8 



7.9 



Kirwan. 

 Vauquelin 



Berthier. 



Chr. Gmelln 



Gazeran. 



Klaproth. 



Schooler. 



Schiibler. 



61.6 



32.9 



4.6 



the fire and C the ash-pit, the line between them occu- 

 pying the position of the fire bars. In the longitudinal 

 section B is the ash-pit, C D the fire-place, C being the 

 "dead plate" on which the coal is gradually heated for 

 burning at D. Below B the cut should have given the 

 section of that portion of the boiler below the ash-pit. 



Case of"TJte Skylark /' a Demurrer, and Motion for 

 a New Trial. — When a man has a friend whom he dearly 

 loves, how natural is it for him to plead earnestly in his 

 friend's behalf when he hears him spoken against — par- 

 ticularly when he is, or is supposed to be, innocent of 

 the crime laid to his charge ! In this latter belief, I 

 confess I recently espoused the cause of the hapless 

 skylark, imagining him to be guiltless of chewing the 

 cud of the young germinating Wheat, Peas, &c, — at all 

 events with so alarming an appetite, clearly indicative 

 of his having what we English call "the wolf" m his 

 stomach. Since, however, " A Shilmalier " returns to 

 the charge with redoubled energy, and with multiplied 

 .viflvanpaa nml is now moreover backed bv another 



! 



am aware that I shall be condemned 

 by all the apron-string farmers in this country, and by 

 too many who ought to know better, when I pronounce 

 that game preservers, taking them as a body, are great 

 benefactors to land cultivators ; and I go further and 

 add, that were landowners to extirpate the game off 

 their lands, instead of preserving it, they would inflict 

 a sore evil on their country. Not, however, be it under- 

 stood, that I am referring to the money value of game* 

 or of its forming an article of luxury for the tables of 

 the wealthy ; but I am referring to the real benefit that 

 game confers upon the cultivators of the soil, and to 

 that only. With these few remarks, Mr. Editer, I close 

 this subject for the present ; but should any of your 

 correspondents like to discuss it further with me, and wul 



* I am indeed plad that this question has been broached. 

 It will tend to throw a light on a dark subject, not yet 

 fathomed. Veritas in ptiteo* Larks have hitherto been re- 

 garded by bird-fanciers and naturalists as jofi-billed birds,-- 

 not granivorous ; and when caged, hare been fed accordingly 

 Yet hare they thriven marvellously ! How w this ? 



