INTRODUCTION. 3 



sion of a certain country. (U. S. P. is revised every 

 ten years.) 



A Dispensatory is a commentary upon one or 

 more of the national pharmacopoeias, treating in de- 

 tail of the medicinal substances official * therein as 

 well as of such unofficial f ones as are of especial in- 

 terest and in general use. 



Official Preparations. 



Alkaloids are active, nitrogenous principles ex- 

 isting in plants, from which they are extracted by 

 chemical art. They are organic bases, forming salts 

 with acids, and contain N with C and H. Alkaloids 

 are alkaline in reaction, insoluble or but sparingly 

 soluble in water, more readily soluble in alcohol, and 

 their salts are more soluble in water than in any other 

 liquid. In a general way they are very suitable for 

 hypodermic medication. 



Aqu^, waters, aqueous solutions of volatile sub- 

 stances (which may be solids, liquids, or gases). 

 They are dissolved in four ways : 



First, by solution in hot or cold water. 



Second, by filtration through an absorbent powder. 



Third, by percolation through cotton saturated with 

 the substance. 



Fourth, by distillation. 



Cerata, cerates, are unctuous preparations similar 



* Official — according to law. 



f Officinal (officina, an office)— so customary and well 

 known as to be found in all shops or offices. 



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