摘要:

AbstractExposure tests have been made on paint films prepared from an emulsion paint containing phenyl mercuric acetate (PMA) labelled with203Hg. Loss of mercury from the films has been followed radiometrically.Films exposed indoors in a confined space (no air circulation) showed little, if any, mercury loss for up to 8 months. Films exposed in the open laboratory lost from 20 to more than 60% of mercury after 250 days. This agrees qualitatively with the results of other workers on similar paints. At 50°, films lost mercury at rates about 10 times greater than those at ambient temperature.Films exposed out‐of‐doors lost the majority of their mercury after a few days of rain. Pre‐treatment of films, e.g. by u.v. radiation, had no effect on their subsequent outdoor behaviour. Even well‐dried films lost mercury at the same rate as newly applied films.Films with a low PMA content (0·02% Hg) lost mercury at a higher percentage rate than films with a high one (0·2% Hg). Thick films (0·002 in.) lost mercury at a lower rate than thin ones (0·001 in.). A mercury‐free top coat also reduced loss rate. All loss rates decreased with increasing time. These trends applied to all the exposure conditions studied.Mercury loss appears to be due to both volatilisation and dissolution of PMA and not to decomposition. The results indicate a non‐homogeneous distribution of PMA throughout the paint film, and a diffusion‐

ISSN:0021-8871    

DOI:10.1002/jctb.5010190101

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe fungicides, phenyl mercuric dodecyl succinate (PMS) and phenyl mercuric dimethyldithiocarbamate (PMDDC), have been prepared labelled with203Hg. Comparative exposure tests have been carried out on emulsion paints each containing one of the labelled compounds phenyl mercuric acetate (PMA), PMS, or PMDDC.After 236 days of indoor exposure, approximate losses from films are 60 (PMA), 50 (PMS), and 20% (PMDDC). Relative losses from films of low‐Hg content (0·02%) are a few per cent higher than those from comparable films of high‐Hg content (0·2%).After 56 days of outdoor exposure, approximate losses are 95 (PMA), 90 (PMS), and 40% (PMDDC). PMS and PMDCC films of high‐Hg content show relative losses slightly higher than those of low‐Hg content; a behaviour opposite to that of PMA films. This may be due to the distribution of PMS or PMDDC through a paint film being less uniform than that of PMA. A correlation between mercury loss and rainfall is observed for all three fungicides.The loss rates from all films decrease with time during indoor exposure. Out‐of‐doors, this decrease becomes well defined only when a substantial portion of the fungicide has been removed by rain.The results indicate that in emulsion paint films, under the exposure conditions used in this work, PMS is retained slightly better than PMA, but that PMDDC is retained much better than either. The high retention of PMDDC is probably due to its low saturation vapour pressure and to its low solubility in water.The solubility of PMDDC in water at 20° has been determined radiometrica

ISSN:0021-8871    

DOI:10.1002/jctb.5010190102

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractAn automated version of the Fraass brittle‐point test has been constructed which gives easier operation and better reproducibility than either an earlier modification or the original test.The brittle‐point data for road tars have been shown to vary linearly with the equiviscous temperature of the materials. The use of the test to study the modification of road tar is illustrated, and it is proposed for the examination of the effects of weather

ISSN:0021-8871    

DOI:10.1002/jctb.5010190103

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractIn the recovery of plutonium from high‐fired uranium‐plutonium oxides dissolution is the most critical step. It has been found that 100% solid solutions of uranium‐plutonium oxides are readily soluble in 14 m nitric acid. A procedure has been developed to convert any mixed oxide completely into a solid solution, so that dissolution is faster than the usual direct dissolution in nitric acid‐hydrofluoric acid. The use of the latter acid is thus avoided. Nitrides and carbides are oxidised to oxides which are subsequently dissolved in pure concentrated nitric acid. Detailed procedures ar

ISSN:0021-8871    

DOI:10.1002/jctb.5010190104

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractSome samples of technical grade silica and titania on storage for several years at room temperature show loss of apparent surface. The loss is attributed to dehydration of surface hydroxy‐groups. This can cause adhesion and aggregation of particles whereby the surface measured both by nitrogen and by dyes decreases, and, in some cases, causes a loss of surface reactivity.With heating at temperatures up to 250°, the loss of apparent surface of silica is increased, but that of titania is partly restored. It is suggested that these effects may influence specific surface measurements made by vapour phase adsorption if high temperature out‐gassing is empl

ISSN:0021-8871    

DOI:10.1002/jctb.5010190105

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe distribution of sulphuric acid between water and 40% by vol. solutions of tri‐n‐butyl phosphate (TBP) in six diluents, and also between water and 40, 60 and 80° solutions of TBP in cyclohexane at 20°, and between water and 40% solution of TBP in cyclohexane and pure TBP at 20°, 30° and 50° has been studied to find the effects of temperature, diluent and TBP concentrations on the extractability of sulphuric acid and on ‘third‐phas

ISSN:0021-8871    

DOI:10.1002/jctb.5010190106

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractAmorphous silica influences tricalcium aluminate (C3A) hydration both in pastes and in suspensions.Two heat peaks are found by isothermal calorimetry during the paste hydration of C3A. The addition of amorphous silica causes the second heat peak to shift towards shorter reaction times and become more pronounced.In suspensions, the change in ion concentration in the water phase is not influenced by the presence of amorphous silica except that the change in concentration occurs more quickly. QuantitativeX‐ray analysis shows that more 3CaO.Al2O3.6H2O is present in suspensions containing amorphous silica than in silica‐free suspensions at equal hydration ti

ISSN:0021-8871    

DOI:10.1002/jctb.5010190107

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe ultra‐violet absorption, in the range 250 mμ—350 mμ, of twelve 4‐hydroxy coumarins in methanol and in 10% aqueous methanol over a range of pH, has been studied and di

ISSN:0021-8871    

DOI:10.1002/jctb.5010190108

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

ISSN:0021-8871    

DOI:10.1002/jctb.5010190109

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY