In the preceding paper by GORTNER and HOFFMAN2 it was pointed out that studies of the physico-chemical properties of plant saps which include only measurements of the osmotic pressure, electrical conductivity, and H-ion concentration, leave out of account the very important influence on physical properties exerted by sap colloids. By the introduction of the refractometer as a part of the field laboratory equipment, these workers have shown it possible to make rapid and accurate determinations of the moisture content of the plant saps. Utilizing the additional data thus made available, a simple method has been devised which appears to give a relative measure of the content of hydrophilic colloids. The freezing point depression of the freshly expressed plant juice is first obtained. Then, having determined the total solids 3 SCATCHARD, G., The hydration of sucrose in water solution as calculated from vapor-pressure measurements. Jour. Amer. Chem. Soc. 43:2406-2418. I92I.

It has been shown that M-butyllithium dimetalates 9-phenylcarbazole homonuclearly to give, subsequent to earbonation and hydrolysis, 9-(2',-6'-dicarboxyphenyl)-carbazole. The structure of this dibasic acid was established by cyclodehydration reactions. Some experiments concerned with resolution studies of cyclodehydration derivatives are described.

In 1922 Newton and Gortner (1) put forward the hypothesis that at least a portion of the water associated with the hydrophilic colloids in plant tissues was in a "bound" form, in which form it exhibited physicochemical properties which would serve to differentiate it from the "free" water of the vacuolar sap. It was suggested that bound water might be unavailable for the solution of sucrose and accordingly a method for the estimation of such bound water was proposed which consisted essentially in first determining the freezing point of the solution which contained the hydrophilic colloid and denoting this value as A. An amount of the sol was then taken which contained exactly 10 gin. of total water. To this portion there was added 0.01 mole of sucrose and a second depression of the freezing point, designated Aa, was determined. If all of the 10 gin. of water were free to dissolve sucrose ha should differ from A by the freezing point depression of a molar solution of sucrose which according to Satchard (2) should be 2.085 °, corresponding to a gram molecule of sucrose-hexahydrate dissolved in 892 gm. of water.The formula which Newton and Gortner proposed Aa --(Zx -b Kin) percentage of bound water ---X 89.2 (1) Aa --A was tested by them on aqueous solutions of gum acacia and on certain plant saps and appreciable amounts of bound water were apparently demonstrated to be present. This method has been extensively used by numerous plant physiologists-especially Newton and his coworkers (3-6)--and has

No abstract

No abstract

Freundlich's observations (5) indicated a general relationship between adsorption and solubility and an apparent parallelism between surface tension lowering and extent of adsorption. Langmuir (20,21) and Harkins (14 to 17) developed independently the idea of molecular orientation, first suggested by Hardy (11 to 13), and gave a definite picture of the arrangement of solute molecules at interfaces. Still later, in investigating the mechanism of bacterial action, Quastel and his coworkers came to the conclusion that there are certain active centers "characterized by the possession of particular groupings which are able to adsorb a particular type of structure. A relatively large number of substances can be adsorbed in this specific manner, but out of this number only a few can be activated to act as hydrogen donators" (36). This work demonstrates the importance of molecular structure in specific adsorption.The literature, although it shows the importance of chemical configuration in adsorption phenomena, reveals no adequate study of several structurally related compounds on a single interface over any concentration range or any reasonable basis for comparison. This study was accordingly undertaken to compare the influence of certain groupings in typical organic acids on the adsorption of these compounds from aqueous solution within definite concentration ranges, using a single and comparable interface.1 Paper No. 1291, Journal Series, Minnesota Agricultural Experiment Station. Greatly condensed from a thesis presented by E. R. Linner to the Graduate School of the University of Minnesota in partial fulfillment of the requirements for the degree of Doctor of Philosophy, June, 1934. The detailed tabular experimental data are all included in a manuscript copy on file.in the Library of the University of Minnesota. Photostatic copies of the detailed tables may be obtained approximately at cost from the University of Minnesota.

No abstract

No abstract