February i, 1894] 



NA rURE 



any special organs of vision, and yet that they were most active 

 creatures, and would catch such agile insects as Thysanuridse 

 without constructing any web or trap, and did not seem to suffer 

 in the least Irom their eyeless condition ; he had seen small and 

 weak Acari quietly waiting until larger ones had finished feeding 

 before they ventured to attack the leavings, although both were 

 blind. The various forms of acarine parasitism and commen- 

 sualism were then described, including one where a parasite 

 lives in the fur of the rabbit, not feeding on the host, but on 

 other parasites which really do so, and the number of these 

 which it will destroy is amazing. The President then illustrated 

 the principal families of Acari by selecting one or two instances 

 of each, which were specially interesting either from their habits, 

 their anatomy, or otherwise. The Sarcoptidse, or bird parasites, 

 were represented by a parasite of the cormorant, discovered by 

 the President, in which the male has one leg much larger than 

 the other, and the skeleton of the body is greatly modified to 

 support it ; but the enlarged leg and modified skeleton are on 

 the right side of the body in some specimens, and on the left in 

 others. The so-called cheese-mites were referred to in order to 

 describe the hypopus-stage in the life-history of many of them ; 

 when the creature, which is originally soft and easily killed by 

 heat or exposure, suddenly becomes hard and able to endure 

 almost all vicissitudes, and also to live for a long period without 

 eating : it is then provided with special organs for adhering to 

 insects, and thus the species are widely distributed under cir- 

 cumstances where they would otherwise perish. The President 

 then spoke of his recent res- arches into the association between 

 many Acari (Gamasids) and certain ants in whose nests they live, 

 and of a still stranger and hitherto unrecorded case, even 

 more lately observed by him, in which a species of Acarus 

 {Bdelia) lives habitually in as pider's web in harmony with the 

 otherwise most ferocious occupant. The speaker then shortly 

 described his recent discovery of the extraordmary way in which 

 female Gemasids are fertilised, a spermatic capsule being con- 

 veyed to its destination by the mandibles of the male. Finally, 

 the descent of the Acari was discussed. The discourse was 

 illustrated by the lantern. 



Edinburgh. 



Royal Society, December 12, 1893. — The Rev. Prof. Duns 

 in the chair. — Dr. George Berry read a note on the focus of 

 concavo-convex lenses, the surfaces of which are of equal curva- 

 ture. The effect of the thickness of the lens was specially con- 

 sidered. — Dr. W. Peddie read a paper on torsional oscillations 

 of wires. The law of decay of oscillations when the set is 

 large was investigated experimentally, and a very accurate em- 

 pirical formula was given for the representation of the results. 

 A theory of the phenomenon was then investigated, and was 

 shown to lead to the empirical formula as an approximation 

 when the loss of energy per oscillation was not too large a frac- 

 tion of the total energy of oscillation. The theory was also 

 shown to lead to a relation between torsion and set, which, on 

 application to Wiedemann's results, was found to be in practi- 

 cally complete accordance with experiment. It was shown also 

 to lead necessarily to Kelvin's well-known "law of compound- 

 interest " for the decay of oscillations when these are very 

 small. — Dr. C. G. Knott communicated a paper, by Mr. S. 

 Kimura, on certain electrical properties of iron occluding gases. 

 The gases used were carbonic acid, carbonic oxide, and hydro- 

 gen. The paper dealt with the changes of thermo-electric 

 power and of resistance. — Dr. Knott also read a paper, by Mr 

 S. Tolver Preston, on the ether — an idea of Sir John Herschtl 

 modernised. 



January 15. — Prof. Sir Douglas Maclagan, President, in the 

 chair. — After the reading of two obituary notices. Prof. Crum 

 Brown communicated a paper by Prof. Alexander Smith, Wa- 

 bash College, Indiana, U.S.A., on two stereo-isomeric hydra- 

 zones of benzoin. — Dr. Knott communicated a paper, by Prof. 

 Tait, on the compression of fluids. In this paper Amagat's 

 recently published results are applied to test the truth of the 

 empirical formula 



7J^-v _ e 

 c',,/ ir -f /' 



where ir is the internal pressure and v^{\-e) is the ultimate 

 volume under infinite pressure. Tests are made, at pressures of 

 I, 1501, and 3001 atmospheres, for the substances ether, ethylic 

 alcohol, methylic alcohol, propylic alcohol, carbon bisulphide, 

 iodide of ethyl, chloride of phosphorus, acetone, and water. 



