396 THE HUMAN BODY 



much the part of wisdom as in the use of alcohol. Again, like 

 alcohol, they are best left alone during early life. 



The improper preparation of tea and coffee, by boiling them in 

 water, carries into solution, in addition to the stimulating prin- 

 ciple, a substance, tannin, whose effect upon the system is apt to be 

 distinctly harmful. These beverages should therefore always be 

 prepared by methods which do not involve prolonged or even 

 brief boiling while the tea leaves or coffee grounds are actually 

 present in the liquid. 



