ii8 



NATURE 



\Dec, 9, 



SOCIETIES AND ACADEMIES 



London 



Royal Society, Nov. 25. — " On the Replacement of Elec- 

 tro-positive by Electro-negative Metals in a Voltaic Cell," by 

 J. H. Gladstone, Ph.D., F.R.S., Fullerian Professor of Che- 

 mistry in the Royal Institution, and Mr. Alfred Tribe, Lecturer 

 on Chemistry in Dulw^ich College. 



It is well known that one metal exerts a greater chemical 

 force than another, and is capable of displacing it from its com- 

 binations. Among those metals with which we are familiar, 

 potassium is looked upon as the most powerful ; and it is a cer- 

 tain fact that calcium, barium, strontium, aluminium, and mag- 

 nesium have been isolated by its agency. It could scarcely be 

 expected, therefore, that any other metal could directly replace 

 potassium. If such should happen, we should have an instance 

 of reversal, and should expect to find, on examination of the 

 conditions, an agent capable of doing just the reverse work of 

 what is usually assigned to affinity. 



It is also well known that in a simple voltaic cell, such as zinc 

 connected with platinum in dilute hydrochloric acid, the more 

 powerful or electro-positive metal, zinc, displaces the hydrogen 

 that is in combination with chlorine, and the hydrogen makes its 

 appearance against the less powerful or electro-negative metal, 

 platinum. The chemical theory of galvanism supposes that the 

 force originates in the chemical action which takes place between 

 the zinc and the acid ; the contact theory supposes that it ori- 

 ginates in some unexplained manner in the opposite electrical 

 condition of the two metals induced by their contact. If the 

 chemical theory be the true one, it is evident that a zinc-platinum 

 cell can only become active when the binary liquid contains 

 hydrogen or some metal which is less powerful than zinc. If, 

 for instance, we were to employ a potassium-salt instead of a 

 hydrogen compound, it is inconceivable, on the pure chemical 

 theory, that there should be any action at all. 



Such an action, however, does take place if we substitute the 

 chloride of potassium for the hydrochloric acid ; the zinc com- 

 bines with the chlorine, and the potassium is set free in some 

 form against the platinum, manifesting itself by the presence of 

 free alkali and hydrogen gas. The same holds good with chlo- 

 ride of sodium, or ammonium, or barium, strontium, calcium, or 

 magnesium. 



This action is slow ; but if magnesium be used instead of zinc, 

 it takes place sufficiently rapidly to be easily observed, and we 

 have therefore studied the action of platinum and magnesium in 

 connection. 



After an account of the experiments, the paper concludes as 

 follows : — 



If one metal in conjunction with another more electro-nega- 

 tive than itself will decompose the salt of a more positive metal, 

 it may be expected, d fortiori, that it can decompose one of its 

 own salts. Instances of this are not wanting. 



Magnesium connected with platinum will decompose a mag- 

 nesium salt, the almost insoluble hydrate of magnesium being 

 found adhering to the negative metal. The deposition of zinc 

 en the plates of an old-fashioned battery, when the battery is 

 pretty well exhausted, is a well-known phenomenon. In our 

 experiments with copper and silver in conjunction in a solution 

 of nitrate of copper, we never succeeded in reducing the galvanic 

 action to nil by our utmost efforts to exclude all oxygen, and the 

 •whole of the present inquiry originated in an experiment 

 described by us before the Physical Society, that mercury and 

 gold in conjunction would decompose mercuric chloride, with 

 deposition not only of lower chloride, but also of metallic mer- 

 cury upon the gold. 



These experiments are inexplicable on the" theory that the 

 chemical action supplies the whole of the decomposing force, 

 but show that there is an antagonistic force produced somewhere 

 in the circuit which is greater in amount than the superior affinity 

 of potassium over magnesium for the negative radicals. 



Little doubt can be entertained but that this force is called 

 into existence by contact ; but our experiments do not teach us 

 whether the energy requisite to keep up the action results from 

 the disappearance of heat at the junction of the metals or 

 contact of the metals and liquids (an idea that has long been 

 in our minds), or at the expense of some other form of energy. 

 Of course a momentary disappearance of heat would give only 

 a momentary supply of voltaic energy ; but since the loss of 

 heat would be constantly made up by absorption from sur- 

 rounding objects, the action would be continuous. 



Linnean Society, Dec. 2.— Dr. G. J. Allman, F.R.S., 

 president, in the chair. — Mr. J. G. Baker made some remarks 

 on Pyrus liri-rgsii. The following papers were then read :— On 

 Polynesian P'erns of the Challenger Expedition, by Mr. J. G. 

