. Journal . hat in gravimetric analysis these oxidisableand generally astringent non-tannins form only a smallportion of the whole. The close agreement of lightlj chromed powder with that officiallychromed, estabUshes the suitability of the former as adetaunising agent for the Lowenthal process, and encour-ages the hope that a dry chromed powder may ultimatelybe produced, which «ill avoid not only the chroming, butthe much more troublesome washing immediately Ijeforeuse which is now required. If the gelatine method is preferred to hide-powder forliquor control it is quite as rap
. Journal . hat in gravimetric analysis these oxidisableand generally astringent non-tannins form only a smallportion of the whole. The close agreement of lightlj chromed powder with that officiallychromed, estabUshes the suitability of the former as adetaunising agent for the Lowenthal process, and encour-ages the hope that a dry chromed powder may ultimatelybe produced, which «ill avoid not only the chroming, butthe much more troublesome washing immediately Ijeforeuse which is now required. If the gelatine method is preferred to hide-powder forliquor control it is quite as rapid, and probably less affectedby large amounts of non-tannins, but the results are notdirectly comparable with gravimetric analysis, and somesamples of gelatine exercise a slight reducing effect onpermanganate, not amounting in blank experiments tomore than about 0-2 per 10 of the non-tanninI filtrate, and probably due to traces of sulphites. Tliis,if desired, is easily determined and allowed DlSCTTSSION. Prof. W. JI. suggested the investigation of thetfect of reducing instead of oxidising substances ontmiins. The action of the latter was the basis of thelethods of estimation at present used. If a definiteibstance such as benzoic acid could be obtained as a?suit of reduction, mucli more definite results might be(itained. Under certain conditions tannic acid andany other phenolic bodies gave benzoic acid on reduc->n. Mr. F. W. BsAiisON asked if absolutely pure chemicalswere necessary when a correction factor could be used. Ml-. H. G. Bennett said that difficulties were alwaysexperienced with certain tannins where the methods ofestimation broke down. He emphasised the value of avolumetric method such as the Lowenthal method, wliichcombined speed and accuracy, since the hide-powderprocess involved difficulties such as the possible presenceof difficultly volatile substances like lactic acid, theimpossibility of drying the exhausted to a constan
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectchemist, bookyear1882
