74 Detection of Adulterations. 



trated mucilage ; while, if castor oil be present, the mixture is opaque. 



Our authors prefer, however, the process of M. Planche. Mix 

 thoroughly one measure of ammonia, sp. gr. .915 with three meas- 

 ures of copaiva. If the copaiva be pure, the mixture will be trans- 

 parent ; while castor oil will produce an opacity proportionate to its 

 quantity. The test succeeds best between the temperatures of 50° 

 and 60° Fahrenheit. 



M. Ader gives the following process for obtaining the volatile oil 

 of copaiva, without distillation. Agitate strongly in a matrass, 100 

 parts of copaiva, and the same quantity of rectified alcohol ; then 

 add 37^ parts of a solution of caustic soda sp. gr. 1.373, and after 

 repeated agitation add 1 50 parts of water. In a few hours the volatile 

 oil is found on the surface of the solution. If the copaiva be pure, 

 and the process carefully conducted, about 44 per cent, of oil will be 



obtained. 



It is well known, that when pure copaiva is mixed widi one seven- 

 teenth of its weight of very pure magnesia, it becomes, on standing, 

 so solid that it may be formed into pills, possessing the medicinal 

 virtues of the liquid, without the unpleasant taste and odor, or the 

 irritating characters of the latter. Of several specimens which we 

 have obtained, but one has been pure enough for this purpose. 



Iodide of Potassium. — This substance, when in solution, is a hy- 

 driodate of potash ; and is commonly sold under that name. When 

 adulterated with substances having less action on the animal frame, 

 it will, of course, require a larger dose to produce a given effect, 

 than when pure. The consequence has been, that physicians who 

 have with safety employed large doses of an impure salt, and sub- 

 sequently used a pure preparation, have produced violent and unex- 

 pected effects, by giving the doses which they had been accustomed 

 to employ. The chloride of potassium, and common salt have been 

 discovered by M. Robiquet, as impurities in this iodide ; and the re- 

 semblance is so strong, that the fraud cannot be detected by the eye. 

 M. Robiquet has proposed the following processes for ascertaining 

 the existence and extent of the impurity. Dissolve equal quantities 

 of pure iodide and of that to be tested, in similar portions of water, 

 and introduce the solutions into retorts connected with receivers. 

 Add to each an excess of nitric acid, and boil to dryness. The 

 iodine will be liberated, and must be dried and weighed. Both spe- 

 cimens should yield the same quantity. We do not perceive the ne- 

 cessity of making this comparison, since it is known that 165 grains 



