4 ESSENTIALS OF CHEMICAL PHYSIOLOGY 



The compounds, or, as they are generally termed in physiology^ 

 the proxiviate principles, found in the body are divided into — 



(1) Mineral or inorganic compounds. 



(2) Organic compounds, or compounds of carbon. 



The inorganic compounds present are water, various acids (such 

 as hydrochloric acid in the gastric juice), ammonia (as in the urine), 

 and numerous salts, such as calcium phosphate in bone, sodium 

 chloride in blood and urine, and many others. 



The organic compounds are more numerous ; they may be sub- 

 divided into — 



1. Various groups of alcohols and organic acids, and their 

 derivatives, such as the fats and carbohydrates. 



2. Various derivatives of ammonia, amides, amines, urea, &c. 



3. Aromatic bodies, or derivatives of benzene. 



4. Proteids, the most important of all, and substances allied to 

 proteids like the albuminoids, pigments, and ferments. 



A more convenient practical method of grouping the proximate 

 principles of the body and of food is the following : — 



f Water. 



Inorganic .... J Salts — e.^. chlorides andphosphates of sodium 



( and calcium. 



( Proteids — e.g. albumin, myosin. 



Nitrogenous ^ ^^^^^^inoids—e.g. gelatin, keratin. 



° 1 Simpler nitrogenous bodies — e.g. lecithin. 



O B-an'c -^ icreatine, urea. 



* ^ ( Fats — e.g. butter, fats of adipose tissue. 



Non-nitrogenous Car6o%rfrai.s-e.^ sugar, starch 



° Simple orgamc bodies — e.g. alcoliol, cnoles- 



V terin, vegetable acids, and salts, lactic acid. 



Many of the substances enumerated above only occur in small 

 quantities. The most important are the inorganic substances, water 

 and salts ; and the organic substances, proteids, carbohydrates, and 

 fats. It is necessary in our subsequent study of the principles of 

 chemical physiology that we should always keep in mind this simple 

 classification ; the subdivision of organic substances into proteids, 

 fats, and carbohydrates forms the stai'ting point, the A B C, as one 

 might say, of chemical physiology. 



I will conclude this introductory chapter by giving a list of tlu> 

 apparatus and reagents necessary for a practical study of the subject, 

 and some tables which it will be often found convenient to refer to. 



The following set of reagents conveniently contained in 4 to 6 oz. glas& 

 stoppered bottles should be provided for each two students : — 

 Sulphuric acid, concentiatod. 

 „ ,, 'if) per cent. 



.. 01 „ 



