The interactions of colored metal chelates of ethylenediaminetetraacetic acid with various metal ions were determined by a direct spectrophotometric method in nitrate and perchlorate media. Under conditions such that the metal chelates are not appreciably dissociated and the chelate containing one metal ion per ligand was the important form, the measurements allowed calculation of the relative stability constants of the metal chelates investigated. The dissociation of the nickel(II)ethylenediaminetetraacetate chelate was followed spectrophotometrically, the absolute value of the stability constant of this chelate was calculated, and the relative values for the other metals were converted to absolute stability constants. Studies were also made of the effect of ionic strength on the stabilities of the chelate compounds.
Previous work [9] on the degradation of cotton during mechanical processing has been extended to include a study of the action of the pickers under various operating conditions. The results indicate that blade and carding beater types cause different amounts of degradation, that the amount of degradation caused by a very close setting can be differentiated from that due to wider spacings, and that the speed of rotation of the beater has a degradation effect which is detectable only after several passes—i.e., several consecutive picker operations. The effect of consecutive picker operations under similar conditions of the other variables is readily discernible. IN A RECENT INVESTIGATION [9] it wassuggested that cotton degrades during the normal processing operations which convert the seed cotton to yarn. Evidence of this degradation was based upon the progressive reduction in D.P. of a given cotton as it was mechanically processed, the viscosity of cotton in cupriethylene diamine being used as an index of D.P. Hess et al. [6] and Forziati et al. [5] have also reported reduction of D.P. of cellulose during purely mechanical treatment, although the results in both of these cases were obtained on much more drastic treatments. All three of the reports cited concluded that mechanical energy could be absorbed by the cellulose and utilized to break valence bonds.In the light of these conclusions, it seemed desirable to extend the experimental work, concentrating on the damage incurred in a single operation, with specific study of controllable variables in the operation. In the work presented here, special attention was given to the action of the beaters in the picking operation, since previous evidence showed [9] that this operation was the most drastic in causing degradation. The Saco-Lowell Shops processed the cotton to provide information on the effects of beater type, speed (r.p.m.), setting, and repetition of passes through beating equipment.It has been argued that the damage during mechanical processing is not important with respect to that which occurs during later chemical processes such as kier-boiling or bleaching. However, a recent paper which reported studies on rain-grown and irrigated cottons [10] does not support this argument. Observed D.P. differences on samples from two stages of mechanical processing indicated degradation but were not large enough to be statistically significant (probably due to sensitivity of the method employed, which was entirely adequate for the purposes intended). However, after these samples of card sliver and combed yarns had been given identical scouring treatments, significant differences existed. Thus, although the data are not extensive, there is strong statistical evidence to indicate that the small changes in D.P. incurred during mechanical processing persisted and were not lost in the subsequent chemical treatments. An appreciable portion of the difference in D.P. of the two raw cottons also persisted through the mechanical and chemical treatments. Further experimen...
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