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Page Prof. Faraday on the Magnetic Relations and Characters of the

Metals 1

Dr. J. Stenhouse on the Products of the Distillation of Ben-

zoate of Copper ,. 3

Mr. G. G. Stokes on the Aberration of Light 9

Mr. W. De la Rue on the Structure of Electro- precipitated

Metals (with a Plate) 15

Dr. A. W. Hofmann on the true Composition of Chlorindatmit ilO Mr. T. Richardson's Analyses of Farm- Yard Manure, and of

Coal-Gas 23

Mr. R. Hunt's Contributions to Actino-Chemistry 25

Experiments on the Electric Discharge of- the Jar. (Extract of

a letter from M. Matteucci to M. Arago.) 35

Mifl"A?i ©si,ytey"6»'iS[lg^te*aical;iGouplei86Jii'Pjpq, )?^% jfisiplifiiihU "38

jects were seen invertedoViil.,?. .•ji).cvg.4sW-5-i".m3noUnav/!ii3iu:j>u^9'f41 Mr. E, J. Lowe on a Magnificent Meteor seen in Nottingham- shire 41

The Rev. B. Bronwin's Reduction of the Four Forms of cu in Jacobi's General Transformation of an Elliptic Function to

one form only : 4*2

Mr. R. Moon on Fresnel's Theory of Diflfraction 46

Proceedings of the Royal Society 52

Cambridge Philosophical Society 56

Royal Astronomical Society 60

Meteorological .Observations for May 1845 79

Meteorological Observations made by Mr. Thompson at the Garden of the Horticultural Society at Chiswick, near London ; by Mr. Veall at Boston ; by the Rev. W. Dunbar at Applegarth Manse, Dumfries-shire ; and by the Rev. C. Clouston at Sandwick Manse, Orkney 80


Prof. W. A. Miller's Experiments and Observations on some Cases of Lines in the Prismatic Spectrum produced by the passage of Light through Coloured Vapours and Gases, and from certain Coloured Flames. (With two coloured Plates.) 81

a 2


CiftW'ii^'Wi* 'vol.' '*«ifiiJ^w^mim/s«;tirE«

.If. J:-R. Young on Imagft{Sf^'^^8S?oteaPtfc^i* *!i«BPfb»fooi4

^(.pohjugate Points . Ml^r H

*Dfs. J. Blytli ahd A. W, Hofmann oa g#fta^. and sume of

p^hc Products of its (lccomposi1fk^f^y^MM<?:l¥.9^.3*P.^.^«?9';i|^^ jBjf. T. Graham's Note on the usefid -applications of -the Hfe^SIMf^'^ Sime 6f Gas-tvovks •.:•.:: ; . ; : ; •"f'f".^*.":^ .^.^M/y?^. ?rfi P§4 m R: D. Thomson's Examination clTBaHiflgtkJf^nfimi/jraap f^fe Mr. "J. 'Cockle on the Jlesolution of Equations of ctSfoplfttesdO

gp^egrck ■. .^VW^'VVVV/:'; )': .^^»?5Bf^

j!Ee KeV. S. Eafnshaw on- a certain Method of rei^res^entllagiljyfq ^

pp^iagrariaS the Results of Observations . ". . Fi n^^)

jPf. J. StenhoUse on the Action of ChloTine on Cinxianaic ati^^al/. •benzoic Acids . r. . . ...... . \'.\ . . .-. •. % -. -H^A \ .rr-T-.-r^-rr-i^

Proceedings of the Royal Society 137

Royal Astronomical Society 144

Researches on Shooting Stars, by M. Coulvier-Gravier 153

On the supposed occurrence of Phos])horic Acid in Rocks of

Igneous Origiij, ]jy Prof. C. Kersten 155

Examination of '^dM Nat^e-^an4 ^kitifiiiS ^xiikip6iihds of Phos- phoric Acid, by C. Rammelsberg 156

On the fetif-lictur^Mand <Relati««teJ€fe OdrhaHtesiona ot&eiffiiiiteayl/. ' ^^rian Fossils, bjt-MK tfi'-WJ^«Dterii9iail..Jci. Jk biwu'i gasiT-IislSS Eruption of Ve*tt*i^t«rii .no. X9li'(X\-iX ,T. hue. as-gslaeU ..a .aaeaal^S 'Ji^teorological Observations for. June 1845 aaiiKsdaillSQ

edi id boouboiq ifiioiiioaia ^o siaanuO no n^villua .W .iM

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Mr.-t«^?Mlivarfi5ii'ffi%rfi^^ytt?eA(^Pf»§«f«fe^ ,,^^,ana^MihaSS^.{'?.^X.«!\ ?'Ap.^. ?i^Lv}. PPP^hoi . . ; ;U61• ' 'Fr C. 'Henrici's Observations on i1SS"PB€^^id Application;«fM

