INNER CRUCIBLE METHOD FOR DETERMINING SULPHUR AND HALOGENS IN ORGANIC SUBSTANCES
Journal of the American Chemical Society
carrying out the Blank and Finkenbeiner method has been adopted by the authors. It has been tested on a number of samples and has been found to always lead to safe, accurate results with the expenditure of a minimum amount of time and attention. jl/lethod.--Measure out 50 cc. of normal sodium hydroxide in a small Erlenmeyer flask (say of 500 cc. capacity) and add 50 cc. of pure 3 per cent. hydrogen peroxide. Now add from a pipette 3 cc. of the formaldehyde solution under examination (the
... ination (the specific gravity of which has been previously determined), allowing the point of the pipette to almost reach the liquid in the flask. Place a funnel in the neck of the flask and put on the steam-bath for five minutes, shakingoccasionally during this time. Remove from the steam-bath, wash the funnel with distilled water, cool the flask down to about room temperature and titrate the excess of sodium hydroxide with normal acid, using litmus as indicator. This cooling of the flask before titration with acid was found necessary so as to get a sharp end-reaction with the litmus. From the volume of formaldehyde used and the specific gravity, the percentage by weight of formaldehyde can be determined.