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WE have recently developed a simple method for quantitative assay of amino-acids on the paper partition chromatogram. The method is in all probability applicable to any class of substance which can be readily located by means of a sensitive colourreaction on paper. Several technical points of general interest have arisen in the course of the work.

PROTEIN tagged with radioactive iodine (iodine-131) is proving useful in immunological research because of its ready detectability1. Also the firm substitution of the iodine in the tyrosine molecule renders conclusions based on the occurrence of radioactivity in the tissues more acceptable as evidence of the presence of the antigen or its partial breakdown products than has been the case with arsenic and dye tracers2. The application of various methods including paper chromatography to the study of the fate of iodinated antigens has produced results which appear of general interest.

WE have read with interest the letter of M. Lederer on the paper chromatography of the noble metals1, especially as it appeared so soon after our own communication2 on inorganic chromatography. We have been engaged in a general study of this subject for the past two years3, and our results will be published in detail separately. In view, however, of Dr. Lederer‘s letter and the general interest which has been aroused by our preliminary communications2,4, we give below some supplementary information which may be of value.

ONE of the Notes in NATURE of November 25 (p. 351) begins with the following sentence:—“The theory that the upper layers of the atmosphere are ionised and therefore conduct electricity, first enunciated by the late Prof. FitzGerald in 1893,...” It is a good rule, to which I have always hitherto adhered, not to raise questions of priority, but in this particular case a point of general interest in scientific history is involved, and a claim made which postpones the enunciation of a fruitful idea by six years. In the paper presented to the Royal Society in May, 1887 (Proc. Roy. Soc., vol. xlii., p. 371), I proved by experiment that the gas in a vessel through which an electric discharge passed became a conductor even in regions of the vessel remote from the discharge, and at the end of the paper the application of this result to the conductivity of the regions of the atmosphere affected by thunderstorms and aurorae is quite clearly expressed.

LAST year we reported the details of a method by which it is possible to determine the “strone and “striol content of human pregnancy urine colorimetrically with a reasonable degree of accuracy1. Since the publication of our paper we have received numerous inquiries as to whether the method can be used for the determination of the “strin content of urine of non-pregnant women. As this question seems to be one of some general interest, and since in our paper we made no mention of the possibility of using our method for this purpose, we wish to take this opportunity of mentioning briefly our views on the matter.

THE German Zoological Society consists of about 240 experts, who meet in variable numbers for two or three days annually in some happily chosen hospitable spot, where they hold high discourse. There were only about sixty members present at last summer's (twelfth) meeting in Giessen, but the Society, if not large in numbers, is strong in quality. It is not pecuniarily rich, for it has backed out of more than an honorary responsibility witH regard to one of its offspring—an expensive child—“Das Tierreich,” which the Berlin Academy of Science will henceforth solely foster, but it is rich in enthusiasm, as we infer from the proposal to segregate into entomological, ornithological and other sections. Long may it live and thrive, and continue to publish its interesting proceedings, which we have just been enjoying. The volume, ably edited by Prof. Korschelt, contains a general introductory address by Prof. Chun; a welcome from Prof. Hansen, as rector of the University of Giessen; a short reminiscence, by Prof. Spengel, of the zoologists who have taught and wrought at Giessen, e.g. Leuckart, Schneider and Ludwig; and;about sixteen papers, most of which impress us with their general interest, their lucidity and their brevity. Verhandlungen der deutschen zoologischen Gesellschaft, xii. Versammlung, Giessen, 1902. Pp. iv + 221. (Leipzig: Engelmann, 1902.)

THE interesting results on partial reaction of the monolayer quoted by Dobry and Mahncke are of general interest and do in fact support the earlier observations of Bowden and Moore1. Even allowing for the factor of 4, they found that with copper surfaces immersed in a benzene solution of stearic acid the initial reaction was very slow, and after an immersion time of 5 min. considerably less than a single monolayer of soap was formed (see their paper, footnote p. 904). After prolonged immersion, chemical attack was quite heavy and corresponded to the reaction of several molecular layers. Results of this type obtained with layers adsorbed from solution are probably more significant than those obtained with layers deposited from the Langmuir trough. The latter are often unstable and tend to collapse; they appear to form bridges over the surface irregularities so that the area of molecular contact may be considerably smaller than the area of coverage. With layers adsorbed from solution this is not so, though as Daniel2 and Hirst and Lancaster3 have pointed out, dilute solutions themselves may give less than a complete adsorbed monolayer.

IN a letter to NATURE1, Chievitz and Hevesy made a provisional communication on the use of radio active indicators in the study of phosphorus metabolism in rats. In a recent paper to the Royal Society of Copenhagen2, a detailed account of these investigations was given. Since 1936, we have been making experiments on phosphorus metabolism in normal, rachitic and treated rats, utilizing also a radioactive phosphorus isotope as an indicator3. Although the detailed figures will be published shortly in the Proceedings of the Royal Academy at Amsterdam, we think a brief review into our experiments may be of general interest.