MANURES. 



MANURES. 



'000 parts of horse-dung, dried in a temperature 

 of 100, absorbed by exposure for three hours 

 to air saturated with moisture of the tempera- 

 ture 02 



1000 parts of cow-dung, under the same circum- 

 stances, absorbed ------ 



1000 parts of pig-dung - 



1000 parts of sheep-dung - 



1000 parts of pigeons' dung - 



1000 parts of a rich alluvial soil, worth 2 guineas 

 per acre -------- 



The following were dried at 212. 



1000 parts of fresh tanners' bark - 



1000 parts of putrefied tanners' bark - 



lOOi' ptirts of refuse marine salt, sold as manure 



1000 parts of loaf ------ 



1000 parts of luirnt clay - - ... 

 1000 parts of coal ashes - - - - - 



1000 parts of lime ------ 



1(100 parts of sediment from salt parts 



1000 parts of crushed rock-salt - 



1000 |i:trls of gypsum ------ 



1000 parts of chalk ------ 



There is reason to conclude that some ma 

 nures act as stimulants to plants, and excite 

 them to a more vigorous growth : it is proba- 

 ble that the saline matters of farm-yard com 

 post operate in this way, and that saltpetre and 

 other saline fertilizers do the same. I have 

 often had occasion to notice the increased 

 luxuriance and productiveness of fruit trees 

 such as cherries and pears, by the application 

 of common salt. (Essay on Salt, p. 4.) Priestley 

 made similar observations. " It seems pretty 

 plain," to give the words of Dr. Thomson, 

 "that the vessels of plants are made to contract 

 by various stimuli: the experiments of Coulomb 

 and Saussure render this probable ; and an 

 observation of Dr. Smith Barton makes it next 

 to certain. He found that plants growing in 

 water vegetated with much greater vigour, 

 provided a little camphor was thrown into the 

 water. (Chemistry, vol. iv. p. 338.) 



Of the organic manures, the richest abound 

 in azote, or nitrogen ; and, in fact, there are, 

 as Dr. Liebig observes (Organic Chem. p. 70), 

 "numerous facts showing that the formation 

 in plants of substances containing nitrogen, 

 such as gluten, takes place in proportion to the 

 quantity of this element, which is conveyed to 

 their roots in the state of ammonia, derived 

 from the putrefaction of animal matter. Am- 

 monia, which is composed of 14-15 of nitrogen 

 and 1 of hydrogen, is capable of undergoing 

 such a multitude of transformations, when in 

 contact with other bodies, that in this respect 

 it is not inferior to water, which possesses the 

 same property in an eminent degree.' 

 employment of animal manure," he adds (p. 

 86), "in the cultivation of grain, and the vege- 

 tables which serve for fodder to cattle, is the 

 most convincing proof that the nitrogen of 

 vegetables is derived from ammonia, 

 quantitv of gluten in wheat, rye, and barley is 

 very different: these kinds of grain also, even 

 when ripe, contain this compound of nitrogen 

 in very different proportions. Prou 

 French wheat to contain 12-5 per cent, of 

 gluten: Vogel found that the Bavarian con 

 tained 24 per cent.: Davy obtained 19 per 

 cent, from winter, and 24 per cent, from sum- 

 mer \vheat, from Sicilian wheat 21, and from 

 Barbary wheat 19 per cent. The meal of 

 Alsace wheat, according to Boussingault, con 

 tains !* per cent, of gluten; that of wheat 

 772 



