K. P. Rippon, W. Vogel, W. Ramsden, L. R. Morris, M. S. Cresser, J. H. G. Knight and A. L. Gray, Proc. Soc. Anal. Chem., 1971, 8, 232 DOI: 10.1039/SA9710800232

The apparatus used in this work comprises a double photoinultiplier adapter of the variable wavelength type, designed primarily for basic research with quartz prism spectrographs, and an electrical integrator. Details of performance are given for electrical and for photometric measurements and the influence of movements of the light source is considered.

The effect of the intensity of the exciting radiation on the efficiency of zinc-sulphide phosphors activated with silver an d containing varying amounts of cobalt below 4·10−4 percent has been studied at temperatures between −180° and 100°C. The results are in agreement with the theory of hole migration and show that the rate of recombination of electrons with ionized killing centers is much faster than that of electrons with ionized silver centers. From the change of intensity dependence with temperature between 0 and 100°C the distance between the activator level and the full band was found to be 0.37 ev. To explain an anomalous result at low temperatures with high Co concentrations, it is suggested that shallow electron traps are present in the zinc-sulphide lattice.

IN an attempt to find out how the most available silkworm (larva of Bombyx mori) makes the insoluble fibroin strands of its silk from the stiff water-soluble fibroinogen paste which forms the cores of the contents of its silk depots, two of the observations made have so much general interest that I send a brief account of them in the hope that others will either contribute to their explanation or direct attention to corresponding phenomena in other cases.

IN a letter to NATURE of Nov. 1, p. 685, I stated that saturated aqueous solutions of urea unmasked a sulphide in sheep's wool and also extracted a sulphide from the wool. These two statements were based on the observation that addition of a tenth volume of 20 per cent sodium nitroprusside solution, to suspensions of wool in such urea solutions, ten minutes after addition of a similar proportion of 10 per cent potassium cyanide solution (to reduce any —SS— to thiol groups), always led to the development, both in the wool and in the liquid, of a strong pink or magenta colour precisely like that of Arnold's nitroprusside reaction for organic thiol compounds, although in control tests wool not treated with urea developed only a feeble pink, and urea solutions which had not been in contact with wool developed none at all.

THE important article by Sir Frederick G. Hopkins which appeared in NATURE on Aug. 30 and Sept. 6 records many valuable new observations on which he is to be congratulated. It has, indeed, only one defect, and, at his request, I write to make that good, namely, the absence of all reference to the observations made many years ago by myself and my delightful friend Dr. N. G. Chavasse, a man who was twice awarded the V.C., and whose loss is to me one of the major tragedies of the War. The fact that Sir Frederick knew nothing of these observations is, however, very intelligible, since the first paper (Jour. of Physiol., 28, pp. 23–26; 1902) appeared obscurely in the Proceedings, only, of the Society concerned, and the second (Proc. Faraday Soc., March 1913; German translation in Zeits. f. Kolloide, 12, pp. 250–252; 1913) was entitled “Graded Protein Sols”.

W. Ramsden, Trans. Faraday Soc., 1926, 22, 484 DOI: 10.1039/TF9262200484

LONDON. Royal Society, November 6.—Sir Archibald Geikie, K.C.B., president, in the chair.—Prof. E. W. MacBride: Studies in heredity. II., Further experiments in crossing the British species of sea-urchins. In this paper the results obtained two years ago and communicated to the society are confirmed and extended. The hybrid produced by fertilising the egg of Echinus with the sperm of Echino-cardium is described. This hybrid was not obtained two years ago. The effect of foreign sperm in producing cyto-lysis on an egg is described, and it is also shown that an egg may become totally unreceptive for foreign sperm, whilst it is still perfectly capable of being fertilised with the sperm of its own species.— A. D. Hall, W. E. Brenchley, and L. M. Underwood: The soil solution and the mineral constituents of the soil.—Prof. B. Moore and T. A. Webster: Synthesis by sunlight in relationship to the origin of life. Synthesis of formaldehyde from carbon dioxide and water by inorganic colloids acting as transformers of light energy.—Dr. B. Blacklock and Dr. W. Yorke: The trypanosomes causing dourine (mal de coït or Beschälseuche).—T. G. Brown: Postural and non-postural activities of the mid-brain.—J. O. W. Barratt: The nature of the coagulant of the venom of Echis carinatus.—E. H. Rodd: Morphological studies in the benzene series. IV., The crystalline form of sulphonates in relation to their molecular structure.— Prof. W. H. Bragg and W. L. Bragg: The structure of the diamond.—Hon. R. J. Strutt: Note on electric discharge phenomena in rotating silica bulbs.—J. N. Pring: The origin of thermal ionisation.—Clive Cuthbertson and Maude Cuthbertson: The refraction and dispersion of gaseous nitrogen peroxide.

In a paper published in Du Bois Reymond’s ‘Archiv für Anat. und Physiologie’ in 1894, I showed that mere agitation of various proteid solutions brought about a separation of some of their contained proteid in the form of fibrous or membrano-fibrous solids, and that it was possible in this way to coagulate and remove the whole of the proteid from solutions of egg-albumin. It was proved also that these de-solutions and coagulations of proteid were not due to the action of enzymes, heat, or surface evaporation, and were not appreciably affected by the nature of the gas in contact with the liquid or of the vessel in which the agitation was effected. A prolonged series of further experiments, undertaken with a view of ascertaining the precise cause of this phenomenon, has led me to the discovery of an important, but hitherto unnoticed physical fact:—namely, that, quite apart from evaporation, solid or highly viscous coatings are spontaneously, and more or less rapidly formed on the free surfaces of all proteid solutions.