POI. XXIX., h'o. 1.1 HOWARD-THE HEAT OF CHEbLICAL REACTIONS. &a 3

05cial Notices.

NEW EON. FOREIGN SECRETARY AR'D VICE- PRESIDENT.

3)r. Rudolpli RIcssol lins boon nppointcd Hon. Foroign Secretory of tho Socioty in tho plnccof tlioluto Dr. Ludwig RIond, F.R.S.

Prof. A. Licorsidge, F.R.S., lins been appointed n Vice- b s i d o n t of tho Society in tlio plnco of Dr. R. Rloss~l, appointed Ron, Foreign Secretmy.

NXW HON. SECRETARY OF THELONDOR' SECTION, blr. J. H. Costo, of "Utopin," Glouccstor Rood,

TcJdington, hns bccn nppointcd Eon. Sccrelary of the London Section in tlio plnco of Mr. Julinn L. Bukcr, wlio Iins rcsigncd oflico.

Canadian Section.

UB. w. LASll ~ l l l . L l ~ I i 13. TII): CIIAIII.

__- THX CHYSTALIJSATTON O F CANE SUGAR;

ny c. B. U A I ~ ~ O R B .

New England Section.

111' 1INXltY ll~\\"$ltl).

Ted oj /icniittg sitl?~liiiric ucid.-Thu old-fusliioncd inotliod of anulysin funiing eulpliuric ncid by titruuting wit11 a iiorniul udPi so~iition is not nb ~ I I sirtitifactory for rugulur tochniciil usc, particularly by tho forcinnii of nn ncid worlis, for tho roiison tliiit n vury slight orror in tho strongth of tlio solutioii 01' in tho quuntitios of tho iiiatoriula usod cnusus u sorious orror iii 1110 pcrcontngo of froo sulpliuriu niilipdridu. Wo found in our p h n t tliiit i t \YUS oxtronioly tlinicult t o got c o ~ i c o ~ d ~ i ~ i t rosillts unloss tlioso titrations woro mndo by tliu clion~ist. As i t is not pructicnhlo to liuvo tlio cliumist on liund dny iiiid niglit, und us control nnnlysos liavo to lo inndo onco un hour 011 sovorul kinds of acid, it is most iniportant to Iiaw a rclinblo niiti simi)lo mothod. I togan t l iu work on my now motliod in tlio wintor of 1008, nnd hsoo had it in rcgiilur opcrution cvor sinco tho early spring of tliut yonr. Tltu priiicipla involvcd is tho munsuromont of tho lioat dosolopcd Iiv coubining tho frco sulpliurio unliydrido with witor. tis this h u t vnIiio is w r y grout, rory siiiuU vurintioue in 1110 urcontngo of froo unliydridu miilto Iurgo variations iii tliu loat produced. 111 ardor to oliniinntu its fur us possib~o tho liout of dilutioii of sulphuric ncitl, 1 profcr to talto us my 8ouffio of wtrter for hydrating tho unhydrido, a sul. phario ncid of suoii couconbrulion, tliut wlion a givon

quantity of this ncid is mixed with nn oqual woight of fuping acid. tho rosulting mixtun, will only contain s1lglltly morc wntcr thnn is neccssary to produco tho monohydrntc. Jn prnctisu whcro a funiing ncid of 20 por ccnt. to 25 pcr cciit. of frco nnliydridu is to bc tcstcd. I 1160 for mixing wit11 i t a sulphuric ncid contnining 92 per colt of H,SO,. I t is, of COUIBO, importnnt to cnrry out the niinlysis in a VCSEC~ EO urrnnged ns to prevont the loss of licnt by rndiutioii: For this purposo 1 Iinvo found a Uownr wmivm tubo to bo niost sutisfnctory. Tho drop in tcm- pcrnturo through rndintion when win ono of thcso tubes docs not matcrinlly nffcct tho rcsuft witllin tho time rcquircd for nnnlysis. In dotnil my mothod of pro- ccduro is us follows :-

100 grms. of tho fuming acid to bo testcd aro wcighcd in n Downr vncuum tube. Tho tompcrnturo (a) is notcd. and tlicn tho tcnipornturo (b) of tlio rcngeut acid, aftor wliich 100 grms. of tlio 09 por ccnt. ncid nro poumd into tho Dowar tubo nnd thorOUgldy mixed by slimiig with tlio fuming acid nlrondy in tho tubc. Tho tompumturu (0 ) of tlio mixturn is rccordcd. The h u t of reaction cyuob o -+I muking uo iillowonco for tho hcnt capncity of tho Dcwnr tubc. In ordor to avoid comctions for tho heat capacity, or any othor small cmra which might creop in, tests am mado in this xnnnnor of fuming ncids, tho composition of which is ornctly known, and from thcso iiiitinl dctorminntions n tnblo is propaEd. A'ote: Vncuum tubo Xo. 7145, 100 mu. x 45 mm. dinmotor, sold by Eimor d: Amond, is a convonient sizo and shpo to uso

-

IIent of renctlon. F.

72. 75.2

76.8

74.4 76.6

78.0 78'2 80.4 81.0 8"-.8 84.0 85.2 80.4 87.0 86.6 00.0 01.2 02.4 99'6 91'8 06.0 07.2 08.4 QO.0

1OO.8 102.0

Free sulphurla anhydride. Per cat.

21.0 21.2 21.1 21.0 21.8' 22.0' 22.2' 22.4 22.0 22.8 23.0 25.2 23.4 23.6 2343 24.0 24.2 24.1 24'0 24'8 56.0 26.Y 26.4 26.6 2C8 20.0

It will bu notcd from tho nbow tablo that thorn is a difforonco of OD I?. for uncli pcr cont. inorcnso of fro0 unliydrido, und us rondings may l o do ondcd upon, ovon with tliu simplu uppurntus used, to i c d i n 4" F.,it will Im BCCIII tha t tlio rcsultti obtnincd slioiild bo ostronioly nccurntc. Tlioy nru, moroovor, cnrricd out vcry ousily by nn ordinury into ligont workmnn ; tho timu roquirctl for tho dotor- iiiintrtion should not ovcrcd 3 or 4 niinutos from tho shrt LO tho finish.

!l'out of ~ttonoHydrule.-'l'ho tia~no princi do mc~y bu usod 10 givu a inost uccurutu tiutcrniinntion oj tlio stmngtIi of aulphuic mid running froin 98 pur cont. to 100 por cont. li.SOJ, but, of cour~o, in ninkin this tast tlio funiing ncid IlGst bo used in osccss, unci tf,o licnt dovolopcd is tho luonsuro of tlio aniount of uncoinbiiiod wntor contninod ,11 tho sufpliuria acid which liuti boon tcstcd.

For tho rcugoiit acid is uscd ordinary fuming acid of z.1: pi^ curit. t o 2B pcr cciit. uiihydrido, and witli this [u~iinig acid a sulpliuric ucid niay bo tostod rovidod i t Jontuinti from 0.1 por cont. to 100 pcr ccnt. %,SO,. If w r k u r ucids arc to Lo U E U ~ , a fuming acid containing tiioro niiliydl.ido would bo proforaldo. Tho uiinlysis IS xrrricd out as follows :-lo0 grms. of tho suuiplo of ncid rn bo tostcd nro woigliod into a Dowar vnouuni tubo und t11o tonipcrnturo (a) notcd. 100 grms. of tho fuming roiigunt wid; tho tuniporaturo (b) of nliicli has boon notutl,

p a