Electricity j\l^lW?^l-)9APPr XA-ri-il64

Dr. H. Kolbe's Contributioils^^^^ffie K[fi§wfedge of ConjtigAtdt

Compounds ..•.•.•.■.;.•.•.•.•.•...■■••• .......... 171

Drs. J. S. Muspratt a.xid."J^:-'W[^WSfmSS^on Toluidine, a riew ' '■

^, ^Organic Base .... :'l'}y. .^PlX fl^pfnij^i ^ . 178

"Sir p. Brewster's Obser\'^tions connected with the Discovery

^ of the Composition of Water 195

■'Prof. Scho2nbein's Observations on Ozone as compared to

j„„Chlorine 197

,^Mr. J. P. Joule on the. Existence of an Equivalent Relation be- _ , tween Heat and tbe ordinaiy Forms of Mechanical Power. .• 2©5 ^Mr. S. Holker's Examination of Dr. Dalton's New Method bfnO M'ea'suring the Water of CryStallizatiott contained diff«tt"ifj'':^ '^ -^^'ent varieties of Salts l^V^'PV?^ . KK'ii .- ^VPk^fi^'il .lo. ^Mpei"^ 207

le Royal^ Astronomicaf ^ciety enM^srs^uldodZ

^(litbnal.Nqte.tp Mr. Sullivan^^jpftp^p^j^j/glj ^J iM^i^lrflgg

fyq the New Metal Ruthenium. . . . . . ..... &i.tayf:a:B^ «l<5 VniiS

ObsQ0»tio9ap9dtl^^i|Wg,^lemoirs, by %!! ^^^iddO: .X" .W ^^laminatipn pf some Native and Artificial 9"'^P°"J^ . ."^aoTlaCL

^^e great Symmetric^ Baigfflg^mvt^ eJloa^Hdift-^diMsmOgxI MetfftBplae8ii^^g5v^J^ft|f9r^^oM7?dilJ-ftO-^8Wrfh&ja '.L iffi

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-eorfq to 8btiiU^M^M^&ttT4?Swt^m\o noiJBnlniBza

361 ........ i2i3J«I'jranij3H ,0 y<^ ,bioA ohorfq

MesstfiiaSiaWQ BinneyiiindiR; HarknessfsiAq$»#i^)»l'o^)*§^§Sl nO eeisil. Trees found at .St. .Helen's (with /|f'\Y^ MfeJ^fsT .sHaao^ ii«h241 eiifessEs. D.. Maclagau.aod T, G. Tillcy on timJ&i^m^^9fh'iS{u-i:^ 6fi[Bebeerine .., ... . . ....Li-Bl. »'.4. ».;..* <<4'i'vli^-.'-»vvrO •f'lareolo'ioaj;^^

QMr, .W..,G- Armstiong on the Siiherpidal Conditioii QJAjiqmds .267 Mr. VV. Sullivan on Currents of Electricity produced by the

Vibration of Wires and Metallic Rods 261

Lieut.- Col. P. I. Yorke on Brown Iran Ore 264

Mr. R. Warington's Observations on the Action of Animal

Charcoal 269

Mr. H. Henn^RB!Ht]?q^fKili.g9l9»9^af3P^f^<^^J>^;r to Regis- tering the Thermometer and Barometer 273

Mr.^ H.. Hunt 'is; Qonfeibvifio^ tp Aqti^Prfih^a^ftyiiTTTStef ^- .il/: Idimical Changes produced by the Solar Rays on s^^'J|lfi^tp-^,

graphic Preparations exam^n^^^ i^n-^iKvitnv-is?^*;)- ft'fcii,^'^ 'W* ■^) ^\^ t^Mr. S.. M. Drach's Proof of Fermat's Undemonstrated Theorem,, ^ *

f tin =1 pra .... ..^ . . ^. . ; ^^^^^^,. . y.- V. ^;-. \;- •rfrfli:i'QWnioo286

Dr.J^<^t^|lft«MtJ«»ja%^^^IHffl!BHa|#eW<^fl^^ «T : phate of .tiiine, and Magnesia from Unne /pf. ^Q^Jj^jJ^W)

P^jtvposes/: . . ; . ..fm-bolfisamo •erraiJirni^Ji'^^ ''\'i-'-r H- :(1 -^^^ cMr.,J. Cockle's Supplementatj Repjkgj^ ^ ELmpation^^^^y

oa;the Theory of E§H^ti(gn%io. enoh^yTjadO -fmadapA^.i •.^o?^^ vMr. W. Cruiu on the Action of Bleaching Powder on tt]^J:jgJ^

of;, Copper and Lead ..:)„sWg: ^di tmsixjnh'.^-.i: .Mj^

^/Proceedings of the Royal Astroaon49^§9fii^te ^^.^^h TOSWJ^J? On Oxidatiou by means of Cyanogen, by M. Boudault . .r, .^ ^^7 Supordsidizement.^f AletalUc Uxidp ,by w^fin^. of,fh|i,f'^^gg^)j xOL'cyauide of Potassium, by M. Boudault v.^i^Q-'^o ^oiieh^^ ^m^^^

Phosphbrifc Aoid fotttfd-aJi^} sdlktdgt8al(l'jRtoT<jU»PnlI/.to. gtiin'si^J A'< ' »H) Exiamiuation of some Nativ6iki(d§A»l*fidy t&ffi'pe'oiifl^jb^^bi^-^o t '^horic Acid, by Cb'il-cimtkieyb^lQ'i.^iiViii^i-WSiJO.k^JaojPTo^iai^

Arialysis of Taurine ... ..■,..,,.-.• .w .• . .^S^i^T. -.-rr-r~ . . . "Si 8

Double Salt of [Bi] chloride of Mercury and Acetate of Copper 318

Rain during the Present Year 319

Meteorological Observations for August 1845 319

Table 320

>i:un/,:i vMci -nx/zj) h-ahiawa

eot NUMBER- CLXXXL— NOVEMBER. .^^-^ I viol.

