December 19, 1901] 



NA TURE 



161 



^ = ■2.2 8 



M = 86o" 

 loga = 0'4i03 

 Period =4" 1 3 years. 



OUR ASTRONOMICAL COLUMN. 

 An Asteroid-Orbit of Great Eccentricity.— Prof. E. C. 

 Pickering announces that from an examination of a plate taken 

 on August 14, 1901, with the Bruce telescope. Dr. .Stewart 

 found an asteroid having the "great southern declination, - 62°. 

 Fourteen photographs were taken up to November 13, furnishing 

 approximate positions for the computation of the orbit. A 

 circular orbit was first calculated, which gave the .surprising 

 result that the heliocentric diurnal motion e.xceeded 2200", indi- 

 cating a distance from the sun less than that of any known 

 asteroid. Prof. Newcomb furnishes the following elements :— 



Epoch 1901, October 2-627 G.M.T. 



M = i58 30 

 <» = 30i 19] 



8= 35 48 -1900- o 

 i= 18 38J 



The uncertainty of the elements u> and a may be about ± i'. 



It would thus appear that the ellipticity of this new planet 

 is in con,siderable excess over that of any previously known 

 asteroid. The only others for which <f exceeds 20° are : — 



Eva (164) 20 19 



Istria(i83) 20 27 



The new asteroid was near perihelion at the time of its dis- 

 covery, moving rapidly round the sun at a distance of about i'6. 

 It is rapidly moving north, and will soon be available for ob- 

 servation from northern observatories, as shown by the following 

 approximate ephemeris for Greenwich midnight : — 



1901. R.A. Decl. 



h. m. . , 



Dec. 2I'S 



Jan. I0'5 



,. 30'S 



Bright Meteor of December 16. — An exceedingly 

 brilliant meteor was obseived at South Kensington on the 

 evening of Monday, December 16, about 6'45 p.m. Starting 

 from near o Persei, about 60' elevation, it travelled in a 

 northerly direction inclining downwards until, after a path of 

 about 30°, it disappeared beneath the Pole star. The meteor 

 was two or three times brighter than Capella, and appeared of 

 a similar tawny yellow colour, although this might have been 

 mainly due to the slight fog prevailing at the time. The 

 trajectory was practically rectilinear and the movement very slow. 



THE INERT CONSTITUENTS OF THE 

 A TMOSPHERE} 

 'X'HE discovery of an element always awakens interest ; for 

 the total number of the known elements does not exceed 

 seventy-five, and all the various forms of matter which exist on 

 this globe are necessarily composed of these elements. 



Elements must not be regarded as isolated entities, each 

 self dependent, having no relations with its compeers ; on 

 the contrary, all the elements exhibit certain connections with 

 their neighbours ; and there is to be traced an orderly progression 

 from one class of elements, strongly electro-positive in charac- 

 ter, metallic in appearance, very inflammable when heated in the 

 air, and at once attacked by water, to another class, highly 

 electro-negative, transparent, unattackable by oxygen, and with- 

 out perceptible action on water, through a number of connecting 

 links, each of which serves to soften the transition. 



These elements have been arranged in series, and it is by 

 considering the method of arrangement that our interest is 

 awakened. 



The revival of the hypothesis of the atomic constitution of 

 matter by IXilton and of his attempt to determine the atomic 

 weights of the elements was not long in provoking the guess 

 that perhaps there could be found 'some connection between 

 the numbers representing the relative atomic weights of kindred 

 elements. But, as is well known, the state of knowledge in 

 Dalton's day was not sufficiently advanced to enable him to 

 attribute to elements their correct relative atomic weights ; and 

 it was not until the eminent professor of chemistry in Rome, 



1 .^bstr.-ict of an evening lecture delivered at the meeting of the British 

 Association at Glasgow, September 13, by Prof. W. Ramsiy, F.R.-S. 



NO. 1677, VOL. 65] 



Gannizzaro, whose jubilee has recently been celebrated, pointed 

 out the bearing on Dalton's numbers of all the facts accumu- 

 lated up to the year 1S56 that the close relationship between the 

 atomic weights and the properties of the elements was sug- 

 gested by John Newlands. Some years later Lothar Meyer and 

 Dmitri Mendeleef amplified and elaborated the ideas which had 

 first been propounded by Newlands ; and the periodicity of the 

 atomic weights and the gradual variation of the properties of 

 the elements and their compounds were established on a firm 

 basis. 