 Baker. The new species amounted to ten or twelve, closely 

 allied to species already known, and establishing no new genus. 

 — (ienera and Species of Liliaceas, by Mr. J. G. Baker. The 

 present instalment, completing the series, comprises the Tribes 

 Anthericese and Eriosperinea; ; the latter characterised by re- 

 markably woolly seeds.— liotanical Notes from Darjeelmg to 

 Tongle, by Dr. C. B. Clarke. — On Edgaria, a nevr genus of 

 Cucurbitaceije, by Dr. C. B. Clarke. 



Chemical Society, Dec. 2.— Prof. Abel, F.R.S., president, 

 in the chair. — Dr. J. H. Gladstone read a paper, by himself and 

 Mr. A. Tribe, on the decomposition of alcohol and its homo- 

 logues by the joint action of aluminium and its halogen com- 

 pounds. The action on alcohol gives rise to hydrogen and 

 aluminic ethylate, a greenish white fusible solid, — The second 

 communication, a note on incense resin, by Dr. J. Stenh«use 

 and Mr. C. E. Groves, was read by the latter. The authors 

 have succeeded in obtaining a crystalline substance and a liquid 

 hydrocarbon from it. — Mr. J. Spiller gave a notice of the occur- 

 rence of native calcium chloride at Guy's Clifife, Warwickshire ; 

 after which Mr. G. S. Johnson described certain sources of 

 error in the ultimate analysis of organic substances containing 

 nitrogen, upon which an interesting discussion took place. — The 

 other papers were : On certain bismuth compounds, by Mr. M. 

 M. P. Muir ; and On bismuthiferous tesseral pyrites, by Dr. W. 

 Ramsay. 



Royal Microscopical Society, Dec. i. — Mr. H. C. Sorby, 

 F.R.S., president, in the chair. — A number of presents were 

 announced, including an injected specimen of the ova of 

 Ainphiuma presented by Mr. Beck. — A very useful addi- 

 tion to "microscopes with concentric rotating stage was ex- 

 hibited by Mr. Crouch, by which the instrument could be 

 accurately adjusted to the centre of the stage when different 

 objectives were employed. — Dr. Lawson exhibited and described 

 a new apparatus termed the Hematimetre, designed by M. Hagen 

 and constructed by Nachet, for the purpose of estimating the 

 number of corpuscles in a given quantity of blood. — Mr. A. W. 

 Bennett called attention to some minute organisms which he had 

 discovered upon the leaves of Drosera and other carnivorous 

 plants, and which he regarded as being intimately connected 

 with the process of nutrition. — A very interesting paper was 

 read by Prof. W. Rupert Jones, on Foraminifera with special 

 reference to their variability of form. The subject was pro- 

 fusely illustrated by large diagrams, models, &c. 



Manchester 



Literary and Philosophical Society, Nov. 2. — Mr. R. 

 Angus Smith, F.R.S., vice-president, in the chair. — M?. Peter 

 Spence, F.C. S., &c., exhibited a piece of 2 to 3-inch lead pipe 

 in which the metal had been entirely transformed into galena, 

 the crystallisation being visible through the whole of the speci- 

 men. The pipe had been used for the conveyance of gas ammo- 

 niacal water, and was sunk under ground. A considerable 

 leak of gas-water having occurred, a constant atmosphere of 

 sulphide of ammonium would surround the pipe, and this seems 

 to have been the cause of the conversion of the lead into sul- 

 phide, as only that part of the pipe which was in the vicinity of 

 the leak was found to be transformed. — On the principle of the 

 electro- magnet constructed by Mr. John Faulkner, by Prof. 

 Osborne Reynolds. The magnet which forms the subject of 

 this paper consists of a sofc iron bar with a flat plate attached 

 to one end, and surrounded by a coil of wire in the same way as 

 the ordinary electro-magnet. Outside this coil is placed a tube 

 of soft iron of the same length as that portion of the interior bar 

 which projects beyond the plate ; this tube has flat ends, one of 

 which is m contact with the plate, while the other comes up 

 flush with the end of the bar, so that a plate or keep placed over 

 the end is in contact with both the bar and the cylinder. The 

 magnet is excited in the ordinary way, by connecting the ends of 

 the wire which forms the coil with the poles of a battery. When 

 thus excited this magnet exhibits certain peculiarities as compared 

 with a common magnet The object of the paper was to suggest 

 explanations of these phenomena. 



Nov. 1 6. — Rev. William Gaskell, vice-president, in the chair. 

 — On an instrument for measuring the direct heat of the Sun, by 

 Prof. Balfour Stewart, F.R.S. The instrument generally em- 



