OFFICIAL PKEPARATIONS 77 



Aqua, pi. Aquce. — Waters are aqueous solutions of vola- 

 tile principles. They have no uniform strength and are 

 mostly solutions of volatile oils or gases. 



1 Mistura, pi. Misturce. — Mixtures are compounds consist- 

 ing of a combination of fluid preparations or compounds in 

 which solid substances are dissolved or held in suspension 

 by an appropriate vehicle. The term is thus very compre- 

 hensive, including most prescriptions for fluids used in 

 practice, but more narrowly it applies in pharmacy to insol- 

 uble materials suspended by suitable menstrua in water, the 

 whole to be shaken before used. They have no definite 

 strength. 



Emvlsum, pi. EmuLsa. — Emulsions are similar to mix- 

 tures in that an oily substance in a state of fine division is 

 held in suspension in a gummy or albuminous vehicle. 

 They have no uniform strength. 



8yrwpus, pi. Syrupi. — Sjrups are saccharine solutions. 

 The vehicle is usually water, although vinegar and alcohol 

 may be used, and they are all medicated except the simple 

 syrup. They are not of uniform strength. 



II. — Peepakations Whose Solvent is Alcohol. 



Tinctura, pi. Tindurce. — Tinctures are alcoholic solu- 

 tions of non-volatile principles, made usually by maceration 

 and percolation of the^ crude drug, They vary in strength ; 

 the more powerful contain 10 per cent., the weaker usually 

 20 per cent, of the crude drug. The alcohol in tinctures is 

 often an important factor in the action of the preparation. 

 Strong or diluted alcohol is used according to the solubility 

 of the active principle. 



Spiritus, pi. Spiritus. — Spirits are alcoholic solutions of 

 volatile substances, either gases, liquids or solids. They 

 have no uniform strength. 



Elixir, pi. Elixirs.— 'Eilixirs. are alcoholic solutions of 

 drugs containing sugar and aromatic substances. 



III.— Peepaeations Having Wine as a Solvent. 



Vinum. pi. rim.— Wines are weak tinctiiraa cnnta.ininc 



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