The quantity e is found to be nearly the same for all these sub- 

 stances, and indicates an ultimate reduction of volume of about 

 30 per cenf. It increases as a rule with rise of temperature. In 

 the case of water, -k increases steadily with rise of temperature 

 up to about 40° C. In all other substances -k decreases steadily 

 with rise of temperature. These facts correspond to the known 

 changes of compressibility with temperature. An attempt is 

 then made to see how far it may be possible to extend the 

 formula to substances such as carbonic acid at ordinary tem- 

 peratures, considerable pressure being required to keep the sub- 

 stance in the liquid state. Consistent values of e and -k are 

 obtained at temperatures and pressures both above and below 

 the critical point. It is found that ir is positive, at volumes a 

 little above the critical volume, over a considerable range of 

 temperature. Hence the Laplace effect predominates over the 

 kinetic repulsion In the other regions for which tests were 

 made, -k is negative. It vanishes, at a temperature a little over 

 80° C, throughout the observed range of volumes. This vanish- 

 ing of TT corresponds to the case of the ideally perfect gas. 



Paris. 



Academy of Sciences, January 22. — M. Lcewy in the 

 chair. — Integration of the equation for sound in an indefinite 

 fluid in one, two, or three dimensions, when resistances of 

 various types introduce into this equation terms proportional 

 respectively to the characteristic function of the movement or 

 to its first derived partials, by M. J. Boussinesq. A solution 

 of a problem in the propagation of sound-waves suggested by 

 M. Poincare in a recent communication. — On the calculation of 

 coefficients of self-induction in a particular case, by M. A. 

 Potier. — Experiments on the histological mechanism of the 

 secretion of granular glands, by M. L. Ranvier. An account 

 of methods employed in observing the cell-activities of the sub- 

 maxillary gland of the rat, — A study of the fauna of the Gulf 

 of L>ons, by M. H. de Lacaze-Duthiers. — Report on the 

 meteorological observatory established by M. Vallot, near the 

 summit of Mont Blanc, and on the first volume of the annals of 

 the work of this oWservatory, by the commissioners, MM. 

 Mascart and Bouquet de la Grye. — On the solar phe- 

 nomena observed at the observatory of the Roman Col- 

 lege, during the first two quarters of the year 1893. 

 A letter by M. P. Tacchini, giving details concerning 

 protuberances, faculse, spots, and eruptions observed. 

 All the phenomena were more frequent in the southern zones, 

 the maximum numbers also were found in these zones. In the 

 first quarter, eruptions were not observed. The maxima of 

 faculse and spots were found in the same zones (± 10°, ± 20°), 

 of protuberances in higher latitudes. — Note on equations and 

 implicit functions, by M. A. Pellet. — On new ex- 

 perimental studies concerning the form, pressures, and 

 temperatures of a jet of vapour, by M H. Parenty. 

 Diagrams are given showing the distribution of pressures in 

 jets with apertures of different types. — Contribution to the 

 study of the properties of the arc with alternating current, by 

 M. G. Claude. — On the minimum electromotive force necessary 

 for the electrol>sis of dissolved alkaline salts, by M. C. Nourris- 

 son. From thermochemical data the E.M. F. necessary is for 

 chlorides 2'02 volts, ' romides 175, iodides i-i6, sulphates 2'15, 

 nitrates 2 07, and chlorates 2'07 volts. The experimental results 

 for the halogen salts of the alkalies and alkaline earths agree 

 with these numbers, but for the corresponding sulphates, 

 nitrates, and chlorates somewhat higher values are obtained. 

 The minimum E M.F. necessary for the electrolysis of a dis- 

 solved alkaline salt is constant lor oxy-salts and is constant for 

 the haloid salts of the same acid. — On an application of sodium 

 silicate, by M. G. Geisenheimer. The application referred to 

 is that ot being used to soften waters for laundry purposes. — On 

 some phosphochromates, by M. Maurice Blondel. The forma- 

 tion and pr perties are described of bodies having the formulas 

 3K2O.P2O38C1O3 and 2KoO.H20.P205.4Cr03, or 2K3PO4. 

 SCrOj and 2K2H PO4 4Cr03. — Action of sulphuric acid on 

 wood charcoal, by M. A. Verneuil Some of the secondary 

 products have been isolated and identified, notably the penta- 

 and hexa-carbo.\ylic acids, C6H(C02lI).5 and C6(C0oH)g. — Con- 

 densation of isovaleraldehyde with acetone, by MM. Ph. Barbier 

 and L. Bouveault. — Studies on the chemical properties of the 

 alcoholic extract of yeast ; formation of carbonic acid and ab- 

 sorption of oxygen, by M. J. de Rey-Pailhade. — On the sea 

 bottom of the region of Banyuls and Cape Creux, by M. G. 

 Pruvot. — A certain symptom of death, indicatedby the ophthal- 



NO, 1 266, VOL. 49] 