-i73iq Ion fiJ'jafoO luTJvafe 'to aJnomalS tiill no briiH .H .1. .'iM

kk^. J. OhaiKs'sJ^tieoreticai -Explanation of thtvk!^(M*^glPdii'^<iF*^ , , T ;„T,> 7BbG-u;T.Toi4 /d-iaqiM -uO a ^iiiraxjJ .H oU*

Prof J. W;^4^*"^lS^ot>i-?m of Chlorir/e^dS^BBSi^^''^^, •-^^ith t$g'*]^M ^'Substitutions (with a VliUjl". ^K-V^ m Mr. T^^ Tfftiffi^'dn 6'il the Diffusion of Gases '.™ ,^"!^f ^^.-.^ M PM. ^?'K!^ Grove on Grotthus's Theory ofilMMM^i"'^

composition and Recompofeition ' . .V!.".'.\":* ^.^.^^f^?,r^.'.- . ' : "S^o^ Messrs. J. Schlossberger and'A-^JM^W^^^^I^^r^l^^^^^ Nitrogen contained in Alimentary Substances talieri froin B6tn "^ the Organic Kingdoms as a comparative measure of their Nik ' °^

tritive Power .'l'^^?.^".'-?^;^'^a

Prof. J. R. Young on the Evaluation of the Siitt?^°3f/NyutMl -.^'^^

•^Series , . .• v.^.^.".^K^^."i??'ak2

Dr. J. Stenhouse onik^ 'Oil produced bVMmigtf^fiWoffiffi;'^^' on Cinnamic Acid . . . V. ... ... . . liV. .'V?. .";° ^"P^{''7:ll?P,3B^

Mr. T. Graham's Note on the Existence of Phosphorip :AQif? w ..

Ir. i. (jrranam s i\ote on tae Jixistence oi fhosjahonp Acmin

the Deep-Well Water of the London Basin, .'f'".^!^??.-.^ : / 'W

Mr. W. De la Rue on a Crystallized Alloy of '2iiiaiTO£'fika™'\ , and Conti^ yjiujio / jifuojA no aiuoi. .T i. biij} •nwtwjl'i .a .eiaw^

Mr. A. W. Williamson's Experiments on Ozone . : .V^.^P. f^iil2 Mr. H. Hennessy's Researches upon the Connexion betvi'een

the Rotation of the Earth and the Geological Changes of its

Surface 376

Prof. C. F. Schoenbein on a Peculiar Method of obtaining the

Se^qui-ferrocyanide of Potas,si,um .,..,. . ..,,,5..^.^.,.,. -.vvrtiv ^r^"* Prof. C. F. Schcentie'ih oh tli^ mhirk ot Ozh\i€^ {^^^y. /!9.^Vf h^G

Proceedings of the Royal Society 390

On the Red ColOlir^bf'Lithai^ge.'by'M. Leblanc . . :':'<:{?l^. :4.?'^^^^ Analysis of the Silicate of Manganese from AIgiersi^'b^''^I?ft'3

Ebelmen .IH fVl'^A ^^}^?.^?.^P.'^: ."Pi^FP?^ .■^•40l^

On the Artificial Production- of- -Diaphanous Quai-tftl ^^Iftf .9^^ Ebelmen. ...... .'. }'^} .'^?^^Pt ^3*^, ^'.^H ^^99v .J^. .ypH 4^'

On the Artificial Production of Hydr^ffi,^^.3kiblih^.4i^4 iJrtl^ovements in Phbtt>ghii)hy }[^."}Wx Pf^P???:=^!{^^^^^^'}nW. /^ 4©^

QQiBiTiiNiisi oar jV4>uixxjfiiion'iUft'»'i«ni«:6)k vh

(Q^^ the Lighting of .Mine*.J*yj«ette8jQfetite; KfeUtrk/J^Wp. (L<*t6p>.)d4

^gteorolpgicaJ.Ob§Qryfitipns fpr^t^pfWaabmSilfi^ -^ ,bi»A. 3ia»ri(407 8f€ ....... .Tiible. ..... ^ ......»*».. % .. .. .. * .. K ., .. . 9ii«MJ8T."ia «x2'.(Ij»fl'§

818 laqqoO \o aJ^iaoA bns ^luoiaM lo obholilo[ia] ^o Jk8 aldooG

6fg iijoY in989i4 aili gnhub aifiil

ei8 St>81 J8ug»A lol saoilJi-nasJO IsoigoIoioaJsM



Mr. J, R. Hind on the Comets which have been discovered since

July 1844 . H.;^aMa:^0'^— .iX-XXJ.J Oiaai/tU^5 409

Mr. J, R. Hind on the Elements of several Comets not previ-

Mi. R. Laming s Observations on a paper by rrof. raraday con-

"c'erfting H^j^tr^p Q^pjpdAicHon and the Natuieof Matter .... 420

r. A. Cayley on tlie 'Transformcition of Elliptic Function s,.^.;,'^4

j^! T. HopVins on the Diurnal Changes of the Aqueous Pory",.:,-

•tioi\'pf die Atnaosphere. and their Effects on the Barometer 427

Brpf. J. W'. ^Draper's Account of ^9,^, remarkable difference be- ^ tween'^J:J^ Rays of Incan4e^^t'^ii}j.|^^^iai}4 those emitted %,.^.j]/: an Electric Spark . . -.tednci-rn^Jnamii/i i.r ;.--3niWiv-, t: -^35

