Jan. i, 1885] 



NA TUBE 



pointed out that the analogy, as usually drawn between heat 

 ricity, namely, to liken temperature* to potential and 



quantity of heat to quantity of electricity, is not the true analogy, 

 inasmuch as the product of temperature and quantity of heat is 

 DOl of the nature of energy, and that the true analogue of quan- 

 tity of electricity is quantity of entropy. In this case a non- 

 conductor of electricity is a non-conductor of entropy, i.e. a 

 non-conductor of heat. As the quantity of electricity is the 

 same at all parts of a circuit, and as it requires a perfect heat- 

 engine to transfer entropy from one temperature to another un- 

 diminished, conductors must be of the nature of perfect heat- 

 engines. It was further pointed out that a molecular structure 

 of ether similar to that of a gas could be assumed, the motions 

 of whose molecules might be polarised in such a way by differ- 

 ences of temperature that, although no heat was conducted, it 

 would be thrown into a state of stress which would explain 

 electrostatic phenomena. It was explained that this was a step 

 beyond that made by Maxwell in his " Electricity and Mag- 

 netism," where he avoids any hypothesis as to how electric 

 displacement pro luces mechanical stress. The author stated, 

 however, that the object of this communication was not to bring 

 Forward this doubtful hypothesis, but, by drawing attention to 

 this analogy between heat and electricity, to prevent the danger 

 at present imminent "f it< being supposed that the analogy be- 

 tween electric displacements and the motions of an incompres- 

 sible fluid is the only analogy possible, and of this mere analogy- 

 being consequently mistaken for a likeness. — Howard Grubb, 

 chibited a star map photographed by the Rev. T. E. 

 lispin. 



Natural Science Section. — V. Hall, F.R.S., in the chair. — 

 1 >n a new species of Halcampa. This is the first recorded ex- 

 ample of the genus in Ireland, and it proves to be a new species, 

 tor which the name H. Andresii is proposed. It was found at 

 Malahide, Co. Dublin. — Mr. G. Y. Dixon exhibited a living 

 and some preserved specimens of Peachia haslata from Dolly- 

 mount Strand, Dublin Bay. This is the first Irish locality. — 

 The Chairman exhibited geological maps of Canada and of 

 the United States, with specimens of Lanrentian rocks and 

 minerals. 



Paris 



Academy of Sciences, December 22, 1884. — M. Rolland, 

 President, in -the chair. — On a new method of measuring 

 the heat of combustion of carbon and organic compounds, 

 by MM. Berthelot and Vieille. The present paper is limited 

 to the determination of the heat of combustion for cellu- 

 lose (coton) and the various carbons used in the manufacture of 

 gunpowder. — Description of a microscopic element by means of 

 which it may be possible to determine the various groups of 

 Cynthiada?, by M. de Lacaze-Duthiers. — Remarks on the 

 " Cours d'exploitation des Mines," presented to the Academy 

 by M. Haton de la Goupilliere. — Remarks on the volume of the 

 Connaissaanci Jcs Temps pour 1886 and the Annucdre pour 

 188S1 presented to the Academy in the name of the Bureau of 

 Longitudes by M. Faye. — Note on the indeterminate equation 



jfl - Kf = z», 



by M. Maurice d'Ocagne. — On the thermodynamic potential 

 and the theory of the voltaic pile, by M. P. Duhem. — Descrip- 

 tion of a diffusion photometer, by M. A. Crova. — Note on the 

 heat of combustion of the ethers of some acids of the fatty 

 series, by M. W. Louguinine. The author's experiments lead 

 to the general conclusion that the heat of combustion of an acid 

 is perceptibly equal to that of the ether of the same acid, less 

 the heat of combustion of the corresponding alcohol, regard 

 being had to the number of molecules of alcohol in reaction. — 

 Note on the a-ethylamidopropionic acid, by M. E. Duvillier. — 

 Observations on the optic activity of cellulose in connection with 

 i. Bechamp's recent communication, by M. Alf. Levallois 

 — On the cutaneous anaesthetic action of the hydrochlo- 

 rate of cocaine, by M. J. Grasset. It is shown that the 

 hypodermic injection of o'oi gr. of the hydrochlorate of 

 cocaine produces in man a sharply limited zone of cutaneous 

 anaesthesis without general phenomena, and with slight 

 local consequences, although lasting long enough to per- 

 form a certain number of surgical operations. — Influence of 

 the variations in the centesimal composition of the air on the 

 intensity of the respiratory functions, by M. L. Fredericq. — On 

 the spinal bone in the series of vertebrate animals, by M. A. 

