OFFICIAL PREPARATIONS 75 



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

 tile principles. They have no uniform strength and are 

 mostly solutions of volatile oils or gases. 



Mistura, pi. 3IisturcB. — 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. 



JSmnlsum, pi. Eraulsa. — 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. 



Syrupus, pi. Syrupi — Syrups 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. — Preparations Whose Solvent is Alcohol. 



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

 tions of non-volatile principles, made usually by maceration 

 and percolation of the crude drug. They vary in strength, 

 usually from 5 to 20 per cent., but even exceed these limits. 

 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. — Elixirs are alcoholic solutions of 

 drugs containing sugar and aromatic substances. 



III. — Preparations Having Wine as a Solvent. 



Vinum, pi. Vina. — Wines are weak tinctures containing 