Prof. 4R. Young on the %fe}?fi&,<|#f Afl^ftift^I^eutral

jj^nd Periodic Series .". . . tcr^oH-3*mi^'

ogLighting Mines ". ,4«2

j^Ohservations on tlie Discovery df the .^g5P9^Mxi?f no pof. C. F. Schcenbein s Kemarks on MrH. WBwnflQ»JtAr^?9?f-crJi

J^^srs. L. Playfair and J. P. Joule on Atomic Volume ^HfSgp-bxiii 2^*^. ?.''.^yi^y :; bnt.:.-^- :.:.-. •.:.•.:..•.:.• ^c{lvno?m£iili¥/-.W- .-A lM naswiad iioixannoO srii noqu eodmsessH a'^aaannsH .H .iM eJi I0 ga^asdO iBoigolosx) axfi bns dimS. adi \o aohsioH sdi

B'CP, , .TTTTTTT. sos'huB

9d:r gnxni^ldo lo borf;J9M imlunol xs no nigdna^rfoS .1 .0 .loil

068 ^is'pori IbvoH edi \o esnibgsooiSl

l\jI(9^rs."L. Playfair and Ji,p^j^.qy[1^9n^ti(aSHa%lHKS(^4.^%di xiO

cificj ^r^vity. (co?/.c/2«/f?4)tt sssxt/ygnxiM- ^a aJx.-j iliS sAi- ia •meyiiS^v r^rnJ- Stehhouse's Analyses of the Ashes of Sugar- Canea^^^eBftjy

the W^% Indies ,iwkfJK^7- -"k)- fn>iJcHj4x)n<i- im'iith'ik- 'jdi^^b

"P^^ Rev. J. Booth on a New Class of Properties of Line/|.^(^ja

{.(Surface§,cj^(1;Jie j^egond, Order flort^afee-jS 4flxoSii-f A- sdP^J

IJwf. E. Wartmann's^econd Memoir cffl(J#||l^^flq m^-JnarnQvo-^I



Mr. R. Moon on Fresnel's Theory of Double Refraction .... 553

Addenda to Mr. Drach's asserted Proof of Fermat's Theorem 560

On Respiration, by Prof. Magnus 561

Analysis of Titaniferous Iron 564

Analysis of Sphene 565

Analysis of Cascarilla— Cascarilline, by M. Duval 567

Spheroidal Condition of Liquids 568

Meteorological Observations for October 1845 569

Table 570

Index'. . ; 571


I. Illustrative of Mr. Warren De la Rue's paper on the Structure of Electro-precipitated Metals.

II. "t Illustrative of Dr. Miller's paper on Lines produced in the Prismatic

III. J Spectrum.

IV, Illustrative of Prof. Draper's paper on the Allotropism of Chlorine.

V. "I Illustrative of Messrs. Binney and Harkness's Account of Fossil Trees VI. J found at St. Helen's.

Errata and Addenda.

In the Meteorological Table for March (May Number), the average temperature observed at Sandwick Manse, Orkney, is stated to be 4840 instead of 3872.

Page 1:26, paragraph 2, line 2. On the left-hand side of equation (9.), for

X read t/.

... 286, line 2 from bottom, /or pm read p'^.

... 287, ... 13, the last -|- ought to be .

o<» " 1 xU, IS an exponent.

... 288, ... 9,f()rz y rcadz—y.

... 363, ... 2, the exponent should be ?j instead of M-f 3.

... 397, ... 18, /or venal read renal.


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jot -JOURNAL OB;,M£IMM:u^^«^^

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JULY 18i'5. "^JSHKO*.?^

I. On the Magnetic B.elation^'^^pqid^i'Qharacters of the Metals, By Michael Faraday, D.C.L.^ F.B.S.t Foi-eign Asso- ciate of the Acad. Sciences^ 'Si'C.'^^^ ivyni^ll .i\A U, -. ijiMt^i.iil A

IN two former communications to iRe.E^iiosppnicaflitaga-j, zinet I'especting- the magnetic characters of metals ge- nerally and the temperatures at which they respectively lost ; or gained the powers of magnetic induction, I said that iron, and nickel were the only metals which had this powers and . that I could not find it in pure cobalt. In this 1 was in error; cobalt has this property in common with iron and nickel, as others have said. I have sought for the piece of cobalt on which I experimented and believed to be pure, but cannot find it, and am now unable to ascertain the cause of my error, though not too late to correct it.

