摘要:

Wheat straw holocellulose, after soaking in liquid ammonia for 36 hr. at room temperature, was fractionated by successive extractions with cold water, 0.5% sodium carbonate, 0.5% potassium hydroxide, and 2.2% potassium hydroxide. Pretreatment with liquid ammonia increased the material soluble in cold water from 3% to 20.2%. Hemicellulose fractions were precipitated from the extracts by ethanol. A complete analytical balance was obtained by estimating ash, pentosan, uronic acid anhydride, acetyl, and methoxyl contents of the original holocellulose, of each of the fractions and of the residue. Analyses of the isolated fractions showed some systematic differences, with pentosan contents increasing and uronic acid anhydride decreasing progressively in the alkali soluble fractions. D-xylose, L-arabinose, D-glucose, D-galactose, and hexuronic acid in approximate molar ratios of 40:7:2:1:4 were found in the hemicellulose fractions. The presence of the sugars was confirmed by isolation of crystalline derivatives. A uronic acid complex, resistant to hydrolysis, was isolated and the components shown to be D-xylose and a monomethoxyl galacturonic acid.

ISSN:1923-4287    

DOI:10.1139/cjr50b-093

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The copper salts of the basic amino acids (arginine, histidine, lysine, and ornithine) are formulated as complex salts. They contain a cation (with two positive charges) consisting of a copper atom and two amino acid molecules. The anion can be a simple inorganic group, such as Cl−, NO3−, SO4=. The complex copper amino acid cations form double complex compounds with anions HgI3−or HgI4=. The double complex salts of arginine, [Cu(C6H14O2N4)2][HgI4], and lysine, [Cu(C6H14O2N2)2][HgI3]2, are only slightly soluble in water and have characteristic crystal forms. They can be used for the quantitative determination of these amino acids. The copper salts of the natural amino acids are classified into four groups.

ISSN:1923-4287    

DOI:10.1139/cjr50b-094

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Based upon an assumed mechanism of particle aggregation by shear-induced interparticle collisions, a new method of studying flocculation in suspensions of large particles is described, and representative results obtained with cellulose–fiber suspensions are presented. The method consists in subjecting the suspension to a reproducible condition of shear motion and analyzing the fluctuations in optical transmission coefficient electronically. An approximate statistical theory is presented on the basis of which a flocculation index (σ/N0) appropriate to the method is proposed. The index is a function of both the number and size of the aggregates. The flocculation index was found to decrease with increasing rate of shear and decreasing fiber length. The effect of concentration and of additives was investigated. Alternative experimental techniques are outlined and limitations to the present method are pointed out.

ISSN:1923-4287    

DOI:10.1139/cjr50b-095

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

A volumetric procedure is described for determining small amounts of iridium (from 2 to 20 mgm.). A solution of the metal is heated to dense fumes with sulphuric acid, cooled, diluted with water, and then oxidized with an excess of cerium (IV) sulphate solution. The resultant solution is titrated with a standard 0.01 Niron (II) sulphate solution, the course of the titration being followed potentiometrically. In solutions containing other platinum metals it has been found possible to determine iridium directly in some cases by this procedure; in other cases it was found necessary to remove osmium as the volatile tetroxide prior to oxidizing with cerium (IV) sulphate. The method is probably less accurate than existing gravimetric procedures, but offers considerable advantage in simplicity.

ISSN:1923-4287    

DOI:10.1139/cjr50b-096

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The kinetic equations of the adsorption wave were applied to the oxidation of carbon monoxide in an air stream by granular silver permanganate – zinc oxide reagent. The following relations have been investigated in this system: (a) the concentration of the escaping gas as a function of time, (b) the effect of initial concentration, column length, and flow rate on breakdown time, (c) the influence of granule size on breakdown time and rate of reaction. The critical column length was found to be dependent on flow rate and independent of initial concentration. Critical column lengths of approximately 0.4 cm. to 1 cm. were found for the range of flow rates studied. The relation found between granule size and breakdown time does not completely agree with the theoretical equations. As the mean diameters of the granules decreased from 2.2 mm. to 0.90 mm. the breakdown time increased, but a decrease in mean diameter from 0.90 to 0.30 mm. resulted in a reduction of breakdown time. Although the results are in general agreement with the equations developed by Hinshelwood and Klotz, certain deviations from the theoretical treatment were evident.

ISSN:1923-4287    

DOI:10.1139/cjr50b-097

出版商:NRC Research Press    

年代:1950

数据来源: NRC