Quinidine
An alkaloid found in diately under one of the holes. For gases quinia which has been prepared by precipita- which are easily absorbed by water, mercury tion. It is distinguished from quinine by or some other fluid is necessary in place of not striking a green color when treated with the water. As the gas ascends into the rechlorine followed by ammonia, as quinine ceiving bottle, the water is displaced; when does. In medicinal character its powers are full, and the gas begins to escape, the bottle comparatively feeble. It is present in nearly should be closed with a greased stopper, and all the ordinary sulphate (disulphate) of removed from the trough. quinine as sold, either through careless pre- 4032. To Find the Weight of a Gas. paration or wilful adulteration, and is not de- Multiply the specific gravity of the gas by tected by, and consequently included in, the 309 (the weight in grains of 1000 cubic inches results of the usual tests for quinine. (See of air), the product will be the weight of 1000 Nos. 4025, &c.) Cinchonine is another fee- cubic inches of the gas. bler alkaloid also found in quinia. 4029. Ure's Test for the Presence of Quinidine or Cinchonine in Quinine.
This test is applicable to quinine salts gener- 4033. To Prevent the Escape of Gas from India-Rubber Tubing. India-rubber tubing is slightly permeable to gas. The amount which escapes through the walls of ally, but more especially refers to the sul- the tube is very small; but it may be advisphate (disulphate) of quinine. Place 10 grains able sometimes to render an escape impossiof the salt into a strong test tube, furnished ble. This can be done by giving the tubing a with a tightly-fitting cork; add 10 drops of a thin coating of a varnish made by dissolving mixture of 1 part sulphuric acid and 5 parts 1½ parts molasses and 2 parts gum-arabic in water, and 15 drops water, accelerating so- 7 parts of white wine and 34 parts strong allution by a gentle heat. When dissolved and cohol. The molasses and gum must first be entirely cooled, add 60 drops officinal sul- dissolved in the white wine, and the alcohol phuric ether with 20 drops spirits of ammonia, close the test tube with the thumb, and shake it well; cork the tube closely and shake gently from time to time, so that the bubbles of air may readily enter the layer of ether. If the salt be free from, or contain no greater proportion than 10 per cent. of quinidine, it will be entirely dissolved; while on the surface of contact between the two strata of fluid, the mechanical impurities only will be separated. From this it appears that 10 grains of the salt may contain 1 grain of quinidine, and still a complete solution take must be added very slowly, constantly stirring the mixture, or the gum will be thrown down.