 Lavocat. — Note on the constitution of the reticulate rhizopods, 



by M. de Folin. — On the Acari dwelling in the quill of 

 birds' feathers, by M. E. L. Trouessart. — On the existence of 

 phanerogamous Asterophyllites, by MM. B. Renault and R. 

 Zeiller. — On the Kersanton formation in the Croisic district, 

 Loire Inferieure, by M. Stan. Meunier. — On a phenomenon of 

 crystallogeny in connection with the fluorine of the Cornet rock 

 near Pontigabaud, Puy-de-D6me, by M. F. Gonnard — Results 

 of the analysis of the masses of boiled beetroot, made with a 

 view to determining the quantity of chloride of potassium and 

 nitrate of potassium contained in it, communicated by M. H. 

 Lepley. The quantity of these salts in 100 kilogrammes of root 

 was found to be : — 



Max. Mia. Mean. 

 [Gr. Gr. Gr. 



Nitrate of potassium 342 43 131 



Chloride of potassium 217 65 143 



Berlin 

 Physical Society, Nov. 21, 1884. — Prof. Neesen reported 

 on a case of magnetisation produced by a stroke of lightning, 

 the distribution of which had been examined by a former pupil 

 of the speaker. The lightning had struck the clock of a church 

 tower, and so strongly magnetised it that it was only by great 

 force that the pendulum could be moved from its position of 

 rest, while the clock had to be taken to pieces and the mag- 

 netised iron parts demagnetised by means of heat. The most 

 strongly-magnetic part was a U-shaped piece of cast-iron, the 

 two perpendicular and downward-directed legs of which bore 

 the edges for the pendulum. The distribution of the magnetism 

 in this piece of iron was as follows : — Not far from the lower 

 ends (at about a third of the height) was a neutral paint on both 

 sides, the inferior piece on one side being north polar, on the 

 other side south polar. On the side having the north pole, 

 south polar magnetism was found above the neutral point, 

 extending above the middle line and beyond, so as to take in 

 about the upper third of the other leg. Thereupon followed an 

 upper neutral point, between which and the lower neutral point 

 of this side was found north polar magnetism. The two lower 

 neutral points were the spots where the two legs of the U-shaped 

 piece of iron were connected by a horizontal iron pin. Other 

 effects of the lightning were not to be found either in the clock 

 or on the church tower. — Prof. Neesen further produced a 

 galvano-plastic high relief of iron, of a dull silver-gray, which in 

 fineness of detail far surpassed the productions of the silver 

 galvano-plastic art. The method by which this was produced 

 was still kept secret by the manufacturer. — Prof. Lampe com- 

 municated some interesting results arrived at by his pupils in 

 exercises in calculation. One problem was to calculate the 

 attraction of a homogeneous mass of certain form on a material 

 point of its surface, if the attraction of the same mass in globular 

 form on the pole was equal to 1. The calculation was first 

 made for a flattened ellipsoid, in which the attraction on the 

 polar point was known to be greater than I. With increase of 

 oblateness the attraction increased up to a maximum, for which 

 the magnitude of the attraction and the eccentricity of the 

 meridian curves were calculated. After this maximum the 

 attraction abated, with further increase of oblateness, and the 

 eccentricities of those meridian curves were calculated for 

 which the attraction was equal to 1, as also of those for 

 which it was equal to o'S. Similar calculations were made 

 for the elongated ellipsoid. In this case the attractions on the 

 polar point became continually less, and only the eccentricity 

 of the meridians was calculated, in which the attraction was 

 equal to 0-5. Another exercise was to calculate the attraction 

 of a circular cylinder on the middle point of a terminal plane, 

 when the relation of the radius, r, of the terminal plane to the 

 height, /;, changed. In this case, too, with a certain relation of 

 k to r a maximum of attraction was found, which was more than 

 I but yet less than the maximum in the case of the flattened 

 ellipsoid. After this maximum the attraction declined as well 

 with increasing h as with increasing r, and the two relations of 

 h to >-, in which the attraction was equal to 1, were found. 

 Finally, in the case of the circular cones, the attraction on the 

 apex was calculated, and here, too, the maximum was deter- 

 mined, being, however, less than 1, and the cone was determined 

 in which the attraction on the apex was equal to the attraction 

 on the centre of the fundamental plane. — Prof. Landolt described 

 a simple contrivance used by him for recovering the products of 

 sublimation. A test tube, of glass in the case of bodies 

 easy to sublime, of platinum in the case of bodies difficult to 



