462 



NA TURE 



\_March 14, 



overlooked in the general theory of inheritance. I am fully 

 aware that I shall be accused of flat Lamarckism ; but a nickname 

 is not an argument. MARCUS M. Hartog. 



Cork, March 6. 



A Fine Meteor. 

 A FINE meteor was visible here to- night at 6.36 p.m. It fell 

 perpendicularly almost due north-north-east, disappearing about 

 20° ab )ve the horizon, and was then as nearly as pos-ible of the 

 brilliancy and colour of Venus, which was shining in the south- 

 west at the time. Length of path, I think, about 20°, but I am 

 not positive that I saw the beginning of it. 



B. WooDD Smith. 

 Hampstead Heath, N.W., March 11. 



Bishop's Ring. 



I AM informed by Miss E. Brown, of Cirencester, that she saw 

 Bishop's ring in full day-time as recently as last month, not far 

 from 12 o'clock one day, the sun being hidden behind a cloud at 

 the time. It appeared very similar in extent, as well as colour, 

 though not intensity, to what it did after the Krakatab eruption. 

 Also another day she noticed something like it when looking at 

 the sun simply through a dark glass. 



I have very occasionally myself in the last few years seen a 

 somewhat similar phenomenon, but duller and dirtier in colour 

 than Bishop's ring usually was, and which gave me the impres- 

 sion of being lower down in the atmosphere than that. I 

 attributed this to smoke or some other local impurity. It would 

 appear that the phenomenon seen by Miss Brown, out in the 

 country, cannot have been thus caused ; but I suppose that she 

 must really have seen the corona produced by volcanic dust, 

 through an exceptionally pure lower atmosphere. 



Sunderland, March. T. W. Backhouse. 



The Philosophical Transactions. 

 Most people who interest themselves in science would be glad 

 to possess a complete set of the Philosophical Transactions. But 

 in the first place complete sets are scarce, and in the second it 

 would be much too expensive f ^r ordinary people ; furthermore, 

 it is not in everyone's library that room could be found for its 

 reception. Now, Drs. Hutton, Shaw, and Pears m brought 

 out a first-rate abridgment of this valuable publication from its 

 commencement to the end of the year 1800. May I venture to 

 suggest that the Royal Society would be doing a good work by 

 publishing on the same lines a continuation up to the year 1900 ? 

 If they commenced now, and brought out a volume at intervals, 

 the whole thing might be completed in the early years of the 

 twentieth century. The cost ought not to be very great, and 

 probably nearly every free library would subscribe. S. 



ON THE COMPOSITION OF WA TER} 



r^URING the past year I have continued the work 

 ■^-^ described in a former communication on the 

 relative densities of hydrogen and oxygen (Roy. Soc. 

 Proc, February 1888, vol. xliii. p. 356 ; see also NATURE, 

 vol, xxxvii. p. 418), in the hope of being able to pre- 

 pare lighter hydrogen than was then found possible. 

 To this end, various modifications have been made in 

 the generating apparatus. Hydrogen has been prepared 

 from potash, in place of acid. In one set of experi- 

 ments the gas was liberated by aluminium. In this case 

 the generator consisted of a large closed tube sealed 

 to the remainder of the apparatus ; and the aluminium 

 was attached to an iron armature so arranged that, by 

 means of an external electro-magnet, it was possible to 

 lower it into the potash, or to remove it therefrom. The 

 liberated gas passed through tubes containing liquid 

 potash,- corrosive sublimate, finely powdered solid potash, 

 and, lastly, a long length of phosphoric anhydride. But 

 the result was disappointing, for the hydrogen proved to 



be no lighter than that formerly obtained from sjulphuric 

 acid. 



I have also tried to purify hydrogen yet further by 

 absorption in palladium. In his recent important memoir 

 {Amer. Chem.Journ., vol. x. N o. 4), " On the Combustion of 

 Weighed Quantities of Hydrogen and the Atomic Weight of 

 Oxygen," Mr. Keiser describes experiments from which it 

 appears that palladium will not occlude nitrogen— a very 

 probable impurity in even the most carefully prepared 

 gas. My palladium was placed in a tube sealed, as a 

 lateral attachment, to the middle of that containing the 

 phosphoric anhydride ; so that the hydrogen was sub- 

 mitted in a thorough manner to this reagent, both before 

 and after absorption by the palladium. Any impurity that 

 might be rejected by the palladium was washed out of 

 the tube by a current of hydrogen before the gas was 

 collected for weighing. But as the result of even this 

 treatment I have no improvement to report, the density 

 of the gas being almost exactly as before. 



Hitherto the observations have related merely to the 

 densities of hydrogen and oxygen, giving the ratio 15 '884, 

 as formerly explained. To infer the composition of water 

 by weight, this number had to be combined with that 

 found by Mr. Scott as representing the ratio of volumes. 

 The result was— 



2_X 15 884 

 1-9965 



I5'9H- 



Of course, this tube was superflii 

 veaient to retain it. 



the present case, but it was 1 



The experiments now to be described are an attempt 

 at an entirely independent determination of the relative 

 weights by actual combustion of weighed quantities of the 

 two gases. It will be remembered that in Dumas's in- 

 vestigation the composition of water is inferred from the 

 weights of the oxygen and of the water, the hydrogen 

 being unweighed. In order to avoid the very unfavour- 

 able conditions of this method, recent workers have made 

 it a point to weigh the hydrogen, whether in the gaseous 

 state, as in the experiments of Prof. Cooke and my own, 

 or occluded in palladium, as in Mr. Reiser's practice. So 

 long as the hydrogen is weighed, it is not very material 

 whether the second weighing relate to the water or to the 

 oxygen. The former is the case in the work of Cooke and 

 Reiser, the latter in the preliminary experiments now to 

 be reported. 



Nothing could be simpler in principle than the method 

 adopted. Globes of the same size as those employed for 

 the density determinations are filled to atmospheric 

 pressure with the two gases, and are then carefully 

 weighed. By means of Sprengel pumps the gases are 

 exhausted into a mixing chamber, sealed below with 

 mercury, and thence by means of a third Sprengel are 

 conducted into a eudiometer, also sealed below with 

 mercury, where they are fired by electric sparks in the 

 usual way. After sufficient quantities of the gases have 

 been withdrawn, the taps of the globes are turned, the 

 leading tubes and mixing chamber are cleared of all re- 

 maining gas, and, after a final explosion in the eudio- 

 meter, the nature and amount of the residual gas are 

 determined. The quantities taken from the globes can be 

 found from the weights before and after operations. From 

 the quantity of that gas which proved to be in excess, the 

 calculated weight of the residue is subtracted. This 

 gives the weight of the two gases which actually took part 

 in the combustion. 



In practice, the operation is more difficult than might 

 be supposed from the above description. The efficient 

 capacity of the eudiometer being necessarily somewhat 

 limited, the gases must be fed in throughout in very 

 nearly the equivalent proportions ; otherwise there 

 would soon be such an accumulation of residue that no 

 further progress could be made. For this reason 

 nothing could be done until the intermediate mixing 

 chamber was provided. In starting a combustion, this 

 vessel, originally full of mercury, was charged with 



