CASKINK, GELATINE, ETC.] 



CHEMISTRY. 



423 



constituent of blood, from which it may he removed hy 

 be;iti:;g up that licjuid with twigs, to which the febrine 

 a'ih-res In a solid state it exists in flesh, in the gluten 

 of flour, and in grasses. The chemical composition of 

 tibriue is 



Carbon 627 



Hydrogen . . . . 69 



Nitrogen .... 1-V4 

 Oxygen . . . . 23 -5 

 Phosphorus .... 

 Sulphur .... 1-2 



1000 



From this we observe, that it scarcely differs from 

 albumen, and in many of its characteristics it resembles 

 that substance. 



CASKIXE is found in milk ; and, in fact, cheese is nearly 

 pure caseine. A vegetable substance, legumine, much 

 ri-.-'i-mblc-s caseine, and is found in cabbage and other 

 plants. Pure caseine is insoluble in water and alcohol, 

 but readily dissolves in alkaline solutions. In making 

 cli.'i-se, the caseine is coagulated by means of an acid, 

 obtained from the stomach of the calf. This is called 

 rennet, and hydrochloric acid may be substituted for it, 

 having, to some extent, a like effect. Caseine contains 

 ii, hydrogen, nitrogen, oxygen, and sulphur. 



GELATINE and CHONDKINE contain the same elemen- 

 tary bodies. They are easily extracted from tissues, 

 bone*, <tc., by means of hot water ; and calf's-foot jelly 

 is an instance of the former substance ; whilst isinglass, 

 glue, and size, represent it in a more solid state. In 

 manufacturing bone manure, much chondrine IB often 

 produced. This substance differs from gelatine in not 

 as-siiming what is generally termed a gelatinous state, 

 and is not precipitable by tannic acid, which precipitates 

 gelatine readily. 



PROTEINS is obtainable from albumen, fibrine, etc., 

 through their decomposition by an alkali, and subsequent 

 precipitation by acetic acid. It seems to be a proximate 

 principle of albumen, fibrine, and caseine. 



KREATINK is a principle existing in flesh, from which 

 it may be extracted by aqueous infusion. It is composed 

 of carbon, hydrogen, oxygen, and nitrogen. It is soluble 

 in hot water, and U extracted from heat in the process 

 of stewing, SO. 



BLOOD. This liquid is essential to animal existence, 

 and consists of water and organic matter. Its specific 

 gravity varies, but may he stated at 1 05, water * UK). 

 The red particles, which owe their colour to lurmatosine, 

 are the heaviest portion of the liquid. The blood cor- 

 puscles vary in size in different animals ; and lately M. 

 Duboscq, of Paris, has rendered great service to phy- 

 siology by the photographs he has produced of these 

 globules. Their general appearance is accordingly charac- 

 teristic of their origin. The following cuts will illustrate 

 the fact : Fig. 5 representing the blood globules of 

 man ; Fig. 86, those of fishes. 



fig. M. tig. 86. 



J 



We need scarcely state, that by means of the blood 

 every part of the body is nourished ; hence it must con- 

 tain every substance required in the animal from which 

 it has been obtained for analysis. The following gives 

 the proportions of proximate principles in human blood 

 in a thousand parts : 



Male. Female. 



Water 7790 791 '0 



Red particles . . . . 1410 127 -0 



Albumen 6!)-4 705 



Earthy salts, <tc. . . . 68 7 4 



F;itty particles ... 16 ] -6 



The above proportions differ from those given by other 



authors ; but we need scarcely state that the composition 

 of the blood incessantly varies in the same individual, 

 owing to change of diet, disease, and other causes. 



Ons AND FATS. At a previous page we have drawn 

 attention to the oily matters produced by vegetables. 

 To these the animal fats present much resemblance. 

 Generally speaking, fat may be resolved by the action of 

 alkalies and acids into oleine, atearine, margarine, and 

 glycerine, each of which afford acids, theoleic, stearic, &c. ; 

 and such unite with alkalies and other bases. Thus soap 

 is a stearate of soda ; and by the addition to it of a dilute 

 acid, the stearic acid is set free. Stearine is thus manu- 

 factured for making candles. The fat is made into ;m 

 earth-soap by means of lim ; to this dilute sulphuric 

 acid is added, which sets the stearine, orsteario acid, free. 

 By pressure and purification, it is eventually presented 

 in a solid form. Margarine, oleine, and glycerine are 

 simultaneously produced by the above process. 



Spermaceti is a solid obtained from a species of whale, 

 and is analogous to stearine in most of its characters. 

 Butter is an animal fat, obtained from the milk of tho 

 female. 



Amongst the secretions, such as bile, milk, urine, <fcc., 

 we need only single out urea, which is a constituent of 

 urine, and is interesting, as it may be produced artificially. 

 For this purpose cyanate of potash is dissolved, together 

 with sulphate of ammonia. The solution is evaporated 

 to dryness ; and the urea so formed, is extracted by 

 means of alcohol. From this solution crystallised urea 

 may be obtained, affording a rare instance of an animal 

 product being imitable by the direct combination of 

 ite elements, apart from vital action. Its composition 

 is C ? H 4 Nj O ? . Uric acid is a component of urine, 

 and is afforded in a solid state in guano, and the urine 

 of serpents. Hippuric acid exists in the uriue of gram- 

 nivorous animals. 



BONES. The framework or bones of animals consists 

 of earthy matter, united by means of organic substances. 

 The composition of bone varies, not only in different 

 animals, but in the sexes of each. The following table 

 affords an analysis of human bones : 



Animal matter 33'PO 



Phosphate of lime and fluoride of calcium 53 '04 



Carbonate of lime 11-30 



Phosphate of magnesia 1-16 



Soda and common salt ...... 1 '20 



100-00 



In the Crustacea, and marine animals generally, the 

 carbonate of lime chiefly abounds ; and thus the shells of 

 mollusca are readily dissolved away, and engraved on, by 

 means of hydrochloric acid. 



Skin, nails, and horns may be considered as nearly 

 identical in their constitution and production ; the same 

 may be remarked of hair and wool. In hair, both man- 

 ganese and sulphur have been found. 



Into the philosophy of nutrition, the production of 

 bone, flesh, muscle, nerve, the secretions, <tc., we cannot 

 enter, as such will be fully considered in the section on 

 Comparative Physiokiyy, at the commencement of Vol. 

 II. Our design has been to simply refer to those parts 

 of the animal, tho coiisMeration of which is confined to 

 the chemical details, and not to trench on subjects on 

 which our space and arrangement forbid us to enlarge. 



We may, however, add a few remarks on the manufac- 

 tures connected with animal chemistry. Of late years, 

 much attention has been paid to the production of animal 

 manures. The bone, after being calcined, is drenched 

 with dilute sulphuric acid, by which a superphosphate of 

 lime is produced, which is of great value to the farmer. 

 Blood, and other animal waste, have similarly been ap- 

 plied ; and scarcely any substance of an animal nature 

 exists, that is not now used for the purpose. 



Hoofs, horns, blood, <fec. , are used in the manufacture 

 of prussiate of potass, and in the process of cementation. 

 Skins are, as is well known, converted into leather, by 

 the process of tanning, in which the tannic acid* converts 

 the soluble into insoluble substances. 



8w ante, p. 113. 



