yune 17, 1875J 



NATURE 



139 



lated and reprinted from othtr serials, besides several original 

 ones. We note the following :— On the fossil vertebrata of the 

 State of Nebraska, by M. Delafontaine. On the measurement 

 of altitufles in Switzerland, executed by MM. Hirsch and Planta- 

 mour. On the action of galvanic currents upon alloys or amalgama, 

 by M. Eugene Obach. On some experiments with Hollz's 

 machine, by F. Rossetti. Researches on the spectrum of chloro- 

 phyll, by J. Cbautard. 



SOCIETIES AND ACADEMIES 



London 

 Linnean Society, June 3.— Dr. G. J. Allman, F.RS , 

 president, in the chair.— The President rommated the fol- 

 lowinc pentlemen as Vice-presidents for the ensuing year, 

 viz. :-^Mr. G. Bentham, F.R.S. ; Mr. G. Busk, F.R.S. ; 

 Dr. J. G. Jeffreys, F.R.S. ; and Dr. J. D. Hooker, P.R.S.— 

 Prof. Thiselton Dyer exhibited, under the microscope, some 

 specimens of the very rare Alga Stephanosphara pluvialis, known 

 to occur only in a single locality in Britain, a pool on Bray 

 Head, in Ireland.— Dr. Trimen exhibited specimers of two 

 recert additions to the British flora, Zannickellia polycarpa, 

 found by Dr. Boswell-Syme in the Orkney Islands in 1847, and 

 Carex ornii/iopoda, discovered by two working men in Derby- 

 shire.— Mr. Pascoe exhibited a very fine collection of Crustacea 

 from the Bay of Naples. The following papers were then 

 read :— On the Barringtoniaceos, by J. Miers, F.R.S. The pur- 

 pose of this paper is to show that the Barringtoniaceas consti- 

 tute a distinct order, forming an extremely natural group with 

 peculiar and uniform characters, differing from the Myrtaceaj in 

 their alternate leaves without pellucid dots, and in the nature of 

 their inflorescence and fruit. They are trees, frequently of 

 large size, rarely low shrubs, all delighting in running 

 streams, some growing in estuaries or along the sea-shore. 

 The author describes the characters of the order in consi- 

 derable detail, and gives the diagnosis— in many cases re- 

 drawn from actual examination — of each genus and species. 

 The number of genera he makes to be ten. The paper was 

 accompanied with drawings illustrating the floral and car- 

 pological characters of each genus.— Note on the occurrence 

 of fairy rings, by Dr. J. H. Gilbert, F.R.S. This paper 

 was founded on the observations made by the author and 

 Mr. Lawes on their experimental plots at Rothamstead. 

 After some particulars as to the effect of different manures 

 in varying the proportion of different kinds of vegetation 

 in permanent pasture, especially grasses and Leguminosa?, the 

 author suggests that the determination of the source of the nitro- 

 gen in the fungi that constitute the fairy rings which frequently 

 make their appearance on the plots would throw some light on 

 the much-disputed question of the source of the nitrogen of the 

 Leguminos^. It is remarkable that although, according to 

 published analyses of various fungi, from one-fourth to one-t*.ird 

 of their dry substance consists of albuminoids or nitrogenous 

 matter, and 8 to 10 per cent, of mineral matters or ash, of which 

 about 80 per cent, is potassium phosphate ; yet the fungi develop 

 into "fairy rings" only on the plots poorest in nitrogen and 

 poorest in potash. The questions which appear still to require 

 solution are these :— (i) Is the greater prevalence of fungi under 

 such circumstances due to the manurial conditions themselves 

 being directly favourable to their growth? or (2) Are the lower 

 orders of plants— in consequence of other plants and especially 

 grasses growing so sluggishly under such conditions — better able 

 to overcome the competition and to assert themselves ? (3) Do 

 the fungi prevail simply in virtue of the absence of adverse and 

 vigorous competition, or to a greater or less extent as parasies, 

 and so at the expense of the sluggish underground growth of the 

 plants in association with them ? or (4) Have these plants the 

 power of assimilating nitrogen in some form from the atmo- 

 sphere ; or in some form or condition of distribution within the 

 soil, not available, at least when in competition, to the plants 

 growing in association with them ?— On a possibly wild form 

 of hibiscus Kosa-sinensis, by Prof. Oliver, F.R. S. 



Mathematical Society, June 10.— Prof. II. J. S. Smith, 

 F.R.S., president, in the chair.— Prof. Cayley, F.R.S., made a 

 brief communication on some figures of airves in 3-bar motion. 



