摘要:

From careful measurements of the relative flow times of solutions of GR-S in benzene, it has been established that the intrinsic flow time (and hence the intrinsic viscosity) of GR-S in benzene may be most precisely determined by the use of a function, based on the Baker equation relating ηr, the relative viscosity, andc, the concentration; for the GR-S–benzene system the value ofnmay be taken as 8. For the greatest precision [t] is determined by linear (horizontal) extrapolation, to zero concentration, of thevs.cplot; in rapid routine work [t] may be evaluated asby measurements on only one solution of a concentration such thattr = 1.8 ± 0.4.

ISSN:1923-4287    

DOI:10.1139/cjr47b-037

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

The intrinsic viscosity, [η], (as well as the intrinsic flow time, [t], and the intrinsic kinematic viscosity, [ν]) of normal GR-S in benzene has been shown to be independent of temperature, over the range 10° to 55 °C, within the experimental precision. In this range of temperatures, also, the functionsandare independent of concentration (up to at least 0.3%), and may therefore be used in the one-point determination of [t] and [ν].

ISSN:1923-4287    

DOI:10.1139/cjr47b-038

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

The composite self-weakening relations for La140and Ba140have been measured. Using these data, the growth of the La140daughter from the Ba140parent has been studied and compared with the growth calculated from the radioactive dependence laws. It is shown that, in the comparison of the activities of different β−emitters, there is a danger in the use of corrections obtained by extrapolations of self-weakening and external absorption data.

ISSN:1923-4287    

DOI:10.1139/cjr47b-039

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

The fission yields for Ba139and Ba140for thermal neutron fission of U235and fast fission of U238have been measured using naturally occurring uranium. This was accomplished by comparing the barium fission product activities with the U239formed in radiative capture. With these data the fission yields were calculated from known values of the cross-sections for thermal fission and capture in uranium and were found to be 6.1% and 5.6% for Ba139and Ba140, respectively, for thermal fission and 5.1% and 4.2% for Ba139and Ba140, respectively, for fast fission. The contribution of resonance fission to the thermal neutron effect has been shown to be less than 5% in the irradiation arrangement used.

ISSN:1923-4287    

DOI:10.1139/cjr47b-040

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

The ratio of I131(8.0 days) to Ba140has been determined in neutron fission of uranium and the fission yield of the former calculated to be 2.23 × 10−2from the previously reported value for Ba140. This in turn permits the estimation of fission yields for the 132, 134, and 136 fission chains, the relative abundance of which, together with that of 131, has been obtained by Thode. The ratio of 54 min. I to Ba139has been determined. Using the previously reported value for the fission yield of Ba139, that for the iodine was found to be 5.75 × 10−2. A mass of 134 is assigned to the 54 min. I on the basis of Thode's data.

ISSN:1923-4287    

DOI:10.1139/cjr47b-041

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

In attempts to synthesize 10-pyrido(3,4-b)carbazole, a number of new compounds were prepared. These are β-(5,6,7,8-tetrahydro-3-carbazolyl)propionic acid, β-(5,6,7,8-tetrahydro-3-carbazolyl)ethylamine and their intermediates.

ISSN:1923-4287    

DOI:10.1139/cjr47b-042

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

Cyanogen chloride, prepared by the method of Jennings and Scott, has been fractionally recrystallized to a constant freezing point of −6.90 °C. Vapour pressure values for material purified in this way are in good agreement with the data of Klemenc and Wagner. The activation energy for the hydrolysis of cyanogen chloride at pH 4 to 6 between 0° and 50 °C. is approximately 21 kcal. per mole.

ISSN:1923-4287    

DOI:10.1139/cjr47b-043

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

Rate curves have been determined for the reaction of ammonia and formaldehyde in aqueous solution at 0 °C. and 35 °C., over a range of initial mole ratios (formaldehyde: ammonia) of 0.25 to 2.0. For each set of conditions, three curves have been obtained on the basis of ammonia consumed, formaldehyde consumed, and material precipitated with mercuric chloride respectively.At 0 °C. the three rate curves tend to approximate one another in a large excess of ammonia but are widely separated in excess formaldehyde. The reverse is true at 35 °C. The reaction is characterized by a high initial rate of formation of hexamine, this rapid rate being maintained to a lower yield of hexamine the more dilute the solution. The existence of a stable by-product in excess formaldehyde is indicated by the variation in final yields of hexamine, when these are calculated on the basis of formaldehyde consumed, ammonia consumed, or material precipitated with mercuric chloride.A mechanism for the reaction has been suggested.

ISSN:1923-4287    

DOI:10.1139/cjr47b-044

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

A direct action shunt selector has been designed that pre-selects the appropriate shunt so that widely different mass spectrometer ion currents can be recorded linearly on a standard chart. In conjunction with a linear direct current amplifier and a Leeds and Northrup Speedomax pen recorder, this unit allows rapid and accurate recording of a given mass spectrum, which can be scanned by varying either the magnetic field or the ion accelerating potential of the mass spectrometer. When used with a 180° Nier type mass spectrometer with well stabilized circuits, a precision of ± 0.2% in measuring the ratio ofandwas obtained. Also, samples of xenon were investigated and the abundances of the isotopes determined.

ISSN:1923-4287    

DOI:10.1139/cjr47b-045

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

The formation of ethanolamines from ethylene oxide and ammonia is a case of simultaneous, consecutive, competitive second order reactions. The results obtained show the time at which to stop a reaction for a maximum yield of any one of the three products. It is shown that as the reaction proceeds from ammonia to monoethanolamine to diethanolamine to triethanolamine the velocity constants are in the ratio of 1:6:4 for the three reactions. The values of the velocity constants are determined graphically. From these values an energy of activation of 16,600 cal. is calculated and is the same for each step. There is an indication that a tetraethanol – ammonium hydroxide is slowly formed.

ISSN:1923-4287    

DOI:10.1139/cjr47b-046

出版商:NRC Research Press    

年代:1947

数据来源: NRC