a way as to throw each other out of solution, causing 

 precipitates or a disagreeable looking or tasting 

 mixture. 



The incompatibility of drrgs is governed in the 

 majority of cases by a few simple rules which we will 

 give below. 



1st. In mixing any salt with strong acids, decom- 

 position is very apt to take pace. 



2nd. Alkalies should never be mixed with- salts of 

 the metals proper. Decomposition takes place, and 

 Iheir bases are precipitated. 



3d. Vegetable astringents precipitate albumen, 

 gelatine, vegetable alkalies, and numerous metallic 

 oxides, and with ^alts of iron prod ce inky : olutions. 



4th. Glucosides should not be mixed with free 

 acids. 



5th. Double decomposition will notoccur between 

 solutions of two salts, unl ss, by the interchange of 

 the two baselous radicals a substance will be p o- 

 duced which is either insoluble o volatile. 



6,h. When a solu ion of a compound is brought 

 in contact with a solution ot another compound, 

 and by an interchange of radica's, an insoluble com- 

 pound will be rendered pOSSible that compound 

 Will be precipitated. 



Below we give a list of the volatiles, and soluble 

 and insoluble salts. When these are thoroughly 

 learned one can readily see where double decompo- 

 sition will occur. 



VolatHeS. The volatile substances are H 2 O 

 CO 2 H 2 S Hey HI HBr HCL HNO, NH 3 

 and HNO 3 . 



Insoluble SaltS. All Hydrates, Carbonates, 

 Phosphates, Oxides, Sulphides, Arsenates, Arsenites, 

 Borates Tanates and Silicates, except those of 

 Sodium, Potassium and Ammonium, are insoluble. 



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