February i6, 1899] 



NA TURE 



579 



Muring the period the comet moves in a north-easterly direc- 

 tion, its path lying about midway between the belt of Orion and 

 Sirius. From March S to lo it will be passing near the fourth 

 mag. double star 3 ( H) Monocerotis. 



CoMKT CiiASK, 1S98 VIII. — E. F. Coddington gives, also 

 in Ast. Noih., No. 3544, a revised ephemeris and table of 

 elements for this comet, which he has computed from observ- 

 ations made by him at Mount Hamilton on November 23, 

 December 7 and December 16, 1S9S. 

 EUmeiils. 

 T = 1898, Sept. 20-15344 G.M.T. 



« = 4 37 59-9 ) 

 « = 95 S> 3S'9> «899'o 

 « = 22 30 20'3 ) 

 log ./ = 0-358892. 



Ephemeris for Crceiiwieh .Mi(liiii;/it. 



111. 



Feb. 16 



h. 



II 3 0-99 



II o 58-16 



24 ... 10 58 49 87 



28 ... 56 39-81 



Mar. 4 ... 54 31-44 



8 ... 52 28-31 



12 ... so 33-54 



16 ... 48 50-19 



20 ... 47 20-60 



24 ... 46 6-59 



28 ... 45 9-42 



April 3 ... 10 44 16-87 



4-36 47 38-3 ... 091 



37 IS 10-3 ... -87 

 38 167 ... -83 

 56 47S ... -79 



38 lo 40-0 ... -75 



19 509 •• 71 

 24 26-6 ... -67 

 24 32-9 ... -63 



20 25-6 ... -59 

 12 20-8 ... -55 



38 o 36-7 ... -51 

 + 37 36 49j - 0'48 



Comparison of the elements leads to the orbit being considered 

 almost parabolic, and hence there is no probability of its being 

 identical with that of Comet 1S67 I., as has been suggested. 

 The comet is now rapidly receding from the sun and decreasing 

 in brightness. It is moving slowly westwards between the pairs 

 of stars 7, land X/iUrsie Majoris. 



Vari.M'ion ok Si'Et-i-RUM ov Orion NiCHi'i.A.— Much has 

 been recently said as to whether the spectrum of this nebula is 

 ditlereni in ditl'erent regions. There seems to be no doubt that 

 in different parts certain lines are intensified or reduced relatively 

 to others, but observers are not yet agreed as to the reality of 

 the dirt'erence, many a.scribing it to physiological causes. I'rof 

 J. K. Koeler, with the Lick 36inch refractor, has examined it 

 with reference to this matter {Ast. Nach., No. 3541). Near the 

 star Hond 734 the strongest line was H/3 (F). With the slit on the 

 lluyghenion region, near the trapezium, the strongest line was 

 the chief nebula line (\ 5007), while Up and the second nebula 

 line {\ 4059) were about eipially bright, but much less intense 

 than the chief line. Still keeping the slit in this region, the 

 vertical aperture of the spectroscope was diminished without 

 altering the resolving power. When the brightness was 

 sultiiiently reduced, H/s ami the line K 4959 disappeared, 

 leaving \ 5007 alone visible. Thus in one part of the nebula 

 ll|3 alone was visible, in another A 5007. This is inexplicable 

 on physiological grounds, and would seem to point to real 

 dilVerences in the composition of the nebula. 



I.Airi'uuE Determination.— In the determination of lati- 

 tude by Tallcott's method, the apparent mean declination of a 

 pair of stars has to be deduced from observations of the star 

 corrected by constant factors dependent on the position of the 

 stars. To facilitate these reductions II. Kimura, of the Tokyo 

 Observatory, gives formul.e and tables for constructing mean 

 star factors (.-/i/. Nacli., Hd. 148, No. 3541). There are also four 

 special tables of these constants given for the particular latitude 

 0-39' 8' lo", which is that chosen for a number of stations 

 for the coming international work of determining latitude 

 variation. 



Lynn's "Remarkaih.I': Comets." — A new edition— the 

 seventh — of this handy little volume has been published by 

 Mr. I-;dward Stanford. The periodic comets which may be 

 expected to return this year are stated by Mr. Lynn as follows : 

 Spring — The comet of 1S60, connected with November meteors 

 (period, 33^ years). Summer — Tultle's comet (period, 13^! 

 years), Tempel's second periodical comet (period, SJ years), 

 and Holme's comet (period, nearly 7 years). Winter — 

 Finlay's comet (period, (i.|. years). 



