Retrospective Criticism. 515 



to any distance, and forms a manure next in richness to bones. In gardens 

 it may be used as a top dressing to culinary vegetables, and as an ingredient 

 in the composition of vine borders. Animalised carbon consists of nightsoil 

 of great age ; it is sent to different parts of Europe from Copenhagen, where 

 it has accumulated during ages in immense pits and heaps, which some years 

 ago were purchased from the city by an Englishman. It is an exceedingly 

 rich manure." 



There is a good deal of loss in mixing quicklime with substances putrefying 

 rapidly. The lime seizes on the carbonic acid of the substances, forming an 

 insoluble carbonate of lime ; and the extraction of the carbonic acid hastens 

 decomposition. Ammonia, being expelled in greater quantity, is always the 

 result of the application of quicklime, as may be detected by the smell. It 

 may be useful, in a commercial way, to sustain a great loss for the purpose of 

 making the article negotiable ; but, where convenience will admit, rapidly 

 putrefying substances are most economically prepared by mixing with earth 

 or compost, and keeping cool by turning. Where they have to be carried far, 

 sulphuric acid (vitriol), where cheap, will disinfect most economically ; or, if 

 cheaper, sulphate of lime (gypsum) ; or sulphate of iron (copperas), if very 

 cheap. Quicklime is most useful with substances that decay slowly ; its 

 avidity for carbonic acid causes it to be extracted from the slowly decom- 

 posing substances it is mix^d with, as couch grass, roots, weeds, &c, and 

 hastens their decomposition. (See 195.) 



" 189. Bones, though a manure of animal origin, depend for their effects a 

 good deal on their mineral constituents. Next to nightsoil, bones are perhaps 

 the most valuable of all manures. Chemically, they consist of gelatine, albu- 

 men, animal oils, and fat, in all about 38 per cent ; and of earthy matters, 

 such as phosphate of lime, carbonate of lime, fluate of lime, sulphate of lime, 

 carbonate of soda, and a small quantity of common salt. In consequence of 

 the animal matters which they contain, crushed bones, when laid in heaps, 

 very soon begin to ferment, and when buried in the soil previously to being 

 fermented in heaps, the putrescent fermentation goes on with great rapidity. 

 In gardens they should seldom be used without being broken small, and 

 fermented in heaps for several months. Bones are valuable as a specific 

 manure, because they contain phosphate of lime, which is an ingredient 

 common to a great many cultivated plants, both of the field and of the garden. 

 Bone manure, if used on the same soil for a number of years, is found to lose 

 its effect ; the reason of which is inferred from one cause of their excellence, 

 viz. that the animal matter which they contain acts as a ferment or stimulus 

 to the organic matter already in the soil, by which means this organic matter 

 becomes sooner exhausted than otherwise would be the case. The remedy 

 for this evil obviously is, to discontinue the use of the bones, and to supply 

 putrescent manure, such as stable-dung." 



When there are not sufficient of the phosphates in the soil for bones, their 

 application will have a more powerful effect at first, than after long continu- 

 ance has caused the soil to abound in these. 



" 193. Inorganic or mineral manures are, chiefly, lime in a state of chalk or 

 carbonate, gypsum or sulphate, marl in which carbonate of lime is mixed with 

 clay, saltpetre, kelp or mineral alkali, and common salt. The organic manures, 

 as we have seen, act by supplying plants with the elements of which they are 

 constituted, viz., carbon, oxygen, hydrogen, and azote or nitrogen ; but the 

 mineral manures contain none of these elements, and hence, according to 

 most agricultural chemists, they must act beneficially on some other principle. 

 This principle may be stated to be the rendering more soluble of the organic 

 matters already in the soil in most instances, and in some cases rendering 

 soluble matters insoluble, so as to diminish excessive fertility, and prepare a 

 reserve of the fertilising principle for future use. Quicklime, for example, 

 effects the first of these objects, and slaked lime the second. According to 

 some writers, inorganic manures also act specifically ; alkaline matters being 

 found in all, and some sorts in many plants." 



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