Quinometry
The method of estimating the quantity of quinine in cinchona bark and the salts obtained from it. The following tests give very accurate results in examining the bark; and the salts are tested in the same way, but the result is not quite so accurate, as it includes any quinidine (see No. 4028) that may be present in the quinine; and makes, therefore, the apparent richness of the sample greater than it really is. (Cooley.) When the base is insoluble in water, nonvolatile, and existing in the plant in an insoluble form. Boil or macerate the bruised plant in water acidulated with muriatic acid, filter, neutralize the acid with an alkali, (ammonia, lime, or magnesia), and collect the precipitate, which must be purified by resolution in dilute acid, digestion with animal charcoal, and subsequent crystallization or precipitate with a sufficient quantity of a conprecipitation by an alkali; or the first precip- centrated solution of carbonate of soda. Heat itate may bo purified by dissolving it repeat- the fluid until the precipitate is dissolved; edly in alcohol. 4026. Test for the Strength of Quinine. Make a decoction of 100 grains of bark in 2 fluid ounces distilled water; filter, and and when cold, dry and weigh it. It should
When the base is insoluble in water, and weigh 2 grains or more, and dissolve entirely non-volatile, but existing in the plant in a solution of oxalic acid. To render the soluble state. Boil or macerate in hot water result strictly accurate, the bark should be as before; filter and precipitate by adding an alkali; purify as last.
When the base is soluble in water, and non-volatile. Mako an infusion with a dilute acid (muriatic); concentrate by a gentle heat; treat the liquor with potassa and ether (conjointly); decant and evaporate. exhausted with ether, and the mixed solutions evaporated. Salts of quinine may be tested in the same manner. (Cooley.)
4027. Test for the Percentage of Quinine in Bark, &c. Exhaust 100 grains of bark with acidulated water; filter the solution, and render it alkaline with liquor of When the base is both soluble in water and potassa; next agitate it with about 1/80 its volatile. The vegetable or its extract may volume of chloroform, and allow it to repose be mixed with potassa and distilled; the a short time; the chloroform, holding the alproduct, neutralized with oxalic or sulphuric kaloid in solution, sinks to the bottom of the acid, carefully evaporated to dryness, and vessel in a distinct stratum, from which the digested in alcohol, and this solution agitated supernatant liquid must be separated by dewith potassa and ether; the ethereal solu- cantation; the chloroformic solution, either GAS. at once or after being washed with a little 4031. Pneumatic Trough. A vessel cold water, is allowed to evaporate, and the or tank nearly filled with water, provided weight of the residuum in grains gives the with a shelf placed 1 or 2 inches below the percentage of richness of the sample. Ether surface. The receiving bottles are first immay be used instead of chloroform, but the mersed in and filled with the water and then ethereal solution will form the upper stratum placed neck downwards on the shelf, which instead of the lower. This test is also appli- is furnished with holes to allow of the passage cable to the salts of quinine, but with restric- of the gas into the receivers from the connecttions referred to in No. 4025. (Rebourdain.) ing tube, the end of which is brought imme-