The accessible regions in cotton cellulose were tagged by the introduction of diethyl‐aminoethyl (DEAE) substituents at DS = 0.034 without other substantial changes in structure. Evidence from rates of hydrolysis of this DEAE cotton to hydrocelluloses and from the composition and structure of the solubilized and insoluble fractions provides the basis for considerable detail regarding two types of accessible regions in the cotton fiber; these are identified as accessible surfaces of elementary fibrils. One type of accessible surface is characterized by molecular chain segments which are distorted and disordered by tilt/twist strain that is concentrated in this segment of the elementary fibril; the second type of accessible surface is characterized by a relatively high degree of order which reflects the high level of crystallinity within the interior of this unstrained segment of the elementary fibril. Substantial differences between these accessible surfaces are discussed. It is estimated that chain segments on accessible surfaces of the first type are substantially disordered, i.e., approximately 60–90% of the D‐glucopyranosyl units are dislocated from positions of perfect crystalline order. Accessible surfaces of the second type are quite highly ordered, i.e., only 5–30% of the D‐glucopyranosyl units dislocated.

The table shows some typical results obtained by this method with samples containing known amounts of iodine. The iodine was added in the form of potassium iodide to samples of mineral mixture containing no iodine or a very slight trace. Blanks were always run on the samples used and on the reagents.Samples which contain no charcoal or bone meal may be fused with 20 g. of sodium hydroxide alone, omitting the potassium nitrate except for the addition of a few small crystals at the end of the fusion. Summary A method is described for the quantitative determination of small amounts of iodine in mixtures of mineral salts, charcoal, spent bone black, etc. The method is a modification of Kendall's and involves fusion with sodium hydroxide and potassium nitrate, removal of interfering substances, oxidation with bromine and determination of the iodine iodimetrically. Necessary conditions are outlined. Other methods were found very unsatisfactory for complex mixtures except when the samples were freshly prepared. Quincy, Illinois

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In the first description of cis-aconitic acid, Malachowski and Maslowski (1) noted that in aqueous solution it was rapidly converted by heat into the transacid. In a study of the electrical conductivity of dilute solutions of the two isomeric acids, Malachowski (2) found that the proportion of the trans-acid in equilibrated mixtures is approximately 85% and decreases slightly with elevation of the temperature and with dilution of the solution. Krebs and Eggleston (3) showed that in neutral solution sodium cis-aconitate is much more stable and that the most rapid and extensive conversion to the irans-isomer takes place in strongly acidic and strongly alkaline solutions. They point out, however, that the values they obtained are of uncertain accuracy because of interferences in the enzymic and chemical reactions used to determine cis-aconitic acid.The strontium salt of irans-aconitic acid ( 4) is soluble when formed by double