The chemical character of so-called iodo-tannin compounds / by Frederick B. Power and Frank Shedden.

  • Power, Frederick B. (Frederick Belding), 1853-1927
Date:
[1901]
Catalogue details

Licence: In copyright

Credit: The chemical character of so-called iodo-tannin compounds / by Frederick B. Power and Frank Shedden. Source: Wellcome Collection.

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    (a) 50 C c of this solution were diluted with water, and heated on a water-bath with a little dilute sulphunc acid and an excess of silver nitrate. 0-4112 gramme of silver iodide Wc s obtained, corresponding to 0-2222 gramme of iodine, or to 1-1110 gramme of iodine in 250 C.c. of liquid. The filtrate from the above was heated with a little fuming ni ric aci , when an additional 0-0028 gramme of silver iodide was obtained, corresponding to 0‘0015 gramme of iodine, or to 0*0075 gramme in 250 C.c. The total amount of iodine found was thus. 1-1110 + 0-0075 = 1-1185 gramme, as compared with rimo gramme, the amount originally taken. 5 (6) Another portion of 50 C.c. of the liquid was treated with hide powder, and the filtrate therefrom acidulated with nitric acid and precipitated by silver nitrate. 0‘2586 gramme of silver iodide was obtained, corresponding to 0-1397 gramme of iodine The hide powder was then treated with a dilute solution ot sodium carbonate, filtered, and the filtrate acidulated with nitric acid, when a precipitate was produced which was filtered oil, but neither this precipitate nor the remaining hide powder then gave any reaction for iodine. The filtrate, however, gave with silver nitrate an additional 0-1526 gramme of silver iodide, corresponding to 0‘0825 gramme of iodine. The total amount of iodine found was thus : 0-1397 + 0-0825 = 0-2222 gramme, as compared with 0-2238 gramme originally contained m the 50 C.c. of solution employed. (c) Another portion of 50 C.c. of the liquid was first concen¬ trated to a small bulk on a water-bath, and then kept m a vacuous desiccator over lime and sulphuric acid for two or three days. The dry residue was in the form of light brown scales, which were slowly soluble in water, and which would coires- pond to the so-called iodo-tannin compound obtained by Bar- nouvin (loc. tit.). The solution of this substance gave a slight purple colour to chloroform, showing the presence of a little free iodine, but it also afforded an intense blue-black colour with ferric chloride. On the addition of sodium chloride a precipitate was obtained similar to that produced in a solution of tannin, but which contained no iodine. From the. solution, acidulated with nitric acid, the whole of the halogen was pre¬ cipitated by silver nitrate. A little of the substance was boiled with acetic anhydride. A part of this liquid was diluted with hot water and another part with alcohol, but in both cases the precipitated products contained no iodine. 10488 grammes of the above-described scales, in the form of powder, were heated