By favour of Dr. Percy and Mr. Askin I have recently experimented with two fine pieces of pure cobalt prepared b^^ the latter, both being well-fused and perfectly clean nlasse^f^. This metal becomes strongly magnetic by induction, either of - a magnet or an electro-current, and can easily be made to lift more than its own weight. Like soft iron and nickel, it does not retain its magnetism when the inducing influence is re- moved. ' r ■'/

It was to me a point of great interest to ascertain whether, and at what temperature, cobalt would lose this powej^ ,^nd . become as the unmagnetic metals. To my surprise I found this to be very high, not merely much higher than with nickel, but far above that required for iron or steel, and nearly ap- proaching the temperature of melted copper. That for iron is a moderate red heat, and that for nickel the temperature of boiling oil only. As the temperature rises, the magnetic force of the cobalt continues, apparently undiminished, to * Communicated by the Author, t 1836, vol. viii. p. 177, and 1839, vol. xiv. p. 161. Phil. Mag. S. 3. Vol. 27. No. 177. My 1845. B

2 Prof. Faraday on the Magnetic Relations of Metals.

a certain degree of heat, and then suddenly ceases ; and it comes on as suddenly in descending from still higher tempe- ratures.

The oxide of cobalt procured by burning the metal cobalt on charcoal by a jet of oxygen was obtained as a fused glo- bule and was not magnetic.

The oxide of nickel being heated and cooled is not mag- netic, but whilst heating care must be taken that it is not re- duced. If heated in the flame of a spirit-lamp, especially at the lower part, it will often appear to be not magnetic, and then as the temperature falls will become magnetic ; but this is caused by the reduction of a little of the oxide at the edges or elsewhere in the mass to the metallic state, and its exhibi- tion of the properties of the metal at temperatures above and below the magnetic point.

Manganese. A piece of manganese prepared by Mr. Thomson and considered pure was put into my hands. It contained a trace of iron ; it was very slightly magnetic, and probably only in consequence of the little iron present. Before a jet of oxygen or charcoal, it burnt with sparkles somewhat in the manner of iron, and produced an oxide which could be obtained either as a porous white mass or as a dense compact brown mass, translucent in small slices; but in neither state was the oxide magnetic.

I then cooled* manganese, chromium and many other metals and bodies to the lowest temperature which I could obtain by a mixture of aether and solid carbonic acid placed i7i vacuo-\, the temperature being then not higher than 156° F. below 0°, but not one of them assumed the magnetic state. The following is a list of the substances:














Iridium and Osmium. Antimony. Arsenic. Bismuth. Fusible metal. Speculum metal. Plumbago. Gas- retort carbon. Kish. Orpiment. Realgar.

Sulphuret of antimony, bismuth.

* Phil. Mag., 1839. vol. xiv. p. 162.

f Fhilosopbical Transactions, 1845, pp. 157, 158.

On the Products of the Distillation of Benzoate of Copper. 3

Chloride of silver.

lead. Protoxide of arsenic.

antimony, lead. Oxide of bismuth. .,. tin (native).

manganese (native).

Sulphuret of copper.




tin. Carbonate of iron, native. Prussian blue.

Crystallized sulphate of iron. Calomel.

Thus it appears that only iron, nickel and cobalt are mag- netic, or can be made magnetic amongst metals after the man- ner of iron; but the addition of cobalt, and still more, the very high temperature required to take away this property from it, increases the probability* that all the metals form a common class in respect of this property; and that it is only a difference of temperature which distinguishes these three from the rest, just as it also in a similar respect distinguishes them from each other.

In connexion with the effect of heat it may be remarked (and perhaps has been remarked already), that, assuming an elevated temperature for the internal parts of the earth, then it is evident that at a very moderate distance from the surface, as compared with the earth's tliameter, the substances compo- sing the earth must be destitute of such magnetic power as is possessed by a magnet; and, at a distance somewhat greater, none of them can retain even that power which soft iron has of becoming magnetic by induction. In such case, whether the earth be considered as magnetic of itself, like a loadstone, or rendered magnetic by induction under the influence of exter- nal magnetic masses, as the sun for instance ; still it can only be in its crust that the magnetic power could be developed. Assuming with Ampere, that the magnetism of the earth is due to electric currents circulating around it parallel to the equator, then of coui'se the above observations regarding the effects of heat would not apply. Royal Institution, June 7, 1845.

II. On the Products of the Distillation of Benzoate of Copper, By John Stenhouse, Ph,D.\

EAR the conclusioHrol^ Dr. Ettling's very able and ela- borate paper on the- Essential Oil of Spirea Ulmaria and Salicylous Acid, which appeared in Liebig's Amialen for 1840, it is shortly stated, lhat^5y the destructive distillation of

» Phil. Mag., 1836, vol. viii. p. 177. 'I' Communicated by the Author. B2


4 Dr. Stenhouse the Products of the Distillatioji

salicylite and benzoate of copper, Dr. Ettling had obtained among other products two neutral crystalline bodies that from benzoate of copper having a smell very much resembling the odour of the geranium. Being quite unaware that Dr. Ettling had, subsequently to the publication of that notice, analysed the compound from the benzoate of copper, I was induced a few months ago also to prepare a quantity of that substance and to subject it to examination. Having men- tioned this circumstance to Dr. Ettling, he very kindly fur- nished me with the subjoined account of his experiments, and at the same time requested me to prosecute the examination of the subject.

