BOTANY. 



Mucilage is a variety of gum, but has less attraction 

 for water. 



Resin. 



Resin is insoluble in water, but very soluble in 

 alcohol. 



Tar and pitch consist principally of resin in a par- 

 tially decomposed state. Tar is made by the com- 

 bustion of the fir-tree, and pitch by the evaporation 

 of the more volatile parts of the tar. 



Gluten. 



Gluten may be obtained from wheat-flour by the 

 following process : The flour is to be made into a 

 paste, which, after being carefully washed by knead- 

 ing under a small stream of water, until this fluid has 

 carried away all the starch, what remains is the glu- 

 ten, which is a tenacious, ductile, elastic substance, 

 without taste. It is very slightly soluble. in cold 

 water, and is subject to the caseous fermentation. 

 It appears to be an extremely nutritive substance, 

 and wheat seems indebted for its superiority to the 

 large quantity of gluten it contains. 



Indigo. 



Indigo is not soluble in water, and but slightly in 

 alcohol. Its true solvent is sulphuric acid. Mr. 

 Dalton considers the value of indigo to be in propor- 

 tion to the quantity of real oxymuriate of lime neces- 

 sary to destroy its colour, and that a tolerable esti- 

 mate of its value may be made from the quantity and 

 intensity of the amber -coloured liquid produced by 

 the indigo during the process. 



Albumen. 



Albumen, in its pure form, is a thick, glairy, taste- 

 less fluid, precisely the same as the white of an egg. 



