AN APPARATUS FOR THE MEASURE- MENT OF THE PARTIAL VAPOR PRESSURES OF THE BINARY SYSTEM AMMONIA- WATER ARNOLD O. BECKMAN THESIS FOR THE 13KGKEEOFBAGHELOROF SCIENCE IN C liEMICAL ENGINEERING c;OLLE(JE OF LIBERAL ARTS AND SCIENC^ES ITNIVEKSITY OF ILLINOIS 1922 X 'X .C tC UNIVERSITY OF ILLINOIS __A_ugusi._l.Q_-_i923__. THIS IS TO CERTIFY THAT THE THESIS PREPARED UNDER MY SUPERVISION BY _A r n Q_1 d_ _Qr_v i_l 1 8. _ Be c kman ENTITLED Aipparatus for the Measurement of the Partial y_§P_QP_ _ Pil® s_3u_r e ?_ _ p_f _ _t he_ _ B inp-ry _ Sx§ t_® m r_»_ IS APPROVED BY ME AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE DEGREE OF ___BacJae_lo 2 i_p_f __ScjLence_ Instructor in Charge Approved : head of department of * ' t... J w ■ A- Digitized by the Internet Archive in 2016 https://archive.org/details/apparatusformeasOObeck Table of Contents. I. Introduction 1 II. Historical 3 III. Theoretical 5 Diagram of Apparatus 7 IV. The Apparatus 8 V. Calibration 13 VI. Operation 17 VII. Summary 19 VIII. Acknowledgments 20 IX. Bibliosraphy 21 1 1 •• \ RiTT 't. 4 1 # . 4 . j * . . - . .=Xi.3ijTiri .-U - ^ .’^i r '.iMi- - ? .[ 1 I. Introduction. The measurement of the total and partial vapor pressures of aqueous ammonia solutions was undertaken primarily for the purpose of obtaining new data for use in connection with the absorption system of ammonia refrigeration. In developing the thermodynamic relations of the properties of ammonia solutions to be used in this work, it was found that the data available was neither sufff“iciently accurate nor extensive enough in its scope to permit of satisfactory mathem*atical treatment. There was an urgent need for accurate determinations of the vapor pressures of ammonia solutions v/hose concentrations ranged from 0 to 50 percent at temperatures of O'^to 120* C. From a theoretical standpoint the determination of the partial pressures should prove very interesting. The anom- alous behaviors of both water and ammonia are demonstrated in many of their properties and it is reasonable to expect a sim- ilar non-conformity with the laws governing vapor pressure. From accurate measurements of the partial pressures, the dev- iation from Raoult's and Henry's laws could be expressed. Since the determination of the partial pressures involves a measurement of the total vapor pressures, it v;as decided to carry out both determinations. The problem undertaken, then, was one of designing an apparatus which would perm-it the determination with a high degree of accuracy of the total and partial vapor pressures of aqueous ammonia solutions of all concentrations over a I CJ ' ■ ■■ ' ' 7 .' ■. ;j . . ■ • ‘ - •:> ’ ,1 '■ r.'i r, . vj t' . ' T' • 'rr . C 'f ^ frr pif , ^ ‘U ••* : • ' inn ' - ■ ' . I ' ,I ’ , 1 L- f?:*‘ '•y-- r- '!■ ( ' ' - f* f ^ ^ . 4 . , , I r ‘ ** • • » ■i 'J J ^ '-’Xi 7 . ■ : ■ / j ■, ‘ '>1 . I u. t .■> 'r' :e ■’} J:} . \: 'i , 'V-' ; . u \ . ')}>.• ni ,1 ^ ■ '^ f'.' '? Y;,U •' ■ • ■■ • 'f' -■'“' Xi'/'T- ’ ' 'o ; d 1 ; T' •• ■ •■I '■'■'7 .7 « ^ )i « ■ •r:'"-; Kfr'i**! T ‘ 0 -'; ' j»*» k , rr. 1 > , I .f '>fc ‘i>j Ah ' 0 I ■ il O; ; •* — I . ^ lo <•(.' ' ; • :i:;.'‘; ■' I^AX , f .. Ju- •■■ i^:i- rc Xit'r-i!itn?iii ' I' « - ' f f 'V’/'^ncct jfXx; ;.')■ 3,u'i*-7’ 'c'' ' ^; t: .-■ .