NO. 1529, VOL. S9] 



THE THEORY OF THE STASSFURT SALT 

 DEPOSITS. 



" ""PlIE formation of the salt deposits at Sla.ssfurt, Wieliczka, 



and other places, .so far as they are of an oceanic origin, can- 

 not receive a detailed explanation until the conditions of equili- 

 brium afl'ecting the salts dissolved in sea-water have been 

 subjected to a systematic investigation. 



" First of all, it must be ascertained what grouping the radicals 

 assume in the solid state ; that is to say, what solid substances 

 .separate out as sea-water is evaporated. Further experiments 

 will then show us how the composition of sea-water is afTected 

 by the presence of the various solids, and whether, and to what 

 degree, changes take place — loss of water of crystallisation, 

 formation of double salts, and kindred phenomena — as the com- 

 position of the .solution alters, until linally the water is wholly 

 evaporated, and a stable system of solids is left behind." 



The comprehensive programme of work thus indicated by 

 Dr. Meyerhofl'er in 1895 has been seriously entered upon, and 

 the tirst instalment of results appears in a recent number of 

 the Zeitschrifl fiir Physikalisehe Cliemie, vol. xxvii. p. 75.' 



The investigation promi.ses to be of great interest and im- 

 jjortance, viewed both from the theoretical and practical stand- 

 points. The problem of determining the conditions under which- 

 a series of salts have been deposited during the concentration of 

 a dilute solution, is very much more complicated than might at 

 lirst sight appear, and can only be solved by the application of 

 methods and principles that are of recent discovery. The re- 

 searches that render the investigation possible have been mainly 

 conducted during the past few years in the laboratory of I'rof. 

 van 't Hoff; and those who are acquainted with the admirable 

 " Etudes sur les equilibres chimiques " (translated into English 

 by Dr. Ewan), and with the later publications of van 't Hoff, 

 will know how ably he has developed the theory of equilibrium 

 as applied to the existence of hyilrates and of double salts. 



The plan of work, with respect to the Slassfurt deposits, is as 

 follows. The chief dissolved substances in sea-water consist of 

 salts formed from CI, SO4, Na, K and Mg ; the first problem is, 

 therefore, the complete investigation of the salts and solutions 

 producible from these radicals. Even within these limits the 

 investigation is too complicated ; .so that, first of all, systems 

 formed by water with the chlorides and sulphates of K and Mg 

 are dealt with. Then the consideration is extended to such 

 systems with the addition of rock salt, and the first part of the 

 investigation is concluded. 



In the second part the less soluble and less abundant com- 

 ponents of the deposits will be considered. Calcium, in the 

 first instance, will receive attention ; and then the compounds 

 of boron, bromine, and iron. 

 The groups of substances to be dealt with are as follows : — 

 (i) (."iroup formed from the sulphates and chlorides of K and 

 Mg. 



MgCI.. and its hydrates. 



Sylvin'e, KCl and K„SOj. 



MgSO^ and its hydrates : Carnallite, MgCl.., KC1.6H.p. 



Schiinite, Mg.SO,, K ,S0,.6I1.,0, and potassium astra- 

 kiinite MgSO,, K,SOj.4H.,6. 



Kainite, Mg.SOj, Kt'1.3H..O, and Langbeinite 2MgSOj 

 K.jSOj. 



(2) With the addition of NaCl. 



NaCl and Na„SO, and their hydrates. 

 Astrakanite (IJlodite), MgSOj, Na.jSt)^, 4II.X). 

 Glaserite (Penny's .salt), K^Na (SOJ.j. 



(3) With the addition of Calcium. 



CaClj and its hydrates. 



Tachydrite, CaCI.,.2MgCl...l2ll.,0. 



Gypsum, CaS04."2ll,_.0, Anyhdrite GaSOj, and their 



double salts, such as Krugite, Glauberite, Polyhalitc, 



.Syngenite, Mamannite, \c. 



(4) With the addition of Boron, Bromine and Iron. 



Boracite, Stassfurtite. 

 Magnesium bromide. 

 Potassium ferrochloride, iS:c. 

 The first instalment of the research, now published, deals 

 exclusively with the hydrates of magnesium chloride. The 



I iHier .\nwenduiiKcn derGlclchgewichlslehre .-luf die Bildung occnnivhor 

 Sal/alilaKCruilECM, mil besondcrei lit-riicksicluigung des Stassfurlcr Sal/- 

 lagers. Von J. H. van l llofl'uiKl W. Mcycrholler. 



