274 CALX BETTER THAN QUICK-LIME. 



and, when crushed, form one of the richest and most convenient 

 manures in the world; They are shipped in quantities from the 

 continent of Europe, and latterly even from this country, to be sold 

 for manure in England. The fields of battle have been gleaned, 

 and their shallow graves emptied for this purpose : and the bones 

 of the ten thousand British heroes, who fell on the field of Water- 

 loo, are now performing the less glorious, but more useful purpose 

 of producing, as manure, bread for their brothers at home. 



There prevails a vulgar but useful superstition, that there is 

 "bad luck" in throwing into the fire anything, however small may 

 be its amount or value, that can serve for the food of any living 

 animal. It is a pity that the same belief docs not extend to every 

 thing that as manure can serve to feed growing plants and that 

 even the parings of nails and clippings of beards are not saved (as 

 in China) for this purpose. However small each particular source 

 might be, the amount of all the manures that might be saved, and 

 which are now wasted, would add incalculably to the usual means 

 for fertilization. Human excrement, which is scarcely used at all 

 in this country, is stated to be even richer than that of birds ; and 

 if all the enriching matters were preserved that are derived not 

 only from the food, but from all the habits of man, there can be no 

 question but that a town of ten thousand inhabitants, from those 

 sources alone, might enrich more land than can .be done from as 

 many cattle. 



The opinions here presented are principally founded on the the- 

 ory of the operation of calcareous manures, as maintained in the 

 foregoing part of this Essay (Chap. VIII.), but they are also sus- 

 tained to considerable extent by facts and experience. The most 

 undeniable practical proof of one of my positions is the power of 

 a cover of marl to prevent the escape of all offensive effluvia from 

 the most putrescent animal matters. Of this power I have long 

 made use, and know it to be more effectual than quick-lime, even 

 if the destructive action of the latter were not objectionable. 

 Quick-lime forms new combinations with putrescent substances, 

 and, in thus combining, throws off effluvia, which, though different 

 from the products of putrescent matter alone, are still disagreeable 

 and offensive. Mild lime on the contrary absorbs and preserves 

 everything or at least prevents the escape of any offensive odour 

 being perceived. Whether putrescent vegetable matter is acted on 

 in like manner by calcareous earth cannot be as well tested by our 

 senses, and therefore the proof is less satisfactory. But if it is 

 true that calcareous earth acts by combining putrescent matters 

 with the soil, and thus preventing their loss (as I have endeavoured 

 to prove in Chapter VIII.), it must follow that, to the extent of 

 such combination, the formation and escape of all volatile products 

 of putrefaction will also be prevented. 