" A quantity of benzoate of copper consisting of a mass of small, slightly soluble needles of a greenish-blue colour, ob- tained by mixing hot solutions of benzoate of potash and sul- phate of copper, was heated in a retort placed in an air-bath to about the temperature of 220^ R. The retort was furnished with a tubulated receiver and a pneumatic apparatus to collect any gases which might be evolved. The salt became first brown and then of a reddish copper colour, giving off at the same time an oily matter, a portion of which crystallized in the neck of the retort, while a light oil passed into the receiver, where on cooling it also became filled with crystals. A gas passed into the pneumatic apparatus, which, as it rendered lime-water turbid and was absorbed by potash, was evidently carbonic acid. A second portion of gas was also evolved, which burned with a blue flame and was not absorbed by pot- ash. It was not more closely examined. The mass of salt in the retort diminished to about half its bulk, and when still more highly heated gave out an oily liquid, which on cooling crystallized in needles. If the distillation was carried still further, the retort was found to contain a little of a brownish- coloured salt of copper mixed with a quantity of metallic copper.

" The solid portion yielded by the distillation had a greenish colour, was hard, brittle, melted readily, and it, as well as the more fluid portion, had very much the smell of naphthaline, though also faintly reminding one of tlie odour of red gera- nium. When the products of the distillation were heated with a weak solution of potash, a portion of them dissolved, forming a yellow solution, while another swam on the surface of the liquid as a colourless oil, which on cooling became a crystalline mass resembling paraffine. This crystalline portion was repeatedly treated with alkaline leys, by which operation

of Benzoaie of Copper. 5

its bulk was exceedingly diminished, and probably a consider- able quantity of it decomposed. The portion insoluble in al- kalies dissolved very readily in hot alcohol, and crystallized on cooling in long snow-white crystals. These were melted and subjected to analysis in the usual way.

"I. 0'581 grm. gave 1*675 carbonic acid and 0*265 water. "II. 0-5655 gave 1*633 carbonic acid and 0*258 water. I. II.

Carbon . 78*55 7^*76

Hydrogen 5*06 5*06

Oxygen. 16*39 16*18

100*00 100*00

" When that portion of the distillate which dissolved in the potash-ley was boiled in a retort, water passed over mixed with a few drops of an oily matter, which was not more closely examnied. What remained in the retort, on being saturated with sulphuric acid, became a mass of shining crystals, which closely resembled benzoic acid. When the brownish-red co- loured salt which remained in the retort was treated with sul- phuretted hydrogen gas, it became very hot and was covered with a sublimate of white crystalline needles, while hydrogen gas was given off and sulphuret of copper remained. This sublimate was soluble both in alcohol and water, and crystal- lized on cooling in long shining needles, having a strong acid reaction and an appearance quite different from that of ben- zoic acid. The acid can also be extracted from the copper salt by means of ammonia. It readily crystallizes when the ammonia is saturated with acetic acid, and the copper is preci- pitated by sulphuretted hydrogen."

The quantity of the neutral crystalline compound which I subjected to examination was obtained from benzoate of cop- per prepared exactly in the way already described by Dr. Ettling. The dried salt was distilled in a copper retort over the naked fire. The amount of the neutral body which the salt yielded was pretty considerable ; it came over in oily drops which condensed into a pasty crystalline mass as the receiver cooled. The products of the distillation were benzoic acid, the neutral crystalline body, and a small quantity of a heavy oil, in appearance and smell much resembling benzone. The pasty mass was first strongly pressed between folds of blotting- paper to remove adhering oil. The crystals were then re- peatedly agitated with a hot solution of carbonate of soda in great excess, which removed the benzoic acid, the amount of which considerably exceeded that of the neutral body. It is

6 Dr. Stenhouse on the Products of the Distillation

improper to employ a solution of a caustic alkali to remove the benzoic acid, as such a proceeding would certainly destroy a large proportion of the neutral compound. The crystals were next collected on a filter and washed with cold water till every trace of alkali was removed. They were then dissolved either in hot alcohol or in aether, in both of which liquids they are exceedingly soluble, and were purified by repeated cry- stallizations. They crystallize out of aether in large four-sided oblique rhombic prisms. The crystals are hard and brittle, and grate between the teeth like sugar. They have a faint aromatic smell, somewhat resembling that of the geranium, but when heated approaching that of lemons. When slowly deposited from an aethereal solution, the crystals may be rea- dily obtained an inch in length. Their melting-point is 70° C. After they had been kept melted for some time, to drive off any adhering aether, they were dried in vacuo over sulphuric acid and subjected to analysis.

I. 0*3508 grm. substance burned with chromate of lead, gave 1'024<2 cai'bonic acid and 0'161 water.

II. 0*3902 gave 1*1437 carbonic acid and 0'182 water.





Carbon . 14





Hydrogen 5





Oxygen . 2





1313-39 100*00 100*00 100*00

It is evident from these analyses that this compound con- tains only one atom of oxygen less than benzoic acid, the for- mula of which is Cj4 Hg Og, and consequently it is isomeric with benzile. It differs very essentially from benzile, however, for when it is heated with solid potash it is immediately con- verted with evolution of hydrogen into benzoate of potash ; while benzile, when similarly treated, yields, as is well known, benzilate of that alkali. When treated with an alcoholic so- lution of potash, it quickly forms benzoate of potash without any change of colour, while at the same time a little benzoic aether is also produced. When it is boiled with an aqueous solution of potash or soda, it is also converted into benzoic acid, though more slowly ; and a portion of the compound is apt to distil over undecomposed. A quantity of the acid ob- tained by decomposing the neutral compound with an alkali in the way just described was purified by repeated crystalliza- tions and subjected to analysis.