- < t-m . (: kJAi 2 temperature range of 0° to 120*^0 , and a pressure range of app- roximately 15 to 800 cm. of Hg (l/5 to 10 atmos , ) , these limits being those met with in actual refrigerating practise and suf- ficient in extent for the theoretical considerations. .; ■% «e^i?t'fjLX ^o-*/ft os Osi.^ix 'iu; r)os%V ^ f ' -T4lrtife^ ft'ic^lT(ti#iT •X.ffrr^oi»-'Ax. Jan ■f . ■ . -. ' ■ , ' v' ‘ '..• ■' :' Vv ^: ■;,_ V ■’■ ils''* *' '■' i '•'^'■'^''T -i- . ’'■ ‘ ''s3' ' ''a^«i <■’ IS • <1 ' i t , ■ ■ 'f'-^' rr- 'V 's* .;V ■ .»,'. 4 , . , I'Vv , j !H,ri K^-4 5^1^ '04'- ta::. : '7 •• * ' • ■' i% .,:! ;,'r < ‘V'xf? • • «P ■ •i>,v,!f .‘,»-.‘*v • ‘.,v.f-‘ L ^."*> * j*t ’-I, .* ' *!' V*- ' •■■ • ‘T-'s® ,4-»V^ >■ *■'> 5#A *31 '4^*' *J*^ ^ ' V '4 II. Historical, 3 . The first determinations of the vapor pressures of aqueous ammonia solutions which were of any importance v/ere those obtained by Slms^ in 1861* He determined the total vapor pressures by the static method at the tem.peratures of 0**, 20° 40^ and 100° C, He employed only very dilute solutions in his work. 2 3 4 Perman ' * S in 1903, was the first to make measurements over any considerable ran^e of concentrations, v/orking with solutions containing 0 to 22,6 percent of amm.onia at temperatures of 0** to 60'*C., no pressures higher than 535 mm. of Hg being measured, however. He used a dynamic m.ethod which consisted of blowing air through ammonia solutions under certain condij^tions , then from the composition of the resulting vapor calculating the partial vapor pressures of its constituents. This method is not applicable to high concentrations, however, because the ratio of the airmionia content to that of the water in the vapor drawn off becomes so great that the results are inaccurate. Even at the concentrations used by Perman the results did not check very well, Perman ’s v;ork, also, is based upon several assumptions of rather doubtful validity (as the statement that Raoult’s law holds for ammonia solutions) that his results, while seem.ing to check fairly w'ell with themselves, must, never- theless, be looked upon with suspicion. The most recent, and to this date, the most reliable data 5 is that secured by Hilde Mollier in 1908, working in the labor- atories at Kdnchen. Her report included values of vapor press- I ** 'w - ' .' ':C*?-? / .•■/■, > "‘r - ; -.V -‘^ ••, - •'•'■ : * '" i" ' • J ■• . J . • ‘ f< .) ‘3 . . ■ ! .‘ * ^ ’ .'■ ’^7'’ c,..r •, • '. •wjr' V '■’ 'S'^Vc ^ -> J - J •■f A W 1 .^v» > ^ , # V/ t- i.< ■ •■ . *0 "if I • "’v .. #f(. > ■• - ttijrAij-r" ,i f N ' T' r . ■ > ' , •^3'TOrM . '■!:^-1f{ . '-' ••• = ‘ ■ 0 1 .''t :j :r • trj /'■'T •:>d t1 A' ,.■ . i '•#S,i' . •jrnA ■ , - . . " ■ ■''■ f ■. '■■ J‘ •“■ ■ •■ •'-.’f.! •-• ';i ' ' P>f.T • , rro-w^ - - •"•>'■ 4 ures up to 700 cm. of Hg ( 9,2 atmos.), at temperatures of 0** to 120^ C., and concentrations of 11.80, 23.39, 33.73, 41,55, and 50.31 percent. The method followed v;as the usual static method in which the pressure above the amjnonia solution contained in a closed vessel surrounded by a constant -temperature bath was measured by an open manometer. From the data siven in her report hov/ever, it is seen that the analyses of the ammonia solutions do not check v/ithin the desired degree of accuracy. Moreover, her work affords only the total vapor pressures. JP-' tT.'r', vl.»- . • . 