Reagents for the Van Slyke-Folch wet carbon combustion.

Van Slyke and Folch (1) used as a combustion mixture a solution of H&04, HsP04, and CrOa, to which pulverized KI03 was added in the combustion tube. It has been found advantageous instead to use as a fluid a mixture of H&S04 and HsPOa without CrOs, both KI03 and KzCrzOr being added in solid form in the combustion tube. This modification has the advantage that both the liquid and the solid reagents are stable (the original CrOrc solution weakened slowly on standing) and that manipulation of the caustic CrOa solution is avoided. Also, the modification outlined below, with increased KI03:K2Crz01 ratio, for carbohydrates and polyhydroxyl alcohols has yielded results more consistently approaching 100 per cent of theoretical with these substances.