INTRODUCTION. 1281 



ascertaining the manures proper for being applied to them, but also for knowing their 

 application to the feeding or fattening of animals. 



Hence, also, no system of agriculture or horticulture can be considered complete 

 which does not give an analysis of the chemical constituents, not only of the plants of 

 cultivation, but of the weeds of the locality. In a word, the chemical constituents of 

 every individual plant are just as essential tobe known as its physiology and systematic 

 character; and indeed a great deal more so. A century hence, or in less time, it will 

 be wondered bv scientific cultivators how the present generation could go on without 

 this knowledge. 



26. Warmth, to a certain extent, is equivalent to food ; and hence the great benefit 

 derived from sheltering cattle during winter. 



27. Exercise is for the most part a waste of food, and hence the advantage of stall- 

 feeding cattle, and confining pigs and poultry in a limited space ; it does not follow 

 from this, however, that confinement should be carried so far as to render the flesh of 

 the animals unwholesome. 



28. In the case of milch cows, rich pastures, or other food abounding in carbon, 

 produce the greatest proportion of butter ; while poor pastures, by requiring the cow to 

 take more exercise, increase the proportion of the caseous part of the milk. 



29. The various new manures which have been introduced are either of organic or 

 inorganic origin. The action of inorganic manures, such as nitrate of soda, common 

 salt, etc., is not uniform, and in some cases is not perceptible; but the action of organic 

 manures, such as guano, poudrette, rape or oil-cake, and vegetable alkalies, such as 

 potash, is certain, and always beneficial if not applied in too great doses. 



30. All clays contain potash, and also all soils produced from rocks containing 

 felspar, zeolite, albite, and mica ; and hence one cause of the value of basaltic and 

 granitic soils. 



31. The application of burnt lime to clay, independently of other effects which it 

 may produce, liberates potash. 



32. The action of burnt clay (which generally contains oxide of iron) to soils, inde- 

 pendently of its mechanical properties, is as an absorbent of ammonia from the atmo- 

 sphere. 



33. The addition of clay to sandy soils containing calcareous matter, increases the 

 quantity of potash which they contain; but if the sand contains no calcareous matter, 

 it merely improves their mechanical texture. 



34. The ammonia of liquid or other manures may be fixed by gypsum or sulphuric 

 acid ; or-, in default of these it, may be prevented from evaporating by mixing with soil 

 or diluting with water. In general the most convenient and economic mode for the 

 British agriculturist is to mix it with farm-yard manure, or, what is better in our 

 opinion, plenty of surface soil. 



35. The chief practical advantages which have as yet resulted from the recent dis- 

 coveries in chemistry, as applied to agriculture, are, the employment of saline manures, 

 and the recognition of their importance, the mixing of azotised (nitrogenised) with 

 unazotised (unnitrogenised) food in feeding and fattening cattle, and the procuring 

 greater warmth for the domestic animals of the farm. 



36. The most useful practices which have obtained extended diffusion within the last 

 ten years are, the frequent drain system, long practised in Essex and Suffolk, but recently 

 brought conspicuously into notice by Mr. Smith of Deanston, the use of draining- 

 tiles instead of stones, the use of the subsoil plough, and of the cultivator as a sub- 

 stitute for the plough in various cases, the greater eagerness to procure improved 

 implements, machines, and buildings generally, the mixture of soils, the greater value 

 set on urine and liquid manure generally, the use of single horse carts, the selection of 

 improved varieties both of animals and plants, and the employment of land agents con- 

 versant with agriculture, instead of lawyers or others who have little or no agricultural 

 knowledge. 



The details which have led to the above summary will be found in Liebig's Organic 

 Chemistry, and Animal Chemistry; Johnston's Agricultural Chemistry ; Trimmer's 

 Practical Chemistry for Farmers and Landowners ; Solly's Rural Chrmistry ; Dr. Play- 

 fair's Lectures on rearing and feeding Cattle, published in the Journal of the Royal 

 Agricultural Society, vol. iv. ; Donaldson's Manures, Agricultural Grasses, and General 

 Ma7iagement of Landed Property, &c. The greater part of this Supplement consists 

 of extracts from these works ; and from the Quarterly Journal of Agriculture, the British 

 Farmer's Magazine, the Gardeners Chronicle, and the Gardener's Magazine. 



J. C. L. 

 Bayswater, August, 1843. 



4 N 



