A Modified Burette for Standard Alkali Solutions

Paul Rudnick
1910 Journal of the American Chemical Society  
A Modified Burette for Standard Alkali Solutions.-Glass stoppered burettes offer serious obstacles to their constant employment for standard solutions of caustic alkalis. The tendency of the stopcock to stick, rapid wear, resulting in leakage, or breaking of the cock or of the shell, and other difficulties constitute serious objections to this form of burette for caustic alkali solutions. The type of burette in which a glass tip is connected to the burette by means of a rubber tube, the flow
more » ... ng controlled by a pinchcock or a glass ball, is an alternative which is still in considerable use, but the objection to this type on the ground of inaccuracy is well understood, and the United States Bureau of Standards will not calibrate such burettes. It occurred to the writer that the substitution of metal for glass for the movable part of the stopcock might overcome the difficulty and that of the metals adapted to this purpose, silver might perhaps be preferable both because of its fairly good resisting powers towards caustic alkali, as well as on the ground of reasonable cost. Accordingly, a burette fitted with a silver stopcock was tried by filling with half-normal potassium hydroxide solution and allowing to stand for a week. The stopcock did not show the slightest sign of sticking or leakage. The burette was then emptied and filled with 30 per cent. sodium hydroxide solution and in the course of several weeks the stopcock was operated several times nearly every day.
doi:10.1021/ja01926a014 fatcat:5l2qvj56lbb5lmpmsbnd2mknbi