Prof. Sylvester, F.R.S., spoke on "James Watt's parallel 



motion," and on an apparatus for regulating the motion of a 

 train of prisms.— Mr. T. Cotterill read a paper on the correspon- 

 dence of points coUinear with a fixed origin. In the paper S 



and yare taken homogeneous functions of any number of vari- 

 ables (say three, x y z): the degree of S being one lower than 

 that of 7] and are supposed to be connected with another set, 

 x' y z', of the same number of variables by the equations 



:! = I = --!^. If the variables x y z, x' y' z", denote the co- 

 X V T 



ordinates of two points in a plane, a correspondence is established 

 between them depending on the forms of S and T. The object 

 of the paper is to explain the relations between the corresponding 

 curves and to give examples. 



Physical Society, June 12.— Prof. Gladstone, F.R.S., pre- 

 sident, in the chair. — Lord Lindsay, Sir W. Thomson, and Prof. 

 Sylvester were elected members. — Mr. Wildman Whitehouse 

 described some experiments he had made on the electric conduc- 

 tivity of glass. He employed pieces of thermometer tube about 

 an inch in length, into the bore of which two platinum wires 

 were inserted in such a manner that there was an interval between 

 the points. In some casts one wire of platinum occupied the 

 entire bore of the tube, and this tube was surrounded on its 

 external surface by a helix of wire of the same metal. In each 

 case the arrangement was introduced into a circuit in which were 

 also placed a Thomson galvanometer and a set of resistance coils. 

 It was shown that at the ordinary temperature there was no deflec- 

 tion, but that the current passed freely when the glass was heated 

 to redness. The difficulty of making contact with the glass led 

 Mr. Whitehouse to use two test-tubes, one inside the other, both 

 containing mercury, with which wires of platinum freely commu- 

 nicated. The flame of a Bunsen burner was applied to the outer 

 test-tube and the temperature of the metal noted by the aid of a 

 thermometer. In one series of experiments the diameter of the 

 internal tube was | inch, the length in contact with the mercury 

 about 3I inches, and the thickness of the glass yjjjlh of an inch. 

 A current was first observed to pass at 100° C, and, as the tempe- 

 rature rose, the amount of deflection increased. The following 

 are approximate measurements of the resistance of the glass at 

 different temperatures : — 



At 165° C. Resistance = 229,500 Ohmads 

 ,, 185 ,, ,, = 100,000 ,, 



,, 210 ,, ,, = 69,000 ,, 



„ 255 „ „ = 22,500 ,, 



,, 270 ,, ,, = 9,000 ,, 



,, 300 ,, ,, = 6,800 ,, 



Prof. Gladstone drew attention to the necessity for ascertaining 

 the nature and composition of the glass. — Prof. Guthrie alluded 

 to the fact that electricity of high tension is freely conducted by 

 glass at a red heat. He also asked whether, as the temperature 

 was raised, a point was reached at which the conductivity began 

 to decrease.— Prof. M'Leod pointed out that the thermometer 

 tubes used by Mr. Whitehouse were of lead glass, and that 

 the lead had in most cases been reduced by exposure to the 

 flame of the Bunsen burner, and he urged that these facts should 

 not be overlooked in measuring the resistances. He stated that 

 lead glass is better than other kinds ot glass for insulation. — 

 Prof. G. C. Foster asked whether an increased capacity due to the 

 heating might not introduce an error into the measurements of 

 resistance. Mr. Whitehouse replied that he had only recently 

 commenced the experiments, and promised that the sugnesiions 

 which had been made should receive due attention. — The Pre- 

 sident then read a paper on the time required for double decom- 

 position of salts. It is well known that if, on mixing solutions 

 of two salts, MJi and A/'J\', an insoluble body can be produced 

 by an inteichange of metals and radicals, that body is produced 

 to the fullest extent possible. The only explanation of this fact 

 which has been given is founded on the theory of Bertholet, that 

 in all cases of mixture there is a redistribution of the constituents 

 according to their relative affinity and mass, with the production 

 of more or less A^A" and A/'J^. Now, if one of these, say MA", 

 be insoluble, it will remove itself at once from the sphere of 

 action, but this will necessitate a fresh distribution of the consti- 

 tuents with the production of more insoluble salt, and so on until 

 the whole of the A/ has entered into combination with A". Dr. 

 Gladstone commenced this research twenty years ago, and added 

 in a note to a paper in the Phil. Trans. : " It is easily conceivable 

 that when the affinity for each other of the two substances ihat 

 produce the insoluble compound is very weak, the action may 

 last some time and become evident to our senses. Is not this 

 actually the case when sulphate of lime in solution is added to 

 nitrate of strontia, or carbonate of soda to chloride of calcium, 

 or an alkaline carbonate to tartrate of yttria, or oxalate of 



