332 SCIENCE OF AGRICULTURE. Part II. 



ingenious researches of Hatchett. The theory of their operation is similar to that of 

 bone and horn shavings. 



2187. The refuse of the different manufactures of skin and leather forra very useful 

 manures ; such as the shavings of the currier, furriers' clippings, and the offals of the 

 tan-yard and of the glue-maker. The gelatine contained in every kind of skin is in a 

 state fitted for its gradual solution or decomposition ; and when buried in the soil, it 

 lasts for a considerable time, and constantly affords a supply of nutritive matter to the 

 plants in its neighborhood. 



2188. Blood contains certain quantities of all the principles found in other animal sub- 

 stances, and is consequently a very good manure. It has been already stated that it 

 contains fibrine ; it likevi^ise contains albumen ; the red particles in it, which hare been 

 supposed by many foreign chemists to be coloured by iron in a particular state of combin- 

 ation with oxygen and acid matter, Brande considers as formed of a peculiar animal 

 substance containing very little iron. The scum taken from the boilers of the sugar- 

 |)akers, and which is used as manure, principally consists of bullocks' blood, which has 

 been employed for the purpose of separating the impurities of common brown sugar, by 

 means of the coagulation of its albuminous matter by the heat of the boiler. 



2189. The different species of corals, corallines, and sponges, must be considered as sub- 

 stances of animal origin. From the analysis of Hatchett, it appears that all these 

 substances contain considerable quantities of a matter analogous to coagulated albumen ; 

 the sponges afford likewise gelatine. According to Merat Guillot, white coral contains 

 equal parts of animal matter and carbonate of lime; red coral 46*5 of animal matter, 

 and 53*5 of carbonate of lime; articulated coralline 51 of animal matter, and 49 of 

 carbonate of lime. These substances are never used as manure in this country, except 

 in cases when they are accidentally mixed with sea-weed ; but it is probable that the 

 corallines might be advantageously employed, as they are found in considerable quantity 

 on the rocks, and bottoms of the rocky pools on many parts of our coast, where the land 

 gradually declines towards the sea ; and they might be detached by hoes, and collected 

 without much trouble. 



2190. x\mongst excrementitious animal substances used as manures, urine is the one 

 upon which the greatest number of chemical experiments have been made, and the 

 nature of which is best understood. The urine of the cow contains, according to the 

 experiments of Brande : water 65 ; phosphate of lime 3 ; muriates of potassa and ammonia 

 15 ; sulphate of potassa 6 ; carbonates, potassa, and ammonia 4 ; urea 4. 



2191. The urine of the horse, according to Fourcroy and Vauquelin, contains, of car- 

 bonate of lime 1 1, carbonate of soda 9, benzoate of soda 24, muriate of potassa 9, urea 7, 

 water and mucilage 940. In addition to these substances, Brande found in it phosphate 

 of lime. The urine of the ass, the camel, the rabbit, and domestic fowls, have been 

 submitted to different experiments, and their constitution have been found similar. In 

 the urine of the rabbit, in addition to most of the ingredients above mentioned, Vau- 

 quelin detected gelatine ; and the same chemist discovered uric acid in the urine of do- 

 mestic fowls. Human urine contains a greater variety of constituents than any other 

 species examined. Urea, uric acid, and another acid similar to it in nature, called 

 rosacic acid, acetic acid, albumen, gelatine, a resinous matter, and various salts are found 

 in it. The human urine differs in composition, according to the state of the body, and 

 the nature of the food and drink made use of. In many cases of disease there is a much 

 larger quantity of gelatine and albumen than usual in the urine j and in diabetes it con- 

 tains sugar. It is probable that the urine of the same animal must likewise differ 

 according to the different nature of the food and drink used; and this will account for 

 discordances in some of the analysis that have been published on the subject Urine is 

 very liable to change, and to undergo the putrefactive process ; and that of carnivorous 

 animals more rapidly than that of graminivorous animals. In proportion as there is more 

 gelatine or albumen in urine, so in proportion does it putrefy more quickly The species 

 of urine that contains most albumen, gelatine, and urea, are the best as manures ; and all 

 urine contains the essential elements of vegetables in a state of solution. During the 

 putrefaction of urine the greatest part of the soluble animal matter that it contains is 

 destroyed: it should consequently be used as fresh as possible; but if not mixed with 

 solid matter, it should be diluted with water, as, when pure, it contains too large a quan- 

 tity of animal matter to form a proper fluid nourishment for absorption by the roots of 

 plants. 



2192. Pwirirf wnrae abounds in ammoniacal salts; and though less active than fresh 

 urine, is a very powerful manure. According to a recent analysis published by Berze- 

 lius, 1000 parts of urine are composed of, water 933 ; urea 30*1 ; uric acid 1 ; muriate of 

 ammonia, free lactic acid, lactate of ammonia, and animal matter 17-14. Tlie remainder 

 different salts, phosphates, sulphates, and muriates. 



2193. Dung of birds. Amongst excrementitious solid substances used as manures, one 

 of the mo6t powerful is the dung of birds that feed on animal food, particularly the dung of 



