52 INTRODUCTION. 



1. Protein, 6. Globulin, 



2. Albumen, 7. Spermatin, 



3. Fibrin, 8. Mucus, 



4. Casein, 9. Lachrymal matter, 41 



5. Pepsin, 10. Keratin. 



Protein is regarded as the basis of all the other elements, 

 is found in every animal, and it is said that no tissue or 

 organ is destitute of its presence. 



It can be obtained by boiling albumen in a weak so- 

 lution of caustic potass, and then precipitating with an 

 acid. 



The gluten of wheat-flour, after the starch is washed 

 away, and treated in the same manner, also yields protein. 



Thus obtained, in the moist state it is gelatinous, without 

 smell or taste, insoluble in water, ether or alcohol, but 

 soluble in dilute acid. When dry, it is hard, brown, and 

 brittle. 



According to Mulder, its discoverer, it is chemically 

 composed in atomic weights, of carbon 40, hydrogen 31, 

 nitrogen 5, oxygen 12. 



Albumen is found in the serum of the blood, lymph, chyle, 

 &nd a beautiful specimen is seen in the white of the egg. 

 It is one of the special elements of the brain, and exists 

 also in pus, and many of the secretions. 



It is yellow and .brittle when dry, coagulates by heat, 

 creosote, spirits of wine, and some acids; is soluble in 

 water, and forms an insoluble compound with corrosive 

 sublimate, sugar of lead, alum, nitric and tannic acids. 



It is composed, according to Gay Lussac and Thenard, of 



Nitrogen, 15.705, 



Carbon, 52.883, 

 Hydrogen, *7.540, 



Oxygen, 23.8*72, in an hundred parts. 



Fibrine constitutes the basis of the muscular system, 

 exists in the blood, chyle, lymph, and in abundance upon 