0*3807 grm. substance, dried at 100° C, gave 0*9575 car- bonic acid and 0*1698 water.

of Benzoate of Copper.




Carbon . 14

1 050-00



Hydrogen 6




Oxygen . 4







The silver salt was prepared by double decomposition. The ajjpearance of its crystals was exactly that of benzoate of silver.

I. 0-4287 grm. salt dried at 100° C, gave 0'202 metallic silver = 50-67 per cent, oxide.

II. 0-6175 salt gave 0*289 silver = 50-33 per cent, oxide. The calculated quantity of oxide of silver in the benzoate,

with the atomic weight of carbon at 75, is 50-68 per cent.

The neutral compound dissolves in sulphuric acid with the assistance of heat; the solution has a greenish-yellow colour. Nitric acid also i-eadily attacks it and converts it into benzoic acid.

Action of Chlorine on the neutral body.

The compound was kept melted in a tube, and a stream of dry chlorine gas was sent through it for six days till it was completely saturated. It soon assumed a deep yellow colour, and retained a semifluid consistence at an ordinary tempera- lure, thus evidently consisting of a mixture of a liquid and a solid crystalline substance. When cooled down to nearly 32° F. it became quite solid. Its smell was exceedingly pungent and offensive, bringing tears into the eyes very readily. The pasty mass was gently heated for some time to remove adhe- ring chlorine, and then dried in vacuo over sulphuric acid and quicklime.

I. 0*3765 grm. substance, burned with hydrate of lime to determine the amount of chlorine, gave 045 15 chloride of silver = 29'59 per cent, chlorine.

II. 0-3144, burned with chromate of lead, gave 061 6 car- bonic acid and 0-0916 water = 53*43 percent. C. and 3*23 H.

As the substance analysed was evidently a mixture of two compounds, I proceeded to separate them by pressing the pasty mass between folds of blotting-paper, which absorbed and removed the greater portion of the fluid body. The solid portion was then repeatedly dissolved in anhydrous aether, in which it was very soluble. On the evaporation of the aether, it was deposited in large flat shining crystals, which had a very faint smell, not at all disagreeable, and somewhat resembling that of the solid chloride of carbon, though not so strong. When sublimed, it formed flat four-sided prisms, which were iridescent like the crystals of chlorate of potash. Its melting-

8 0)1 the Products of the Distillation of Benzoate of Copper.

point was very high, being 87° C. It was kept meUed for some time to drive off any adhering aether, then dried under the air-pump and subjected to analysis.

I. 0*316 grm. gave 0*7658 carbonic acid and 0*114 water.

II. 0*321 gave 0*7755 carbonic acid and 0*1116 water. HI. 0*3805 gave 0*9183 carbonic acid and 0*1408 water.

IV. 0*2122 gave 0*1380 chloride of silver = 16*04 chlorine.

V. 0*2505 gave 0*1675 chloride of silver = 1649 chlorine.

VI. 0*177 gave 0*1155 = 1609 chlorine.


Carbon . 66*09 65*88 65*87

Hydrogen 4*00 3*86 4*11

Chlorine. 16*20 16*20 16*20

Oxygen . 13*71 14*06 13*82

100*00 100*00 100-00

The substance employed for these analyses was prepared at three different times. I am sorry to say, however, that I have been unable to deduce any probable formula from these analyses.

When this crystalline compound is heated in an alcoholic solution of potash, benzoate of potash, chloride of potassium with a little benzoic aether are immediately formed, the colour of the solution becoming at the same time of aji inky blackness. When this alkaline solution is treated with an excess of mu- riatic acid, the benzoic acid precipitates on the cooling of the liquid. The benzoic acid is mixed with a good deal of a dark- coloured tenacious semifluid resin, which has a strong empy- reumatic smell, exactly similar to that of creosote; so that chloride of potassium and benzoic acid are not the only pro- ducts of this decomposition. The benzoic acid was purified by repeated crystallizations and subjected to analysis.

0*1572 grm. gave 0*3986 carbonic acid and 0*0734 water. Found. Calculated.

Carbon . 69*15 68*85

Hydrogen 5*19 4*92

Oxygen . 25*66 26*23

100*00 100*00

The liquid chlorine compound already mentioned can rea- dily be dissolved out of the bibulous papers by treating them with aether. The liquid compound however always retained a considerable quantity of the crystals dissolved in it, just as oleine does margarine or stearine in the fats, so that I was quite unable to purify it. This is much to be regretted, as it ap- peared to be much the more interesting of the two, as it is that which possesses the very pungent smell already mentioned.

Mr. G. G. Stokes on the AberratioJi of Light. 9

When the liquid compound was treated with an alcohoHc so- hition of potash, it was also resolved into benzoate of potash, chloride ofpotassium, and a similar resinous matter, the quan- tity of which appeared to be even greater than that yielded by the solid compound.

