n8 



NA TURE 



[Dec. 5, 1889 



of platinum. Daring the process of his memorable work upon 

 the isolation of fluorine by the electrolysis of hydrofluoric acid 

 containing hydrogen potassium fluoride, one of the most remark- 

 able phenomena noticed was the rapidity with which the 

 platinum rod forming the positive electrode was corroded by the 

 action of the liberated gaseous fluorine. It was surmised that a 

 fluoride of platinum was the product of this action, but hitherto 

 all efforts to isolate such a body have proved unsuccessful. In 

 fact, for a reason which will be discussed subsequently, it is im- 

 possible to prepare platinum fluoride in the wet way. M. 

 Moissan has, however, been enabled to prepare anhydrous 

 platinum fluoride by the action of pure dry fluorine itself upon 

 the metal. It was found at the outset that, when fluorine is free 

 from admixed vapour of hydrofluoric acid, it exerts no action 

 whatever upon platinum, even when the latter is in a finely- 

 divided state, and heated to 100° C. But when the temperature 

 of the metal is raised to between 500° and 600° C, combination 

 readily occurs with formation of tetrafluoride of platinum and a 

 small quantity of protofluoride. The moment the gas is mixed 

 with a little vapour of hydrofluoric acid, the action is immensely 

 accelerated, and then occurs readily at ordinary temperatures. 

 The same rapid action occurs when platinum is placed in hydro- 

 fluoric acid saturated with free fluorine, which accounts for the 

 disappearance of the positive terminal during the electrolysis. 

 In order to prepare the fluoride of platinum, a bundle of wires 

 of the metal is introduced into a thick platinum or fluor-spar tube, 

 through which a current of fluorine gas from the electrolysis 

 apparatus is passed. On heating the tube to low redness, 

 the wires become rapidly converted to fluoride, when they 

 are., quickly transferred to a dry stoppered bottle. If the 

 operation is performed in a platinum tube, a large quantity 

 of fused fluoride remains in the tube. The tetrafluoride of 

 platinum, PtF4, formed upon the wires, consists either of fused 

 masses of a deep red colour, or of small buff"-coloured crystals 

 resembling anhydrous platinum chloride. It is exceedingly 

 hygroscopic. With water it behaves in a most curious manner. 

 With a small quantity of water it produces a fawn-coloured 

 solution, which almost immediately becomes warm, and decom- 

 poses with precipitation of hydrated platinic oxide and free 

 hydrofluoric acid. If the quantity of water is greater and the 

 temperature low, the fawn-coloured solution may be preserved 

 for a few minutes, at the expiration of which, or immediately on 

 boiling the solution, the fluoride decomposes in the manner 

 above indicated. This peculiar behaviour with water explains the 

 impossibility of preparing the fluoride in the wet way. When 

 the anhydrous fluoride is heated to bright redness in a platinum 

 tube closed at one end, fluorine at once begins to be evolved as 

 gas, and if a crystal of silicon be held at the mouth of the tube it 

 takes fire and burns brilliantly in the gas. The residual platinum 

 is found on examining the contents of the tube to consist of dis- 

 tinct crystals of the metal. Hence by far the most convenient 

 method of preparing fluorine for lecture purposes is to form a con- 

 siderable quantity of the fluoride first by passing the product of the 

 electrolysis over bundles of platinum wire heated to low redness, 

 and afterwards to heat the fluoride thus obtained to full redness 

 in a platinum tube closed at one end. It only remains now to 

 ■discover another method of preparing fluoride of platinum in the 

 dry way, to be able to dispense with the expensive electrolysis 

 apparatus altogether. M. Moissan has also prepared a fluoride 

 of gold in the same manner. It is likewise very hygroscopic, 

 •decomposable by water, and yields gaseous fluorine on heating 

 to redness. 



SOCIETIES AND ACADEMIES. 



■ London.] 



Royal Society, November 21.—" On the Local Paralysis of 

 Peripheral Ganglia, and on the Connection of Different Classes 

 •of Nerve-Fibres with them." By J. N. Langley, F. R.S., 

 Fellow of Trinity College, and W. Lee Dickinson, Caius 

 ■College, Cambridge. 



We found that in the rabbit, 30 to 40 milligrams of nicotin 

 injected into a vein stopped the effect of stimulating the sym- 

 pathetic in the neck, not only on the pupil, but also on the 

 vessels of the ear. It occurred to us that this action of nicotin 

 might be due to a paralysis of the nerve-cells of the superior 

 •cervical ganglion, and not to a paralysis of the peripheral 

 endings of the sympathetic nerve. On testing this view, we 

 ifound that, after a certain dose of liicotin, stimulation of the 



sympathetic fibres below the ganglion does not produce dilation 

 of the pupil or constriction of the vessels of the ear, whilst 

 stimulation of the sympathetic nerve-fibres above the ganglion 

 produces these changes in the normal manner. 



