ORGANIC ELEMENTS. 51 



6. Osmazome. This is the matiere extractive du bouillon, extractive, 

 and saponaceous extract of meat. When flesh, cut into small frag- 

 ments, is macerated in successive portions of cold water, the albumen, 

 osmazome, and salts are dissolved; and, on boiling the solution, the 

 albumen is coagulated. From the liquid remaining, the osmazome may 

 be procured in a separate state, by evaporating to the consistence of 

 an extract, and treating with cold alcohol. This substance is of a 

 reddish-brown colour; and is distinguished from the other animal prin- 

 ciples by solubility in water and alcohol whether cold or at the boil- 

 ing point and by not forming a jelly when its solution is concentrated 

 by evaporation. 



Osmazome exists in the muscles of animals, the blood, and the brain. 

 It gives the peculiar flavour of meat to soups ; and, according to Four- 

 croy, the brown crust of roast meat consists of it. 



Kreatin and Kreatinin are two principles which were formerly in- 

 cluded among the extractive or ill-defined matters of muscular tissue. 

 They have been investigated by Liebig, 1 who discovered them also in 

 urine. They appear to be like urea, mere products of the decomposition 

 of muscle. 



7. Mucus. This term has been applied to various substances; and 

 hence the discordant characters ascribed to it. Applying it to the fluid 

 secreted by mucous surfaces, it varies somewhat according to the source 

 whence it is derived. Its leading characters may be exemplified in that 

 derived from the nostrils, which has the following properties. It is 

 insoluble in alcohol and water, but imbibes a little of the latter, and 

 becomes transparent; it is neither coagulated by heat, nor rendered 

 horny; but is coagulated by tannic acid. 



Mucus, in a liquid state, serves as a protecting covering to different 

 parts. Hence it varies somewhat in its characters, according to the 

 office it has to fulfil. When inspissated, it forms, according to some, 

 the minute scales that are detached from the surface of the body by 

 friction, corns, and the thick layers of the soles of the feet, nails, and 

 horny parts; and it is contained in considerable quantity in hair, wool, 

 feathers, scales of fishes, &c. 



8. Urea.-* This proximate principle exists in the urine of the mam- 

 malia when they are in a state of health. In human urine it is less 

 abundant after a meal, and it may nearly disappear in diabetes, and 

 affections of the liver. It is obtained by evaporating urine to the con- 

 sistence of syrup. The syrup is then treated with four parts of alco- 

 hol, which are afterwards volatilized by heating the alcoholic extract. 

 The mass that remains is dissolved in water, or rather in alcohol, and 

 crystallized. 



The purest urea that has been obtained assumes the shape of acicu- 

 lar prisms similar to those of the muriate of strontian. It is colourless, 

 devoid of smell, or of action on blue vegetable colours, transparent, and 

 somewhat hard. Its taste is cool, slightly sharp, and its specific gra- 

 vity is greater than that of water. 



Urea is supposed by Dr. Prout to be chiefly derived from the de- 



1 Chemistry of Food, London, 1847. 



