with iodides, bromides, and chlorates; ammonium salts and hydrates and 

 carbonates of the alkalies. 



(b) Resulting in the freeing of a liquid body, chloral and butylchloral 

 with alkalies (chloroform freed). 



(c) Resulting in the freeing of dextrose or other sugar, glucosides with 

 acids and alkalies. 



(d) Resulting in liberation of so much gas suddenly as to cause an ex- 

 plosion. Chromic acid, concentrated nitric acid, nitrates, permanganates, 

 chlorates, with such substances as sulphur and sulphides, sulphites, io- 

 dides, phosphorus, hypophosphites, reduced iron, and many organic bodies, 

 sugar, tannin, etc. These reactions only occur when the dry substances 

 are triturated together or in some cases when mixed in very concentrated 

 solutions. 



5. In some cases when two solids are triturated together a soft sticky 

 or a damp mass, or a liquid is formed: the reaction is probably always to a 

 certain extent chemical. Such substances are camphor, carbolic acid, 

 thymol, phenozone, phenacetin, chloral, sodium phosphate, lead acetate. 

 Details will be found under the various drugs. 



PHARMACEUTICAL OR PHYSICAL INCOMPATIBILITY. 



1. Resulting in precipitation of one of the ingredients in solution owing 

 to its decreased solubility when its solvent is diluted by another liquid; 

 The dilution of aqueous solutions of acacia, proteins, salts (if strong), 

 and emulsions with alcohol. Some gums as well as starches and dextrins 

 are similarly precipitated by alcohol. In some of the cases that will occur 

 under this rule the precipitate is not an important constituent, for ex- 

 ample, the Liquid Extract of Cascara Sagrada gives a precipitate with 

 alcohol, the precipitate consists however of unimportant constituents and 

 may be filtered off. The dilution of alcoholic solutions of resins, oleo- 

 resins, oils, etc., by water. In some of these cases also the precipitate is 

 unimportant, for example, Liquid Extract of Nux Vomica and water. 



It must be distinctly understood that at times it is advisable or even 

 necessary to order incompatibles in a prescription. Attention might be 

 called to the fact that the Pharmacopoeia contains such formulae, for ex- 

 ample the Lotio Hydryrgyri Nigra, and the Mistura Ferri Composita. 

 Whenever the physician orders such a preparation he should warn the 

 patient that the bottle will contain a deposit. It is only rarely that one 

 should write such a prescription as will involve an uncorrected incom- 

 patibility. No prescription should ever be written which if dispensed 

 would lead to the precipitation of any highly active ingredient, as in the 

 cases of such a precipitate the patient might readily be poisoned by getting 

 an over-dose of the potent precipitate in the last dose. The practitioner 



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