T o the Editor: The following may be said in reference to the article by C. D. Nenitzeseu (J. CHEM.EDUC.,34, 147 (1957)). Rather than the Wohl scheme confirming the Freudenberg system, it would seem that the opposite would be true. This may be seen by the following series of reactions, comprising both schemes:
T o the Editor: I am sorry that I did not include a description of the interpretation of the "Beating Heart Experiment" described in the March issue of the JOURNAL OF CHEMICAL EDUCATION (p. A105). Since there has been some interest in this experiment, I hope you will find it possible to include the following description in the
JOURNAL: The surface tension of mercury is a function of the electric charge on the liquid mercury. When the charge increases, the surface tension increases and the mercury tends to assume a more spherical shape. In the oxidizing medium where the mercury and the iron both find themselves, each is oxidized leaving some electrons on the solid iron and the liquid mercury. More charge is left on the iron due to its high reduction potential. When the iron touches the mercury, therefore, this charge is transferred electrically, the mercury gets a higher negative charge and tends to assume a spherical shape, that is, contract.. The oxidizing agent, dichromate ions, then removes the electric charge a t the mercury surface and the mercury again flattens out. When it does so, it comes in contact with the iron, thus becoming recharged,and goes into the cyclical or beating procedure which is observed.
T o the Editor: The discussion on the assignment of the D and L prefixes to the tartaric acids on the basis of the Wohl and the Freudenberg couvent,ions mas interesting (J. CHEM. EDUC.,March issue). I t would seem to lay the foundation for a decision one may or the other. It occurs to me that it is worth stressing that if the Wohl convention is used, then the prefix of D-malic acid as given by Abernathy should logically be changed to make it consistent with the bottom asymmetric carbon rnle also. I believe this is implicit in Abernethy's discussion, but it is not stressed.
I t would seem, then, that D-glyceraldehyde was equivalent to L-glyceraldehyde, What has happened is that conversion of the (-)-tartaric acid to glyceric acid has resulted in reversal of the positions of the primary alcohol and aldehyde groupings, while the hydroxyl of the secondary group remains projected to the right. It would be more logical, then, to equate the two hydroxyl gronps concerned before such a change has occurred, rather than after.
T o the &%tor: We wish to protest the treatment of our manuscript entitled, "Concentration Cells-A Simple Lecture Demonstration." At your suggestion we agreed that this contribution should be editorially shortened and included in the new series of "Tested Lecture Demonstrations." On March 29 we received, the first intimation, (a page proof) of the form which actually appeared in the April issue. This allowed no possibility of revision, and consequently we feel that an unchecked proof has been printed. Although the contribution is a minor one, we feel that we should have been given opportunity to make modifications. There is a serious omission from the material we submitted: The demonstration should commence with both electrodes in the same solution. This is to show that any e.m.f. later developed is due to differences in the environments of the electrodes and not to the electrodes themselves.
JOHN T . STOCK W I L L IC. ~ PURDY
JOURNAL OF CHEMICAL EDUCATION
