20 ALBUMEN. 



Coloring matters. Coloring matter, as obtained, exists in two states : it is, first, a pre- 

 existing substance of a particular vegetable; and, secondly, it is one which is formed by 

 the chemical action of another substance upon a given vegetable product. Madder is an 

 instance of the former ; and perhaps indigo, of the latter. This substance, it is true, 

 preexists in the leaf of the Indigqfera in a white condition, and so remains until the leaf 

 begins to decay, when the white indigo absorbs oxygen from the atmosphere, which is 

 known by the appearance of many blue points in the texture of the decaying leaf. 



ALBUMEN, FIBRIN, CASEIN. 



It is not my purpose to eulogize the age, or the men of the age ; still it is a just tribute 

 to science, and to men devoted to science, to say that the discovery that the three organic 

 productions under consideration are indentical in composition, is really one of the greatest 

 in modern times, especially when coupled with the fact that they are also identical with 

 bodies of the same name derived from the animal kingdom. Vegetable albumen is the 

 same as animal albumen, in composition. This discovery points out the source of these 

 important bodies, and establishes clearly the offices delegated to the vegetable kingdom, 

 namely, the elaboration of the fit elements of food, or nutrient matters, leaving the 

 formative functions only to the animal ; the power of shaping or moulding them, to the 

 necessities imposed by nature. The animal consumes or eats what is essentially his own 

 flesh, which is duly prepared in the grass of the fields. This subordination of the vegeta- 

 ble to the animal kingdom, is the greatest proof of design : it supports fully the doctiine 

 maintained by Paley. 



Albumen. The animal and vegetable fluids abound in this substance. In the white of 

 the egg, and indeed in all eggs and in all animals, it exists in its greatest purity. With- 

 out undergoing chemical changes, albumen may be said to exist in two states ; one soluble, 

 and the other insoluble. The first state is the natural one : it passes into the other at the 

 temperature of 167° Fahr. If albumen is carefully dried at a temperature not exceeding 

 120°, it still retains its solubility, and may even be exposed, when thus dried, to a tem- 

 perature of 212° without losing its solubility. When it is exposed to a temperature of 

 167°, it coagulates, and then becomes nearly insoluble. Acids also possess the power of 

 coagulating it, except the acetic, tartaric and phosphoric acids, in each of which it is per- 

 fectly soluble. So also the alkalies and their carbonates form soluble compounds with 

 albumen. 



Albumen is usually detected in fluids by the application of heat. The addition of 

 nitric acid also coagulates the albumen. 



The four organic elements, carbon, hydrogen, nitrogen and oxygen, together with 

 sulphur and phosphorus, constitute this body. The proportions which are given are 

 C 4 oo+H 3 , -fN 50 -fO,,o+SP. 



The albumen of the blood differs from that of eggs, in containing one atom more of 



