290 SCIENCE OF AGRICULTURE. Taut II. 



brought into union in the animal system by die agency <>f the vital principle, their state 

 <>i' combination may be expected to differ widely from the ordinary results of electric 

 attraction. When Buch compounds of organisation are submitted to analysis, the influ- 

 ence of the vital principle having ceased, the products obtained may be regarded, in 

 manj cases, a-, modifications of the elements of the substance, occasioned by the pro- 

 cesses employed, rather than the display of the number or nature of the ingredients, as 

 tiny existed previously to the analytical operations. Hence the great caution requisite 

 in drawing conclusions regarding the composition of animal bodies. 



1917. The elementary substances which ore considered us entering into the pens nfani- 

 tnalt are, carbon, hydrogen, oxygen, azote, phosphorus, sulphur, fluoric acid, muriatic 

 acid, iodine, potash, soda, ammonia, lime, magnesia, silica, iron, and manganese. 



1918. Carbon exists in various states of combination in the fluids, as well as in the solids, of every 

 animal ; and Das been detected in the form of charcoal in the lungs. When animal substances are exposed 

 to a high temperature in closed vesseU, the charcoal which is produced differs considerably from that 

 which is obtained by the same means from vegetables. It is more glossy in appearance, and is incinerated 

 with much greater difficulty. 



1919. Hydrogen is univeri illy distributed in the animal kingdom ; it occurs as a constituent ingredient 

 of all the fluids, and of many of the solids. It is invariably in a state of combination with charcoal ; for, 

 u fir as we know, it has never been detected in an uncombined or separate state. It has been found in 

 tlu' human intestines, in the form of carburetted hydrogen. 



1920. Oxyg a is as widely distributed as the preceding, in the fluids and solids of all animals. A constant 

 supply Of it from the atmosphere is indispensably necessary to the continuation of animal life. It occurs, 

 not only in combination with other bodies, but probably, likewise in a separate state, in the air-bag of 

 fishes, iii which it is found, varying in quantity, according to the species, and the depth at which the 

 fishes have been caught. It i> common, m union with charcoal, forming carbonic acid. 



1921. Azotic gas is very widely distributed as a component part of animal substances. It occurs in 

 almost all the fluids, and in those solid parts which have carbon as a base. The almost universal pre- 

 valence of this principle in animal substances constitutes one of the most certain marks by which they 

 may be distinguished from vegetables. Azote likewise occurs, in an uncombined state, in the air-bag of 

 gome lishes. 



1922. Phosphorus. This inflammable body exists, in union with oxygen, in the state of phosphoric 

 acid, in many of the solids and fluids of animals. Its existence, however, in an uncombined state, has 

 not been satisfactorily determined, although there appears a tendency to refer the lumirousness of several 

 animals to the slow combustion of this substance. Even phosphoric acid can scarcely bt said to exist in 

 a separate state, being found in combination with potash, soda, ammonia, lime, or magnesia. 



1923. Sul/>/tnr, in combination, exists in considerable abundance in animal substances It can scarcely 

 be said to occur in a separate state in animals ; at least, the experiments which may he quoted as 

 encouraging such a supposition are by no means decisive. United with oxygen, in the form of sulphuric 

 acid, it exists in combination with potash, soda, and lime. 



1924. Fluoric acid has been detected in bones and urine, in a state of combination with lime. 



1925. Muriatic acid exists in a great number of the animal fluids, in combination with an alkali, as in 

 the ammonia and soda of urine. 



1926. Iodine has been detected in sponge. 



1927. Potash exists in combination with the sulphuric, muriatic, or phosphoric acids ; but it is far from 

 abundant in animal fluids. 



1928. Soda is present in all the fluids in various states of combination, and is more abundant than the 

 preceding It gives to many of the secretions the alkaline property of changing vegetable blues into 

 green. It is found in union with the carbonic, phosphoric, sulphuric, and muriatic acids. 



1929. Ammonia exists in its elements in all the fluids, and many of the solids, of animals, and is fre- 

 quently produced during putrefaction These elements are likewise found united in the system, and the 

 alkali then appears in union with the various acids, as the phosphoric, muriatic, and lactic. 



19'!0. Lime, of which the hard parts of animals, such as bones and shells, are principally composed, is of 

 universal occurrence. It is always in a state of combination, and chiefly with the carbonic or phosphoiic 

 acids. 



1931. Magnesia occurs sparingly. It has been detected in the bones, blood, and some other substances, 

 but always in small quantity, and chiefly in union with phosphoric acid. 



19 ;2 Silica occurs more sparingly than the preceding. It is found in the hair, urine, and urinary 

 calculi. 



193.). Iron has hitherto only been detected in the colouring matter of the blood, in bile, and in milk. 

 Its peculiar state of combination in the blood has given rise to various conjectures; but a satisfactory 

 solution of the question has not yet been obtained. In milk, it appears to be in the state of phosphate. 



l!> 14. Manganese, in oxide, has been observed, along with iron, in the ashes of hair. 



1935. Such are the simple substances which have been detected by chemists in the 

 solids and fluids of animals ; but seldom in a free state, and often in such various 

 proportions of combination to render it extremely difficult to determine their true 

 condition. 



1936. The compounds of organisation are gelatine, albumen, fibrin, mucus, urea, sugar, 

 oils, and acids. 



1937. Gelatine occurs in nearly a pure state in the air-bags of different kinds of fishes, as, for example, 

 isinglass, which, if dissolved in hot water anil allowed to cool, forms jelly. When a solution of tannin is 

 dropped into a solution of gelatine, a union takes place, and an insoluble precipitate of a whitish colour 

 falls to the bottom. It is on the union of the tannin of the oak bark with the gelatine of the hides, that the 

 process of tanning leather depends. Gelatine exists in abundance in different parts of animals, as bones, 

 muscles, skin, ligaments, membranes, and blood. It is obtained from these substances by boiling them 

 in warm water; removing the impurities, by skimming, as they rise to the surface, or by .subsequent 

 straining and clarifying. It is then boiled to a proper consistence. It is the characteristic ingredient of 

 the softest and most flexible parts of animals. 



i" 18. Gelatine is extensively used in the «/7s, under the names of glue and size, on account of its adhesive 

 quality, and to give the requisite stiffness to certain articles of manufacture In domestic economy, it is 

 likewise employed in the form of jelly, and in the formation of various kinds of soup. What is termed 

 Portable Soup is merely jelly which has been dried, having been previously seasoned, according to the 

 taste, with different spices. 



1939. Albumen, the white of an egg, exists in great abundance, both in a coagulated 

 and liquid state, in the different parts of animals. Hair, nails, and horn are composed 



