摘要:

A study has been made of methods for the removal of nitrogenous constituents from plant tissues prior to determination of their lignin contents. It was found that substitution of a continuous extraction method for the usual treatment with hot 1% hydrochloric acid had little effect on the amount of lignin isolated but apparently lowered its methoxyl content. Continuous extraction thus appears to cause some demethoxylation of lignin. Treatment with cold 5% acetic acid apparently can be substituted for the hot 1% hydrochloric acid extraction with very young but not with older, undried tissue. Ether saturated water was found to be the most satisfactory nonacid extractant for removal of nitrogen-containing material from young undried tissues. Upwards of 90% of the original nitrogen can be removed from such material by three extractions with this solvent. With older tissues or with material that has been dried, this proportion of the nitrogen cannot be removed except by extraction with hot dilute mineral acid.

ISSN:1923-4287    

DOI:10.1139/cjr48b-045

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

The effects of maintaining reducing conditions during both the pretreatment procedures and the final determination of lignin in plant tissues have been investigated. In studying the effects produced, consideration has been given, not only to the quantity of lignin obtained, but also to its quality as judged by its methoxyl and nitrogen contents. The introduction of hydrogen sulphide during the pretreatment procedures had little or no effect on the amount or the composition of the lignin fraction isolated from freshly harvested oat plants. With air-dried timothy, introduction of the hydrogen sulphide apparently prevented in a large measure the usual interference by nitrogen-containing substances. The presence of hypophosphorous acid in the 72% sulphuric acid had no effect on the final results. Constant boiling hydriodic acid was unsatisfactory as a substitute for 72% sulphuric acid in the final determination.

ISSN:1923-4287    

DOI:10.1139/cjr48b-046

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

A method of determining the lignin content of fresh plant tissue without preliminary drying has been devised. Prior to the final lignin determination with 72% sulphuric acid, the tissue is cut up, extracted with ether saturated water in a Waring Blendor, refluxed with 1% hydrochloric acid, and finally extracted with ethanol–benzene. For comparison, determinations were carried out by the above method and the standard A.O.A.C. procedure on material that had been air-dried at room temperature. Both greenhouse and field grown oat plants cut at various growth stages were used in this study. The modified method gave lower lignin values than the standard procedure with young succulent tissue. This difference decreased as the age of the tissue increased, and the results by all methods were very similar with oat straw. That the modified procedure on fresh tissue removes more interfering nitrogenous material than the other methods used is indicated by the lower nitrogen content of the lignin isolated. The absolute methoxyl contents of the residues isolated from dried tissue were greater than of those isolated from fresh material (from the same source). This may have been due to the inclusion of more methoxyl-containing carbohydrates in the former residues.

ISSN:1923-4287    

DOI:10.1139/cjr48b-047

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

The limits of inflammability of hydrogen cyanide – air mixtures at room temperature and approximately 1 atm. pressure, have been determined to be 7.8 and 42.4 volume % of hydrogen cyanide. The effect of the addition of cyanogen chloride, phosgene, chloroform, hexane, heptane, and methyl chloroformate upon these limits has been investigated. It was found that the minimum molar ratio of added vapor to hydrogen cyanide that will produce a mixture that never becomes inflammable when progressively diluted with air is equal to 4.7 for cyanogen chloride, 0.86 for phosgene, and 1.1 for chloroform. All mixtures of hexane, heptane, and methyl chloroformate with hydrogen cyanide become inflammable when suitably diluted with air. For these systems, Le Chatelier's law, dealing with the composition of limit mixtures of two inflammable gases with air, was found to hold.

ISSN:1923-4287    

DOI:10.1139/cjr48b-048

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

Viscosity and osmotic pressure measurements were carried out on dilute benzene solutions of aluminum dicaprylate, dilaurate, dimyristate, dipalmitate, distearate, and monostearate. From the results it is concluded that these soaps are polymers of high molecular weight formed by weak intermolecular links which are assumed to be hydrogen bonds. Lowering of the molecular weight by dissociation of these bonds is responsible for decreases in solution viscosities. Variations of the molecular weights obtained (60,000 to 900,000) are due, in the main, to the effect of concentration and aging on the extent of this dissociation.

ISSN:1923-4287    

DOI:10.1139/cjr48b-049

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

X-ray investigations by means of powder photographs show that solid solution formation between potassium nitrate and ammonium nitrate in simple admixture after grinding together may take place, and is considerably accelerated when the temperature is raised from ordinary temperatures to above 40 °C., at which NH4NO3III is stable (transition temperature 32 °C.). The preparation of homogeneous mixed crystals of ammonium nitrate and potassium nitrate by co-crystallization of the salts from aqueous solution is described.

ISSN:1923-4287    

DOI:10.1139/cjr48b-050

出版商:NRC Research Press    

年代:1948

数据来源: NRC