Vol. 70 tween 3000 and 2100 A. than that for the phenylhydrazine part of the molecule. This characteristic is exhibited, however, by several of the DNPH's prepared from apricot sirup, and suggests the possibility that it is common to a group of substances not represented in studies of known compounds. It is well known that alcoholic DNPH solutions change color from yellow to red or from yellow to blue when they are made alkaline. The resultant color has been used as the basis for colorimetric analytical methods in a number of cases. The results of work reported in this paper indicate a correlation between the color of DNPH's in alkaline ethanol solution and the degree of adsorption on magnesium sulfate. Furthermore, wide "phenylhydrazine adsorption" bands seem to be associated with compounds which give a blue color change in alkaline alcohol. These properties may be characteristic of a particular type of DNPH. The formation of a red color in alkaline ethanol is characteristic of simple aldehyde and ketone dinitrophenylhydrazones, while the formation of blue colors is associated with 2,4-dinitrophenylhydrazine derivatives such as bis-hydrazones which form with compounds such as sugar osones, glyoxal, diacetyl and methyl glyoxal.13 It is (13) Neuberg and Strauss, Arch. Biochent., 11, 457 (1946); 7. 211 (1945).not to be assumed that only bis-hydrazones give blue colors in alkaline ethanol solutions, but the fact that the blue color change is associated with bis-hydrazones and osazones is of special interest in view of the fact that apricots contain high concentrations of sugars. The possibility that sugar derivatives may be among these unknowns should not be overlooked.