The division of the elements into metals and non-metals cor- 

 responds broadly with another well-marked division — that into 

 basic and acidic. Generally speaking, it is the oxides of the 

 metallic elements which react with water to form bases, and 

 those of the non-metals which form acids with water. Accord- 

 ing to modern ideas, bases, by the mere act of solution in water, 

 are supposed to be split up into portions, for which the 

 term ion, invented by Faraday, has been retained ; one ion is 

 charged by the process of solution with a positive charge, and 

 that portion is usually a metal ; the other portion, which con- 

 sists of one or more groups of hydrogen and oxygen in combina- 

 tion, termed " hydroxyl "— OH — has a negative charge. A 

 base, indeed, is a compound which splits in this manner. On 

 the other hand, an acid, when dissolved in water, undergoes an 

 analogous split ; but in this case the electro-positive ion is 

 always hydrogen, while the electro-negative ion inay either be 

 an element such as chlorine, or a group of elements such as 

 exist in nitric acid (NO3). 



The order of the various elements in the electric series has 

 been determined; and not inerely determined, but to each has been 

 attached a numerical value. This value is identical with what is 

 termed "chemical affinity"; and it represents the electric 

 potential of the element with reference to an arbitrary starting- 

 point, which does not differ much from that of nickel, an 

 element closely related to iron. Only a few such values have as 

 yet been determined numerically ; instances may be chosen from 

 the magnesiuin group, where the numbers run : Magnesium 

 = + l'2 ; Zinc = + o'5 ; Cadmium = + o'lg ; or from the 

 fluorine column, where the numbers are : Fluorine = - 2-0 ; 

 Chloiine = - 16; Iodine = - o"4. In each case the potential, 

 positive or negative, is the highest for the element with smallest 

 atomic weight, and decreases with increase of atomic weight, 

 for elements in the same column. The order of some of the 

 elements is : Cs Rb K Na Li Ba Sr Ca Mg Al Mn Zn Cd Fe" 

 Co Ni Pb H Cu Ag Hg'Pt'" ' Au' " ; and for electro-negative 

 ions, S" O" I Br CI F ; the first element, caesium, being the most 

 electro-positive, and the last, fluorine, the most electro-negative. 



The order given above corresponds fairly well with the order 

 in the periodic table, passing from left to right. But, as in the 

 table, the atomic weights follow each other continuously round 

 the cylinder or round the spiral, the abrupt change frona ele- 

 ments of an extreme electro-negative character, like fluorine to 

 sodium, an element of highly electro-positive character, or from 

 chlorine to potassium, has always appeared remarkable. The 

 old dictum, Natura nihil fit per sallum, if not always true (else 

 we should have no elements at all, but a gradual and continuous 

 transition from one kind of matter to another — a condition of 

 affairs hardly possible to realise), has generally some spice of 

 truth in it ; and it might have been predicted (and the forecast 

 seems to have been made obscurely by several speculators) that 

 a series of elements should exist which should exhibit no electric 

 polarity whatever. Such elements, too, should form no com- 

 pounds, and, of course, should display no valency ; they should 

 be indifferent, inactive bodies, with no cheinical properties. 



The discovery of argon in 1S94, followed by that of terrestrial 

 heliuin in 1895, and of neon, krypton and xenon in 1898, has 

 shown the justice of the foregoing remarks. Inasmuch as the 

 methods employed for the isolation of these elements illustrate 

 their properties and confirm the views as to their inertness and 

 lack of electric polarity, I propose to sketch shortly the history 

 of their discovery. 



An accurate investigation of the density of atmospheric 

 nitrogen and of nitrogen prepared from its compounds led Lord 

 Rayleigh to inquire into the cause of the density of the 

 nitrogen of the atmosphere exceeding that of " chemical 

 nitrogen " by about one part in two hundred, whereas the 

 accuracy of his experiments was such that it would have 

 excluded an error of one part in five thousand. I need not 

 here allude to the reasons which were at first put forward to 

 account for this anomaly ; suffice it to say that they offered no 



