摘要:

In the survey of Alberta waters in which fluorine content is compared with the prevalence of mottled teeth, the titration method and the colorimetric method for determining fluorine have not always given comparable results. Good results with the titration method are obtained when distillation is carried out with perchloric acid instead of with sulphuric acid. It was found that the colorimetric method is affected by more than 2 p.p.m. of phosphate, aluminium, or ferric ions, and by over 120 p.p.m. of sulphate ions. Moderate amounts of manganous, ferrous, silicate, chloride, and sodium ions do not interfere. When the water contains over 2 p.p.m. of phosphate, aluminium, or ferric ions, or if the water is coloured, the titration method is used. A scheme for correcting for sulphate ions is proposed. The titration method and the colorimetric method used in this laboratory for determining fluorine in waters are given in detail.

ISSN:1923-4287    

DOI:10.1139/cjr40b-020

出版商:NRC Research Press    

年代:1940

数据来源: NRC

摘要:

not available

ISSN:1923-4287    

DOI:10.1139/cjr40b-021

出版商:NRC Research Press    

年代:1940

数据来源: NRC

摘要:

The heats of adsorption and wetting by aqueous sodium hydroxide, water, and methyl alcohol have been determined for celluloses mercerized at several different alkali concentrations. A quantity named the "heat of mercerization" has been determined, and it is considered to be a measure of the irreversible effects that distinguish mercerized from standard cotton cellulose, such as changed crystal lattice and enhanced internal surface. The extent of the latter change for the various mercerized celluloses has been shown by the heat of wetting measurements with water and methyl alcohol.

ISSN:1923-4287    

DOI:10.1139/cjr40b-022

出版商:NRC Research Press    

年代:1940

数据来源: NRC