Neutral benzoate of lead, formed by adding a solution of benzoate of soda to acetate of lead, was also subjected to de- structive distillation. A small quantity of benzoic acid came over mixed with a little of an aromatic oil, the smell of which was quite different from that yielded by benzoate of copper. I was unable, however, to detect the presence of any neutral crystalline body.

Glasgow, May 12, 1845,

III. On the Aberration of Light. By G. G. Stokes, M.A., Fellow of Pembroke College, Cambridge"^.

nPHE general explanation of the phaenomenon of aberration ■■ is so simple, and the coincidence of the value of the ve- locity of light -thence deduced with that derived from obser- vations of eclipses of Jupiter's satellites so remarkable, as to leave no doubt on the mind as to the truth of that explana- tion. But when we examine the cause of the phaenomenon more closely, it is far from being so simple as it appears at first sight. On the theory of emissions, indeed, there is little difficulty ; and it would seem that the more particular expla- nation of the cause of aberration usually given, which depends on the consideration of the motion of a telescope as light passes from its object-glass to its cross wires, has reference espe- cially to this theory ; for it does not apply to the theory of un- dulations, unless we make the rather startling hypothesis, that the luminiftrous aether passes freely through the sides of the telescope and through the earth itself. The undulatory theory of light, however, explains so simply and so beautifully the most complicated phsenomena, that we are naturally led to rega. I aberration as a phaenomenon unexplained by it, but not incompatible with it.

The object of the present communication is to attempt an explanation of the cause of aberration which shall be in ac- cordance with the theory of undulations. I shall suppose that the earth and planets carry a portion of the a3ther along with them so that the aether close to their surfaces is at rest rela- tively 40 those surfaces, while its velocity alters as we recede * Communicated by the Author.

10 Mr. G. G. Stokes the Aberration of Light.

from the surface, till, at no great distance, it is at rest in space. According to the undulatory theory, the direction in which a heavenly body is seen is normal to the fronts of the waves which have emanated from it, and which have reached the neighbourhood of the observer, the aether near him being sup- posed to be at rest relatively to him. If the aether in space were at rest, the front of a wave of light at any instant being given, its front at any future time could be found by the method explained in Airy's Tracts. If the aether were in motion, and the velocity of propagation of light were infinitely small, the wave's front would be displaced as a surface of particles of the aether. Neither of these suppositions is however true, for the aether moves while light is propagated through it. In the fol- lowing investigation I suppose that the displacements of a wave's front in an elementary portion of time due to the two causes just considered take place independently.

Let u, V, w be the resolved parts along the rectangular axes of j:", y, s, of the velocity of the particle of aether whose co- ordinates are x, j/, z, and let V be the velocity of light sup- posing the aether at rest. In consequence of the distance of the heavenly bodies, it will be quite unnecessary to consider any waves but those which are plane, except in so far as they are distorted by the motion of the aether. Let the axis of z be taken in, or nearly in the direction of propagation of the wave considered, so that the equation to the wave's front at any time will be

z = c + vt + i;, (1.)

C being a constant, t the time, and ^ a small quantity, a func- tion of ^, y and t. Since n, u, w and ^ are of the order of the aberration, their squai'es and products may be neglected. Denoting by a, /3, <y the angles which the normal to the wave's front at the point {x,i/, z) makes with the axes, we have, to the first order of approximation,

^°-^"=-^' "^^^=-z|' <^^'^=^-> ' (2-)

and if we take a length V dt along this normal, the co-ordi- nates of its extremity will be

If the aether were at rest, the locus of these extremities would be the wave's front at the time t + d t, but since it is in mo- tion, the co-ordinates of those extremities must be further in- creased by ?^ rf ^, vdt, wdf. Denoting then by ^', y, 2' the co-ordinates of the point of the wave's front at the time t + dty

Mr. G. G. Stokes on the Aberration of Light. 11

which corresponds to the point (j!',y, «) in its front at the time t, we have

.^' = 5; + (to + V)dt\

and eliminating .r, y and z from these equations and (1.), and denoting t, hyj'{x,i/, i), we have for the equation to the wave's front at the time t + dtj

z' -{w + N)dt=C + Yt

+/{^ - - v^^) dt, y - (. - vg) dt, t},

or, expanding, neglecting dt'^ and the square of the aberra- tion, and suppressing the accents of sc, y and a,

s = C + Yt + \;, + {w + Y)dt. . . . (3.)

But from the definition of ^ it follows that the equation to the wave's front at the time t -\- dt will be got from (1.) by put- ting i + d t for tf and we have therefore for this equation^

z=C + Yt + i;+[Y + ^Jdt. . . . (4.)

Comparing the identical equations (3.) and (4.), we have

7^ = TO. d t

This equation gives ^= / tadt: but in the small term ^

we may replace / wdt ^y =rr / lodz: this comes to taking

the approximate value of z given by the equation z = C + Ytf instead of /, for the parameter of the system of surfaces formed by the wave's front in its successive positions. Hence equa- tion (1.) becomes

z=C + Yt + y/*'^^^'

Combining the value of ^ just found with equations (2.), we get, to a first approximation,

TT 1 /*dw , - TT 1 PdW , ,^ .

2 YJ dx ' ^ 2 VJ dy ' ^ ^

equations which might very easily be proved directly in a more geometrical manner.

If random values are assigned to u, v and to, the law of