1838] 



FARMERS' REGISTER. 



615 



cakes towheafen bread ; finding ihat this kind of 

 nourishment enables them to support their sirength 

 and perlbrni their kibour better. In summer, 

 they say oat-cake heats ihem, and ihey then con- 

 sume the finest wheaten bread they can procure. 

 Even the skin of the kernel of oats probably has 

 a nourishing power, and is rendered partly soluble 

 in the stomach with the starch and gluten. In 

 most countries of Europe, except Britain, and in 

 Arabia, horses are fed with corn ofdiH'erent kinds, 

 mixed with chopped straw ; and the chopped straw 

 seems to act the same part as the husk of the oat. 

 In the mill 14 lbs. of good wheat yield on an 

 average 13 lbs. of flour ; the same quantity of 

 barley 12 lbs., and of oats only 8 lbs. 



In the south of Europe, hard or thin-skinned 

 wheat is in higher estimation, than soft or thick- 

 skinned wheat ; the reason of which is obvious, 

 from the larger quantity of gluten and nutritive 

 matter it contains. I have made an analysis of 

 only one specimen of thin-skinned wheat, so that 

 other specimens may possibly contain more nutri- 

 tive matter than that in the table ; the Barbary 

 and Sicilian wheats, before referred to, were thick- 

 skinned wheats. In England, the difficulty of 

 grinding thin-skinned wheat is an objection ; but 

 this difficulty is easily overcome by moistening the 

 corn.* 



LECTURE IV. 

 ON soils: their constituent parts, on 



THE analysis OF SOILS. OF THE USES 

 OF THE SOIL. OF THE ROCKS AND STRATA 

 FOUND BENEATH SOILS. OF THE IMPROVE- 

 MENT OF SOIL. 



No subjects are of more importance to the farm- 

 er than the nature and improvement of soils ; and 

 no parts of the doctrines of agriculture are more 

 capable of being illustrated by chemical inquiries. 



Soils are extremely diversified in appearance 

 and quality ; yet, as it was stated in the introduc- 



* For the lollowing note on this subject I am in- 

 debted to the kindness of the Right Hon. Sir Joseph 

 Banks, Bart. K. B.:— 



Information received from John Jeffrey, Esq., his Ma- 

 jesty's Consul- General at Lisbon, inansiver to Que- 

 ries transmitted to him, from the Comm. of P. C. for 

 Trade, dated Jan. 12, 1812. 



To grind hard corn with the mill-stones used in 

 England, the wheat must be well screened, then 

 sprinkled with waterat the miller's discretion, and laid 

 in heaps and frequently turned and thoroughly mixed, 

 which will soften the husk, so as to make it separate 

 from the flour in grinding, and of course give the flour 

 a brighter colour; otherwise the flinty quahty of the 

 wheat, and the thinness of the skin, will prevent its 

 separation, and will render the flour unfit for making 

 into bread. 



I am informed by a miller of considerable experi- 

 ence, and who works his mills entirely with the stones 

 from England or Ireland, that he frequently prepares 

 the hard Barbary corn by immersing it in water in 

 close wicker baskets, and spreading: it thinly on a floor 

 to dry ; much depends on the judgment and skill of 

 the miller in preparing the corn for the mill according 

 to its relative quality. I beg to observe, that it is not 

 from this previous process of wetting the corn that the 



tory lecture, they consist of different proportions 

 of the same elements ; which are in various states 

 of chemical combination, or mechanical mixture. 



The substances which constitute soils have been 

 already mentioned. They are certain compounds 

 of the earths, silica, lime, alumina, magnesia, 

 and of the oxides of iron and manganesum ; ani- 

 mal and vegetable matters in a decomposing state, 

 and saline, acid, or alkaline combinations. 



In all chemical experiments on the composition 

 of soils connected with agriculture, the constitu- 

 ent parts obtained are compounds ; and they act 

 as compounds in nature ; it is in this state, there- 

 fore, that I shall describe their characteristic pro- 

 perties. 



1. Silica, or the earth of flints, in its pure and 

 crystallized form, is the substance known by the 

 name of rock crystal, or (Jornish diamond. As 

 it is procured by chemists, it appears in the form 

 of a white impalpable powder. It is not soluble 

 in the common acids, but dissolves by heat in fixed 

 alkaline lixivia. It is an incombustible substance, 

 for it is saturated with oxygen. I have proved it 

 to be a compound of oxygen and the peculiar 

 combustible body which I have named silicum ; 

 and from the experiments of Berzelius, it is pro- 

 bable that it contains nearly equal weights of these 

 two elements.* 



2. The sensible properties of lime are well 

 kwown. It exists in soils usually united to car- 

 bonic acid, which is easily disengaged from it by 

 the attraction of the common acids. It is some- 

 times found combined with the phosphoric and 

 sulphuric acids. Its chemical properties and 

 agencies in its pure state will be described in the 

 lecture on manures, obtained from the mineral 

 kingdom. It is soluble in nitric and muriatic 

 acids, and forms a substance with sulphuric acid 

 diflicult of solution, called gvpsum. It is not so- 

 luble in alkaline solutions. It consists of one pro- 

 portion. 40 of the peculiar metallic substance, 

 which I have named calcium; and one proportion 

 15 of oxygen. 



weight in the flour of hard corn is increased ; but from 

 its natural quality it imbibes considerably more water 

 in making it into bread. The mill-stones must not be 

 cut too deep, but the furrows very fine, and picked in ' 

 the usual way. The mills should work with less ve- 

 locity in grinding hard corn than with soft, and set to 

 work at first with soft corn, till the mill ceases to work 

 well ; then put on the hard corn. Hard wheat always 

 sells at a higher price in the market than soft wheat, 

 on an average of ten to fifteen per cent. ; as it produces 

 more flour in proportion, and less bran than the soft 

 corn. 



Flour made from hard wheat is more esteemed than 

 what is made from soft corn ; and both sorts are ap- • 

 plied to every purpose. 



The flour of hard wheat is in general superior to that 

 made from soft; and there is no difl'erence in the pro- 

 cess of making them into bread ; but the flour from 

 hard wheat will imbibe and retain more water in mak- 

 ing into bread, and will consequently produce more 

 weight of bread : it is the practice here, and which I 

 am persuaded it would be advisable to adopt in Eng- 

 land, to make bread with flour of hard and soft wheat, 

 which by being mixed, will make the bread much 

 better. 



(Signed) John Jeffrey. 



* According to the latpr experiments of Berzelius, 

 silica consists of 484 inflammable basis, and of 51'6 

 1 oxvgen. — J. D. 



