摘要:

By combining A.C. and D.C. on the plate of a triode oscillator, more stable and much stronger oscillations were obtained than with pure D.C. Increases in radio frequency current up to 2.5 times were noted. Experiments with 200-cycle and 60-cycle A.C. showed that the higher frequency gave stronger oscillations.

ISSN:1923-4287    

DOI:10.1139/cjr30-063

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

This paper gives the results obtained when hydrogen peroxide is employed to oxidize malonic, tartronic, succinic, malic, tartaric, maleic and fumaric acids. The rate of reaction for each has been determined and compared with previous findings for other compounds. The mode of oxidation suggests in each case a complex through which decomposition occurs; the rates of reaction indicate the comparability of saturated acids having the same number of carbon atoms, the constancy of mono-hydroxylization in its velocity influence, and the diverse effects of hydrogen ion concentration. The effects of geometrical isomerism and the ethylenic linkage are well-marked. The formation of peracids is to be regarded in the nature of a side-reaction in these oxidations.

ISSN:1923-4287    

DOI:10.1139/cjr30-064

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

Methylation of sedosan (anhydro-sedoheptose) gives a tetramethyl sedosan, which on oxidation by nitric acid, yields an optically inactive trimethoxy glutaric acid. By esterifying the latter, and treating the ester with anhydrous methylamine, an optically inactive methylamide, presumably trimethoxy riboglutaro-dimethylamide is obtained. No trace of the methylamide of inactive dimethoxy succinic acid could be found. It is thus concluded that sedose possesses a 2:6 oxygen ring and that sedosan is an anhydro-sedopyranose.This is confirmed by the isolation of monotrityl sedosan, which shows that sedosan has only one primary alcohol group. Sedosan is therefore 2:7-anhydro-sedopyranose.The epimerisation of trimethyl δ-arabonolactone into trimethyl δ-ribonolactone apparently takes place only with great difficulty.The structure of sedosan is found to be in harmony with its lack of tendency towards polymerization, and this is in accordance with the views of Hibbert on the relation of structure to polymerization.

ISSN:1923-4287    

DOI:10.1139/cjr30-065

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

This paper describes modifications of the ordinary combustion apparatus for the determination of carbon and hydrogen in organic matter. These modifications were developed for analysis of coal, but are suited to more general use. It is claimed that they save time, and reduce the liability to error so that less practice and skill are required to obtain consistently good results. The combustion tube can be readily emptied, cleaned and repacked; with reasonable care it has a long life.

ISSN:1923-4287    

DOI:10.1139/cjr30-066

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

A method is described whereby the comparative areas of irregularly shaped microscopic objects may be rapidly determined. It consists of staining them with fuchsine and projecting their magnified images into a photo-electric cell insensitive to red light. The photo-electric current is inversely proportional to the sizes of the images and, at low magnifications, may be measured with a sensitive galvanometer.

ISSN:1923-4287    

DOI:10.1139/cjr30-067

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

The head lengths of horse spermatozoa have been measured in 51 samples and the measurements plotted in frequency distribution curves. These curves are unimodal and their coefficients of variation range from 4.00 to 6 00 (or slightly less). A coefficient in excess of 6.00 indicates an unsound sire, and animals from which skew curves are obtained may be regarded with extreme suspicion since they are not obtained in the case of normal animals. Generally the findings are in harmony with cytological data available, but both require further study before they can be reduced to a systematic basis.

ISSN:1923-4287    

DOI:10.1139/cjr30-068

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

Factors affecting drought resistance include those concerned in absorption, transpiration, and wilt endurance. The colloidal properties of leaf-tissue fluids are believed to be important in water retention under droughty conditions. These and other physico-chemical properties have been determined in a number of cereals, grasses and other plants, in relation to known drought adaptations. Methods for the study of colloidal properties have also been investigated.Hydrophilic colloids bind water and increase the concentration of aqueous solutions, as shown by freezing-point determinations. Dextrose is less effective than sucrose in demonstrating this phenomenon. Concentration, quality, and state of dispersion or coagulation of colloids are factors affecting the degree of water binding.The extraction of plant-tissue fluids and the estimation of dry substance by a modification of the refractometric method are described. The hydrolysis of sucrose added to plant juice in the bound-water determination is shown experimentally not to introduce serious errors. Storage of leaf tissue or press juice for a few hours even at 0 °C. leads to changes in colloidal properties, but errors from this source are avoided by prompt handling.Cylindrical dialyser sacs of 100 cc. capacity were found to require about 48 hr. for dialysis of plant juice at 3 °C., with the water changed every hour. A gradual partial coagulation of colloids took place during dialysis, as shown by a decrease in refractive index, by an increase in gold number, and by sedimentation when centrifugalized. Hydration and dispersion were not always related, though both were affected by hydrogen ion concentration and by salts. Acid and alkaline salts stimulated hydration less because of the opposing "salt effect". In the presence of the natural crystalloids, hydration was usually greater than in dialysed juice.The osmotic pressure of the tissue fluids of crop plants has been found to vary with physiological scarcity of water, but is not a reliable index of drought resistance. Bound-water content has been found more dependable; the cultivated wheats and several grasses have been on this basis satisfactorily arranged in the order of their drought resistance. The contrasting behavior of two poplar species, with reference to leaf fall and frost resistance, has also been explained. The separation of the colloids by dialysis and the determination of their gold number have been used as aids in interpreting the bound-water values.The method of measuring imbibition pressure by direct pressure on masses of leaves proved unsuitable. The rates of water loss by evaporation from cactus segments and detached leaves of two grasses, under controlled humidity conditions, proved the remarkable ability of the cactus to retain moisture, but in the grasses showed no relation to drought resistance.

ISSN:1923-4287    

DOI:10.1139/cjr30-069

出版商:NRC Research Press    

年代:1930

数据来源: NRC