5 III. Theoretical. The usual method of obtainlne the partial vapor pressures of any substance in solution is to assume that Raoult’s law holds and then to calculate the partial vapor pressures from the total vapor pressures and the com-positions of the solutions. In this case, however, since it is desired to show whether or not Raoult’s lav/ does hold for aqueoLis amjnonia solutions, the law cannot be used in the calculations. Since, then, the partial vapor press- ures cannot be calculated from a knowledge of the composition of the liquid phase, some method must be devised whereby the vapor phase miay be analyzed. Then, knowing the composition of the vapor, the total vapor pi^essure, and the vapor pressure of water (from Landolt-B8rnstein) , the application of Dalton's law will Give the partial vapor pressure of the ammonia. In order to make possible an accurate analysis of the vapor phase, it is desirable to have a large quantity of the vapor for analysis. Consequently, the apparatus should be designed with a com.paratively large space for the vapor phase. Since samples of both the vapor phase and the liquid phase are to be rem.oved for analysis, some arrangement should be in- corporated whereby the com.position of each phase will not change while the portion of the other phase is being removed. This could be done by separating the two phases after equilibrium has obtained and the total vapor pressure determined. In order to permit the use of hie:hly concentrated solutions v;ith their accompanying high vapor pressures, it seems advis- able to prepare the solutions v/ithin the apparatus itself. As * l' • • - r. ;v,; .■ ; , ^ ' *'- or-'O-r. • r||hri‘:'CJ C ,■ v ' ' ! • >J .' : < .TP •t . aoc •' . <• • . • I 6 coFjnercial ammonia can be obtained with a hieh degree of purity, it could be used for this purpose. As ordinarily sold in tanks it is under a pressure of approximately 10 atmospheres at room temperature, so that the ammonia could be forced by its ovm pressure into the apparatus. For measuring the pressures, the mercury manometer offers itself as the best device. It would be extrem.ely difficult to find pressure guages made of a material not readily attacked by amm.onia, and even if such a device were available, it v;ould need frequent calibration. The mercury manometer is simple in oper- ation and gives the absolute values directly. The apparatus must be made of some substance not readily attacked by either ammonia or mtercury. The two materials which suggested themselves were glass and iron. A test was made in which pieces of glass and iron were boiled for the same length of time in ammtonia solution. It was found that the glass spec- imen lost much more in weight than did the iron specimen. For this reason the apparatus was made of iron. Iron has the add- itional advantage, also, of possessing a much higher tensile strength so that the higher pressures could be used with safety in the apparatus « With the foregoing considerations in mind, the apparatus described in the following pages was designed and constructed. r I U ■■ ■ ■ ■■■ v*. . : . : -i ■ ' - v: ;' ’ vra'ilJi'' fc-' ...T it q 20 J^pClU^/Sr 'i‘f rt,7f^ Ht' ‘ ■ ' -V - ^ ’'^^'31 ‘ ^ ^‘. - '■ ' .. . ' *’: . • •»£'..' ■iV'- ' 'I*', «-*T\ .. ,iv -.- 4 : rv'^ii NfcT { ‘ / '-■f^ ' ' .- , ^'' ', (^’< 3**50 i: *K< ..J nidi ^ ,‘v ;-V.:,.' • S-. • ■“ !i. 1 pi fLirot'' r-. V, hTjiioAV* :Ji' ' 5 s»tf?‘'nX< e«^ oTnT ( ' ■ ' > M-'* ^‘’ " ‘ : I ffX. -y*it:-':< r. , '• : • . • • Vi'- ,(roK*'iX > v;f •..., r 4- w fi>i IXOW: • m-.' • oTn-r rtt»Xv;»»j!> ii.nlita «:i«4:. ,. ,:; ?