ALBUMIN-LIKE MATTERS. 863 



or of protection. To their presence is due the fragrance of many 

 fruits and flowers, notably those of orange, bergainot, and the 

 mints. Associated with the ethereal oils, the camphors occupy a 

 prominent place. They are generally regarded as the products 

 of the slight oxidation of some ethereal oils, The following is 

 the best known, C 10 H 16 O (Laurel-camphor). 



956. Products free from nitrogen. VII. Resins and Balsams. 

 These substances, which differ much in consistence, color, and 

 other physical properties, contain comparatively little oxygen, 

 are mostly amorphous, insoluble in water, and sometimes pos- 

 sess a slight acid reaction. 



Balsams are defined as " mixtures of resins with volatile oils, 

 the resins being produced from the oils by oxidation, so that a 

 balsam ma} 7 be regarded as an intermediate product between 

 a volatile oil and a perfect resin." l 



The Balsams are generally divided into two groups : (1) those 

 containing much cinnamic acid, as Balsam of Tolu, Peru, etc. ; 

 and (2) those which are purely oleo-resinous, as Balsam Copaiba, 

 Fir, etc. 2 



Certain resins and caoutchouc-like matters are found in large 

 amount in the latex. 



957. Products containing nitrogen. I. The albumin-like mat- 

 ters. Ritthausen classifies these substances into (1) Albumin of 

 plants ; (2) Casein of plants ; (3) Gelatin of plants. 



Albumin of plants is the term applied to the protein mat- 

 ters which readily coagulate from their aqueous solutions upon 

 the action of heat or acids. The coagula dissolve more or less 

 readily in potassic hydrate, exhibiting considerable differences 

 in respect to solubility. They contain from 2.6 to 4.6 per cent 

 of ash, and have the following elementary composition : 



Carbon 52.31-54.33 per cent. 



Hydrogen 7.13- 7.73 " 



Nitrogen 15.49-17.60 " 



Sulphur 76- 1.55 " 



Oxygen 20.55-22.98 " 



Casein of plants comprises the following substances : legu- 

 min, gluten-casein, conglutin. Solutions of these are precipi- 

 tated by dilute acids and by rennet. The precipitates are readily 



1 Watts : Dictionary of Chemistry, i., 1863, p. 491. 



2 A solution of the coloring-matter of alkanet root in dilute alcohol applied 

 to a thin section of a plant containing resins colors the resins red after a few 

 minutes, but does not serve to distinguish one from another. 



