38 SYNOPSIS OF VETERINARY 



Chemical. — Reaction between drugs, resulting in new com- 

 pounds. 



Physiological. — When a drug opposes the action of another. 



Pharmaceutical. — When an unsightly mixture results. 



i. Stimulants are antagonized by sedatives, alkalies by 

 acids, and vice versa. 



2. Never combine free acids with carbonates or hydrates. 



3. Strong acids displace weaker ones, and should always be 

 used alone. 



Two or more soluble salts should in general not be 

 combined, they may form new compounds with different prop- 

 erties. 



4. Alkalies neutralize free acids, they displace weak or vola- 

 tile bases of salts in solution. 



5. Oxides of alkalies decompose the metallic salts, also alka- 

 line salts. 



6. Alkaloids in solution are precipitated by alkalies, by alka- 

 line salts, by salts that produce insoluble compounds, by tannic 

 acid, by gallic acid and vegetable substances containing them. 



Remember that because a mixture is clear, it does not follow 

 that no incompatibility or reaction has taken place ; as substances 

 in solution may be displaced without precipitation, the new pro- 

 duct may be soluble in the solution. 



7. Corrosive Sublimate and Potassium Iodide should be pre- 

 scribed alone ; Acetate of Lead, Subacetate of Lead and Nitrate of 

 Silver also, except the latter may be combined with Opium. 



It is best to prescribe the following alone except when the 

 result of the combination is definitely known; Sulphuric Acid, 

 Hydrochloric Acid, Hydrocyanic Acid, Tannic Acid, lime-water, 

 Tr. ferri. chloride, Syr. Iod. of Iron, Citrate of Iron and Quinine, 

 Tr. Guaiac, Salts of Morphine, except with the alkaloids, Fowler's 

 solution, and Acetate of Zinc. 



8. Never order a drug in combination with any of its tests 

 or antidotes. 



9. Never mix mineral acids with alcohol, they form ethers 

 similar to chloroform. 



10. Alcohol or water added to a tincture or fluid extract 

 will throw it out of solution, but not necessarily prevent the 

 physiological action. 