- ■■' ^ ■• ,• ■'-‘’,■^^''' 14 ,^ ■" . . , ■' i.*« ■ c^rt' dH- \ , 'fJ: .'Oc/0;Wia W' A ’■^-1 * K' < f* * (Tx oBwa ,it^; ^ : ' fi^s-3 *t<'^''.6-’5iXi:tQV.(^!6 ‘‘'^1 >/'! . " W'Xoi:‘l £>- rio'ii / *'ii> 'Wr ififk;lm 'fri- '•/♦<> i%^ -v_. ..xj::' '^ ' .-y ^ .. :-r--f;i^.' ? - s iL'f ' Tr(i;>*u . . fxt^, ' f *uiH, \^piM ^ - ■W- : ,. ., . .. -‘^ '^^‘.''^^'t^'' ^.. ^ ry| ^,k<.i;io(s%<^O.Z. aild . Ji “ 8 %a jWiwaX?! '^S''r!i,/fi 6 ^ . iir k’ ■ 4 ' : ■ ^^ ;■•*/•.■’';■ i ' • • -iSfekaS' 'Y,;- ••"= ‘'■tfr^'InfMi' i'llB ' v;.. ■ ilk: 'm; ,5 { C;^»>x: 3 g 3 ;gaR:: 3 =ss 3 j^ .iyJy V" « ■'Vl, ■ 7 , 8 . IV . The Apparatus . The ammonia solution is contained in the vessels A and A,, made of 2 inch black wrought-iron pipe. The upper container A is 22 inches long and has a capacity of 942 cc. The lov/er container A, is 16 inches long with a capacity of 650 cc. In order to facilitate the attainment of equilibrium within the system, A. is provided v;ith a baffle-plate arrangement made by twisting an iron rod of small diameter into a loose, irregular bundle. The t?/o pipes are closed by caps at each end, the two adjoining ends being connected through the 1 inch valve X. Into the cap at the bottom of A, is screwed an l/8 inch pipe which extends over to the mercury reservoir and manometer. In assem.b- ling the apparatus it was found necessary to put a thin mixture of glycerine -litharge cement on the pipe threads at all of the joints for only in this manner could a vacuum-tight joint be obtained. Since it is necessary to have som^e method of keeping the meniscus of the merciiry column v/ithin the apparatus at a con- stant level, some device had to be installed for this purpose. A glass tube v/as inserted at B so that the meniscus could be easily seen and kept at a certain mark. A great deal of dif- ficulty was experienced in finding a suitable means of sealing the glass tube to the iron pipe so that the joint v/ould be im- pervious to ammonia and mercury, and at the same time, be vac- uum-tight. The method v/hich was finally successful was this: The l/s inch pipe on either side of the glass tube was )»> v.^^<|« ,s. '.fa, t ■; . !'■■ . f- I? V. ^ ?JtT* ^ -"4i4‘ ^*'«i«,n:os) «f .« '''''6 v • ^ •„ ...; ►.'■ . . .-‘4 '*'■ ^'•- . .• f 5 '■* -*■ teiffieJffoo he0iT ;l: ^ tvirr'® a .00 '>' i'" r.^iflOT'y ■-* ' ti / 1.^-;’ - w<''rj -;-.i‘*i-rt4>0'/,1f ‘ ■■d,f ilia Jiff. *‘i*:.n^;* . ‘' : r%Jf0a !f T •TJ, m'ttt-* . I* ^:iw$ r.-vvAorp' ^ .'kid '. < (j ‘■V ■, ■• ’.•' -■'. ■’,'i- ii -'■ ■ '■ . ■■-• - ..03^ .' 9VX«v flOjii i e4a. Vr' OsJfeonflej vti^ ®.'i/»(^. awX^OtW' tV- ■ • f- ;.i. , , FV'V -\*'^ '^' '■ ■'* iivMar \i »/''■’. ’aI “io VV fT^-38?o«CA '•' y' Mild ^Ifrv^^M v'niyf>'i»ttt *xe’¥^ ?f ^,.y '^'Pa o^y •3^1'?^ = . '* ,-•' 'f/' ' . •■ - ' : :^' . V ’. i “ ■ ‘ . K' ' ■ .,.'■ _ ' , . . •. '-Jk'' " . .._ ' Vji /r.. - .’ ‘ : X mi^ y m . piU *l pi® * r^o ^ • ' >1* ■ '. ' ' '■ ^’ . ‘ V''.. ,1S '■ ■''•ifei ^ a<^ jri^af 4iir-r'j~^uo-n- ‘wrr.iivt oj !*i" V” '•■■, -■' .'' ^ ^Isiy ctl YZ'iv 'na'^ i' r ■ >> . ’y? I . ' b4^ etrpe 'ovjsiji/py \.4o3«oof>r( *r * ' ''-'%. * ' ' p -*TOP a y« 5 j 1;# m/'X,Po B .■."'“ *■ . -■ ■-' . ''' ■' * '■f' . : ,, .'' »^ ' f • b '6^ i>tiiot> &x! ^9 utat^ • o.^ .xT d^.<# 5^tTC't?feA.'p’.-vw iJ'fe ^ - ■'- V* . .1. .. ■•■■' ''v.v " Ijj; -■ U'' . 10 rj>^f3, ft4:«.M(5>Q J» .ta f”Xleuo ■f j ti , *. ^ ■• . ■■ >v» - :p.m :V ii:*M-- ■ . J~ \ ' , ■ . ' 'r- '•')•■; / •. .'r- I , '•"*,••13 ' ■ ' ‘.