The method of action of nicotin can be tested in a more direct 

 manner by local application to the isolated nerve and ganglion. 

 When the sympathetic in the neck has been brushed over with 

 a I per cent, solution of nicotin, stimulation of it produces the 

 usual dilation of -the pupil and constriction of the vessels of the 

 ear ; but when the superior cervical ganglion and the filaments 

 proceeding from it have been brushed over with the i per cent, 

 nicotin, stimulation of the sympathetic in the neck is found to be 

 completely without effect, while stimulation of the filaments 

 running from the ganglion to the carotid arteries produces the 

 normal action. 



Hence nicotiit paralyzes the cells of the superior cervical 

 ganglion. 



On the fibres of the cervical sympathetic, which are vaso- 

 motor for the head generally and secretory for the salivary 

 glands, we have made a few experiments only ; but so far we 

 have been unable to detect any effect from stimulating the 

 sympathetic in the neck after nicotin has been applied to the 

 ganglion. 



We conclude that the dilator fibres for the pupil, the vaso- 

 constrictor fibres for the ear {probably also those for the head 

 generally), and the secretory fibres for the glands, end in the cells 

 of the superior cervical ganglion. 



Ganglion of the Solar Plexus.— In. the dog, cat, and rabbit, 

 the splanchnic nerve on the left side runs to two chief ganglionic 

 masses, which we may call respectively the coeliac and superior 

 mesenteric ganglia. The renal ganglia are scattered, but in the 

 dog the chief one often lies underneath the suprarenal body, 

 and in the cat the chief one is placed between the artery and 

 vein about \ inch from the superior mesenteric ganglion. 



To determine whether the inhibitory fibres of the splanchnic 

 end in the nerve-cells of the solar plexus we proceeded as in the 

 case of the superior cervical ganglion. Having ascertained that 

 the application of i per cent nicotin to the splanchnic leaves its 

 inhibitory power unaffected, we found that nicotin applied to 

 the whole plexus at once abolishes the inhibitory power of the 

 splanchnic ; but inhibition can still be produced by stimulating 

 the fibres proceeding from the ganglia. Hence, the inhibitory 

 fibres of the splanchnic end in the cells of the solar plexus. 



Our experiments are not sufficiently numerous, especially 

 with regard to the connection of the coeliac ganglion with the 

 stomach, to make it certain that the one ganglion is entirely 

 connected with fibres to the intestine, and the other with the 

 fibres to the stomach ; but we think they show that in the main, 

 and possibly altogether, the stomachic inhibitory fibres of the 

 splanchnic nerve end in the cells of the cceliac ganglion, and the 

 intestinal inhibitory fibres of the splanchnic end in the cells of 

 the superior mesenteric ganglion. 



We find, however, that the motor fibres of the vagus for the 

 stojiiach and intestines do not end in the no'je- cells of the solar 

 plexus. 



The connection of the vaso-motor fibres of the splanchnic 

 with the nerve-cells of the solar plexus can be determined by 

 taking a tracing of the arterial blood-pressure and stimulating 

 the splanchnic before and after the application of nicotin to the 

 ganglia. By applying nicotin to both ganglia, the rise of blood- 

 pressure caused by stimulating the splanchnic is reduced to very 

 small limits, and by applying it to the renal plexus as well, the 

 effect of splanchnic stimulation on the blood-pressure is abolished. 

 Since in this case there is no fall of blood-pressure, we conclude 

 that the vaso-dilator as 7vcll as the vaso-constrictor fibres of the 

 splanch?tic end in the cells of the solar and renal plexuses. 



Combining oncometer observations on the dog with blood- 

 pressure observations on the rabbit and cat, we think there is 

 fair evidence that the splanchnic vaso-motor fibres for the kidney 

 end in the cells of the renal plexus. 



We have experimented upon various peripheral ganglia other 

 than those mentioned above, and, though our results are as yet 

 incomplete, with essentially similar results ; that is, we have 

 obtained an abolition of the effect of some one or more of the 

 classes of nerve- fibres running to them. We think, then, there 

 is fair ground to conclude that by stimulating the nerve-fibres 

 running to and those from any peripheral ganglion, before and 

 after the application of dilute nicotin to it, the class of nerve-fibres 

 which end in the nerve-cells of the ganglion can be distinguished 

 from those luhich run through the ganglion zvithout being con- 

 nected with ne)-ve- cells. 



