112 Mr. R. Phillips on the Means of ascertaining 



Having repeatedly of late been requested to examine va- 

 rious samples of sulphate of quina, I thought it might be use- 

 ful to state the several modes which may be employed for that 

 purpose: and I make the present communication with the 

 greater confidence, because I have received the very able as- 

 sistance of my friend Mr. John T. Barry, of Lombard-street, to 

 whose chemical skill, and the opportunity of frequently apply- 

 ing it, I am indebted for the greater number of hints and facts 

 detailed in this paper. 



Pure sulphate of quina has the form of minute fibrous cry- 

 stals, it is inodorous, and its taste is bitter. If certain vegeta- 

 ble products, such as starch or sugar, be mechanically mixed 

 with it, they may possibly be observed by merely inspecting 

 the preparation with a glass. 



1st. If the sulphate of quina be mixed with a considerable 

 proportion of foreign matter, it may probably be detected by 

 dissolving the salt in question in about three hundred times 

 its weight of water, — say one grain in about five fluid drams 

 of boiling distilled water. On cooling, pure sulphate of quina 

 will be deposited in feathery crystals in twenty-four hours, if 

 there be no adulteration. 



2dly. As indirect, but as good collateral evidence, the taste 

 of sulphate of quina of known good quality may be compared 

 with that of another sample. Thus when pure, a grain of 

 sulphate of quina will render nearly a pound and a half of 

 water, or 10,500 grains, sensibly bitter. 



3rdly. The alkalies either pure or their carbonates, if but 

 slightly in excess, always occasion precipitation at ordinary 

 temperatures in a solution of sulphate of quina containing only 

 l-1000dth of its weight, or less than one grain in two fluid 

 ounces of water. 



4thly. A solution of tannin occasions a very sensible pre- 

 cipitate in an aqueous solution of sulphate of quina, containing 

 only l-10,000dth of its weight of the salt, provided there be 

 no acid in excess. Kino is that form of tannin which best 

 answers the purpose. It is however to be observed, that the 

 salts of morphia, cinchonia, strychnia, &c. are similarly af- 

 fected by tannin ; but they are not likely to be mixed with 

 sulphate of quina. 



5thly. Sulphate of quina suspected to contain sugar, gum, 

 or other substances soluble in cold water, may be tried by di- 

 gesting the same portion of the salt in small and successive 

 portions of water to saturation. If the sulphate of quina be 

 pure, and the solutions all properly saturated, they will have 

 the same taste and specific gravity ; and similar portions will 

 yield by evaporation equal quantities of solid residuum. 



6thly. 