- . ■».’ ■'' ' m /..I iUitof: ''4v 7 .■‘yi<^ Off .■ -v / ■'--/. ...v^ ■■ , ’-■ ■■ 'VT ; ■; ■ •< T'< ’i 1 ■> n t)7;a' ^ hadtilim ' 6. >5/ .''•^‘»5, iVJ . ; .„,v.... i, i '-r '-ii f • . : ,'r^J 9 fitted v/ith a 3/8 inch bushing on which v/as screv/ed a s/s inch coupling. The ^lass tune was then selected of such a size that it fitted easily into the couplings. The space betv;een the glass tube and the couplings was filled with glycerine-litharge cement. After the cement had hardened, it v;as covered with a layer of deKhot insky cement. This last covering of the deKho- tinsky cement vi/as found to be necessary as the glycerine-lith- arge cement is slightly porous and allov;ed air to diffuse slowly into the vessels A and A. vfnen the apparatus was evacuated. The layer of deKhotinsky cement remedied this trouble entirely. C is a black-iron union inserted for the purpose of simp- lifying the assembling of the apparatus. It is located about 80 cm. belovj the meniscus line at B so that at all times there is pressure within the union. This was found necessary as the union leaked slightly under hieh vacuum. Under pressure, how- ever, the union did not leak, the mercury inside evidently providing a sufficient seal. D is a reservoir for the mercury made of 2 inch iron pipe. A guage-tube at the side registers the level of the mercury within the tube. At the top of the tube a needle-valve Y is placed. On top of Y is a two-way stopcock. One side of the stopcock is connected to the compressed-air line and the other to the vacuum line in the laboratory. Then, by turning the glass stopcock, either pressure or vacuum ii put upon the valve Y. Since Y is a needle-valve, this pressure or vacuum can be very gradually applied to the mercury 'within the tube, thus allowing a very accurate adjustment of the meniscus level, A ■ -') . 1 li' ■ i.il vilwM ^ ■ ; 'i - ■ ■ V ^;• J,. tjfJw fl 1 ■ ...C'r/^OG rvi;^ jfjTh . ■ ' '■'' , K Lo vw ■• -. J J nsfM .V' v 7 « - . * ' f A C \ ' ■ ■ ' . ' f-i f .-faewn -i* .. p 1 ' '■.' .:" 6 - O:'.' ’■ ■ -‘■/f'l 1 Uti ) . U • .'»\^/ r .•. ? 1 ;! : •..’r-ifl " Tr;.-; -"■■■'j ■: AC' -.' . / ■ >■' ■’ ^ ' 4 c . '• t . . ; 0 . . ; • .; ' ' ’ »■' ,'' 0 .+;' : ' ,'- 1 tl . V’ ’ r ' - • ' ' -:-j: ' ■ » '■ , 1 . . '■ J fi " ■ - 4 ili » ■*'" i. .*/ 1 - ' ■ ■' ' " ’ 1 . . ^ < • ' ; ^ rXd.^lHt i£_ — ^ ^ z ■ ■ r -'v *2 ^ ■ ■■ •' ' ')», y. V ,’■' 5 • •■IrU . . P»o Jl< M'i Oi’> it ’rt i ■ •''.•! : •S , r * #• -r ? • . tj ■f ',.<'• i ‘V K,.V / ,i C ' ■ y \ ■ ,'■ r t'l ^ 'J 7 .t i -'.vXa'- ; -J e/f*^ 'c r ; . • ■ ,c . ■ - ' v.: . . . -r>ot:C - 4 ■ , ' ^ Ul \ "IC 0 .f '1 . . 7 Ga 4 :£|; ■ : >f i I" . :' ,. .-J . ■0:-!^.: ,i -i ^»P . .JJ .r cj ' i'iD'.ti’ tf’t «!A ■■; '.V. .•', 'r: ■ 'i 1 e , .'SCnffOitt , I .4 I ■ ' ■ — - • ■■ t -5:* ’■'■'J'-ri- •: ■" ■ ■• ' .' ' tf':';;? ^ v* . . • • 4 '7 • \ i V/-TT -A. 10 plug in the tee at the bottom of the guage-tube affords a means of filling the tube with mercury and a similar plug at the bottom permits the tube to be emptied. The manometer E is simply a straight glass tube inserted into a coupling and sealed as in the case of the glass tube at B, In this case, hov/ever, the tube is sealed in with deEho- tinsky cement alone as the ammonia does not come in contact with this part of the apparatus. There is the added advantage, too, that the manometer tube can be removed at any