252 FARM-YARD DUNG. 



with boiling distilled water, and thrown upon a filter. The filtered 

 fluid is reduced by evaporation to a very small quantity, which is 

 then poured into a test tube, and a little pure hydrochloric acid is 

 added ; some particles of leaf gold are then introduced, and the 

 fluid is stirred with a glass rod. If any nitrates have been present, 

 the particles of gold are speedily dissolved. 



Having now described the circumstances which determine, and 

 the phenomena which accompany the decomposition of dead or- 

 ganic matter, I have next to treat of manures in particular, of their 

 preparation, of their application, and of their relative values. 

 Speaking generally, the manure which is derived from the dejec- 

 tions of animals, supplied in a farm-yard with abundance of food 

 and of litter, used with the double object of cleanliness and health, 

 is the best of all. The principal substances which contribute day 

 by day to increase the mass of our dunghills are straw, and the ex- 

 cretions and urine of horned cattle, horses, hogs, &c. These va- 

 rious substances, besides the organic elements which enter into their 

 composition, further contain the various mineral substances which 

 are indispensable to the development of vegetables. Animal excre- 

 ments of every kind, in fact, when they are burned, leave quantities 

 of ashes which are frequently very considerable, and in which are 

 encountered the same saline and earthy ingredients that pre-existed 

 in the forage with which the animals were supplied. Excrements, 

 therefore, necessarily vary in their composition according to the 

 kind of food that is consumed, and the nature and the state of health 

 of the animal which produced them. Those of the herbivora have 

 never been sufficiently examined. Thaer and Einhof have merely 

 ascertained that cow-dung contains an extractive principle, partly 

 coagulable by heat, and that remains of the food may be separated 

 from it. All excrementitious matters, in fact, contain a certain 

 quantity of the alimentary matter which has escaped digestion, 

 especially when animals are abundantly supplied with food. Some 

 albuminous matter is also found there ; but the substance after vege- 

 table remains that appears to predominate is bilious.* 



We know that after mastication, the food, mingled with saliva and 

 the secretions of the mucous glands, passes into the gullet, and from 

 thence into the stomach. There it imbibes gastric juice, turns sour, 

 becomes modified, and is finally converted into a kind of pulp which 

 is called chyme. Once formed, chyme passes into the small intes- 

 tines, where it encounters the bile and pacreatic juice, which modify 

 it, and cause it to separate into chyle, which is absorbed by the ves- 

 sels of the bowels, and excrementitious residue, which descends into 

 the large intestines, where it becomes a fetid mass that is expelled 

 from time to time by the animal. 



* The latest inquiries of the physiological chemists would lead us to suspect that 

 this was not the case. Bile ought only to be an occasional, and even an unnatural 

 constituent of animal excrement, if these views be well founded. It seems that the 

 elements of bile added to the elements of starch supply the precise elements of fat ,• a 

 BUbstnnce so abundantly formed in the process of digestion. The bile that is poured 

 Into the upper part of the uUiucnUry cauul is probjOiiy all usod up in forming Ikt— 

 Sack Ed. 



