Plciiro-p/ifiii/nviia in Cattle 



543 



Council was no doubt passed on die 6th of 

 March 1868, restricting the movement of dis- 

 eased live stock in Ireland, but that Order, 

 although good as far as it goes, is still defec- 

 tive, and especially in leaving it to be carried 

 out by private individuals — to anybody, in fact, 

 and therefore to nobody — instead of entrusting 

 it to qualified official functionaries. Dublin, how- 

 ever, does not stand alone as a chief centre of 

 disease. It is much the same in all large 

 towns, and Professor Williams declared at 



the meeting of the Scottish Chamber, that 

 " he thought the market of Edinburgh was a 

 greater nest from which pleuro was propa- 

 gated throughout Scodand than any part of 

 Ireland ;" a strong testimony in favour of the 

 object sought by the Chamber, namely, the 

 separation of the different classes of cattle in 

 the public markets, held in or near large 

 towns. 



We must reserve the farther consideration 

 of the Directors' Report until our next. 



THE PROPER USE OF ARTIFICL4L MAXURES OX A FARM. 



A 



WRITER in T/ic /•;<'/(/ treats this subject in the 

 following manner : — This is a question of much 

 importance, especially in those districts ivhere the 

 nature of the cropping is exhausting. In the great 

 potato district of Yorkshire, for example, which we 

 quote as being more particularly in our mind, the large 

 area of potatoes, in addition to a full proportion of 

 corn, and the corresponding paucity of sheep stock, 

 render a large quantity of artificial manures absolutely 

 necessary, in order to maintain the fertility of our fields 

 and grow such crops as shall prove remunerative. 

 The theory of manures will be understood from a 

 brief consideration of the nature of our crops. If we 

 perform the simplest analysis of vegetable structure — 

 viz., by combustion, we shall find that the great 

 bulk disappears. This has been improperly called 

 the organic part, and consists in the plant of 

 various combinations of four simple elements — 

 carbon, hydrogen, oxygen, and nitrogen, \\-hich 

 as carbonic acid gas, watery vapour, and am- 

 monia, the products of combustion, have passed into 

 the air, there to accumulate for future plant food. 

 Carbonic acid gas exists in the atmosphere in the pro- 

 portion of four to six parts in every 10,000 of air, 

 whilst nitric acid and ammonia are found in still more 

 minute quantities. Small as those supplies appear, 

 they are sufficient for natural vegetation. The rain in 

 every shower brings down traces ; the dew conveys 

 the precious gases ; the earth absorbs directly 

 from the air. One of the chief values of the bare 

 fallow consists in the frequent exposure of a fresli 

 surface, which absorbs plant food from the air. So 

 considerable is the power of absorption and retention 

 possessed by most soils, that M. Barral, an eminent 

 French chemist, has calculated that a well-made fal- 

 low ensures a supply of nitrogen equal to a dressing 

 of 2 cwt. of Peruvian guano per acre. Cultivated 



plants, being in an abnormal condition, require more 

 of these organic materials than the natural supply ; 

 hence the importance of manures like well-made 

 farm-yard manure and Peruvian guano, or the 

 artificial, like nitrate of soda and sulphate of am- 

 monia, which are rich in nitrogen, the scarcest and 

 most important of the group. Returning to the pro- 

 ducts of our combustion, we find a small residuum in 

 the form of ash, often not exceeding 3 to 4 per cent, 

 of the whole ; this is the mineral, or, as it is usually 

 called, inorganic part of the plant, and, though so 

 limited in quantity, is absolutely necessary, forming as 

 it were the bony system of the plant. The minerals 

 are derived entirely from the soil, entering by the 

 rootlets in solution in water, and in no other wav. 

 The following bases and acids, variously combined, are 

 usually present — potash, soda, lime, magnesia, iron, 

 silica, phosphoric, sulphuric, and hydrochloric acids. 

 The presence of all in the plant is essential ; there is 

 no power, as was once supposed, of substituting one 

 for the other. The fertility of a soil is in proportion 

 not to the presence only, but to the presence in a suit- 

 able fonn for absorption by plants, of its rarest in- 

 gredients ; and just as the strength of a piece of tim- 

 ber is measured by its weakest part, so the 

 fertility of a soil is dependent on the propor- 

 tion of its most rare ingredients. Chemical ana- 

 lysis indicates that our ordinaiy soils contain abundant 

 food for hundreds of crops. Practical experience 

 proves that two or three crops in succession exhaust, 

 or more properly reduce the yield to the natural limits, 

 /.<'., the limits at which the necessary minerals are 

 eliminated. Mr Lawes has thrown light on this sub- 

 ject by his admirable series of experiments on the 

 growth of wheat, extended over a period of twenty 

 year^. A careful study of the results, which are fully 

 reported in the Journal of the Royal A^riadtiiral 



