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It is somewhat surprising that eutectic melting takes place under the circumstances described, in view of the lack of an intimate mixture of the two components. However, the eutectic is very sharp in some cases, as shown by the photomicrographs of Figure 1. This series of pictures shoms unmistakable melting of Xylon type 6 with p-nitrophenol at approximately 40' C. below the melting point of p-nitrophenol and about 140' C.below the melting point of Kylon type 6 . Figure 1, a, shows txo filaments surrounded by fragments of p-nitrophenol crystals just before melting has begun. In Figure 1, b, melting has begun as evidenced by the curved, slightly sir-ollen, and irregular outline of the filaments, and the rounding off and coalescing of pnitrophenol fragments. As the temperature continues to rise the melting proceeds faster and more obviously as shonm in Figure 1, c and d. If at this point the slide is shifted to show a field containing an excess of p-nitlophenol, the fibers can be seen to dissolve completely at temperatures well belorn7 the melting point of p-nitrophenol I t IS believed that the relatively high vapor pressure of the p-nitrophenol is responsible for the successful eutectic melting, the fibers being bathed with vapor of p-nitrophenol Tithin the confines of slide and cover glass. Of a 1589 number of compounds surveyed as possible reference reagents, only those which exhibited a strong tendency to sublime also exhibited eutectic melting.The results obtained also indicate the potential utility of fusion methods for other studies with synthetic fibers. For example, the change in the sign of elongation that occurs when Orlon is heated indicates structural changes in the nature of a second order transition. LITERATURE CITED(1) Am. Assoc. Textile Chemists Colorists, Tentative Test RIethod Nitrate determinations have lacked specificity in many methods described in the literature. The specificity of the test reported is based on the reduction of nitrate to nitrite by a microbiologically produced nitrate reduc-Lase. The method is simple and equipment is easily assembled. The nutritional requirements of the microorganisms are met by trypticase. Kitrate may be determined in the presence of many compounds known to interfere in other methods. The range of the test is from 2 to 20 y of potassium nitrate, with a reproducibility of 1 0 . 1 2 y. POSITIVE correlation between a qualitative test for nitrateA and the toxicity of forages produced in drought areas (8) led t o a need for a rapid, quantitative method for determining nitrate. hlany methods described in the literature are based on determining nitrate nitrogen by difference or by extraction and nitration of organic compounds. It requires either a separation of the nitrate nitrogen from the total water-soluble nitrogen or a total nitrogen determination and a standard Kjeldahl determination. The actual distillation step in the Devarda method is rather difficult. The Robertson method ( d ) , like the Devarda method, is not applicable in the presence of cyanamide or ...

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Systematic studies on the fractionation of serum proteins on gradient-eluted columns of concanavalin A-Sepharose have been carried out to determine if the oligosaccharide residues were sufficiently different to permit a reasonable separation and to determine where in the chromatogram these proteins would be eluted. Human whole serum and ammonium sulfate fractions derived therefrom were used in conjunction with 2.1 x 75 cm columns of concanavalin A-Sepharose and a 4 x 400 ml gradient (Varigard) with 0.5 M methyl alpha-D-glucopyranoside as limit buffer. The elution positions and chromatographic limits of 14 well-characterized human serum proteins have been determined by double diffusion of aliquots of the effluent fractions (10X concentrated) in agarose gel against specific antibody and the general chromatographic distribution of the proteins by immunoelectrophoresis. Overall, the results demonstrate that the composition of the oligosaccharide side chain, like differences in molecular size, solubility, and charge density, is a useful parameter in the chromatographic separation of protein from serum. Although it is well-known that albumin is a nonglycoprotein, 1.0% of the protein was tightly bound by concanavalin A-Sepharose. Subsequent experiments showed that albumin binding was due to complex formation with IgA and IgG both of which possess the necessary complement of concanavalin A-reactive residues for strong binding. Sodium dodecylsulfate polyacrylamide gel electrophoresis of 2-mercaptoethanol-reduced albumin-IgA and -IgG complexes produced bands corresponding to the molecular weights of albumin and the heavy and light chains of IgA and IgG whereas unreduced samples were not dissociated. When these complexes were reacted with concanavalin A-Sepharose and treated with 2-mercaptoethanol, free albumin was eluted. The remaining adsorbed glycoprotein(s), IgA and IgG, could be eluted with methyl alpha-D-glucopyranoside. These results strongly suggest that these proteins and albumin are linked via a disulfide bond(s).