time by simply heating the joint. This is helpful v/hen the open man- ometer is replaced by a closed manometer for use at higher press- ures. The height of the meniscus may be read from the scale shown or by means of a cathe tome ter. Into the vessel A, a -g- inch pipe is soldered v/hich termin- ates in the valve F on the outside of the thermostat tank. This valve is for the purpose of withdrawing the sample of the liquid phase from A, as will be explained later. At the top of A, pipe connections are so arranged that by means of the valve W amiionia gs s from the tank I may be introduced. The valve V has several functions. It allov/s the vessels A and A. to be evacuated by connecting the vacuum line with the system through the connection at F. By connecting through the collect- ing vessels H a sample of the vapor may be brought off for an- alysis. By connecting with G water may be introduced for the purpose of making the ammonia solutions. For m.aking these connections, Y is connected to the part of a union containing the female thread. Then parts of exactly similar unions containing the male thread are attached to G,H, *■* . . . ^ 'j. ^ . * •”.; ... ill/ ' '■' ■ . „ ' V 5»<‘<'' * 2*./li5f rQ r.O • -- - _ ^ . ;>< ... -•' ■ •v.T!' - ai.t ^(t'.V e*: ;•^.^•^;?■a'>1^ o'rfirii -, . ., L/' -‘ ‘ J 4'^' ^v^’’- ^ xt - ;. -^- .4^^<.'l'r r ,%9Y^xt,n k ^ 1^' -i r *.*a; .■•♦; ii&‘ fmf ^A9Ui} iiirTr-:ar‘» e .« _ , . , 1-.: Bff' ' -•?MAi>i'i^ tJri 1© f->a • nfi.-o -lin-i fiftiiic/ ffiifi .’-litt ®i, 1<> «/i«4*?:i vd tM . '* - ' , tj^»l*iC,‘. ti ^<3 ' , ‘ , • f, ’-CAT* •'•• ••■•■ " V '•■•:’* v! ■>>^>.:.f cuf'^i ?.cf iBii;* Ic ~ A V*.^ * B It '■ ^nMm4^" u« t » f t.rtisfcic^-irx li-’ ■■ ' ' ik'-^*.t ' .• ■'• .< •■'XiPwiiv^. .1^ i ' dvX4V r;! «iVi-M ,. ** ^ ,i ■ V.. ■ 'tq ^t|r T (t’i «ivX^^iT...1^f.^', d/ X)"’OlnC(lf.y'. rd Jtxir T,;*. , ^.-iUO^ri ©31H T^t^n^v lii'Woi Mm V^vX^v e "* '^ ' •' '" V''. ^ '^‘ ■ , ’’' r /' ^ s' ' .^Wil IM •’. ,wi.t d jipjt f>d; A' ■v -i»« kpt iiSS^fitr^a f5d' ‘'''i^ir .\r.ff>tt.. '.^^H ■* ■••^.' .• •■ • ■' . -|“* • -^'> '''^.y • .a’l- ’/ *id¥\-3*' '* --' ahl-v If .ftjjVi, »;»; . . -flCiSitT !IDi^'«*Jo'; -'■ ^i:r i.. - ..''-i’^W'M „■■ s' 1\ sse&li’ “'',:i®iiSi . ' -■'>- ^i^bH /U : TX>bh*:^‘ jI'** T «IAI . .*- 11 . etc., so that connection may be made with any one by screwing the union together. G is a glass funnel sealed into the union with deKhot insky cement. H consists of two collecting flasks, H. containing standard dilute sulfuric acid and H. . containing concentrated sulfuric acid. The latter vessel is connected through a glass stopcock to the vacuum line J. The vacuum line J is made of l/8 inch pipe v^ith glass stop- cocks sealed in as shown in the diagram. The stopcocks are sealed in with deKhotinsky cement in a manner similar to that of sealing in the manometer tube. The upper stopcock is for the purpose of shutting the vacuijim piimp P from the line. The next stopcock allov/s the vacuum to be applied to the sampling vess- els, The third stopcock, v^hen connected to F by means of press- ure tubing, allows the tv/o vessels A and A. to be evacuated. At the bottom of J another stopcock is placed to be used in drav/ing off the samples of the liquid phase, Imm.ediately above this another stopcock is placed so that the vacuum, within the line may be released at any time. The manometer J registers the degree of vacuum v/ithin the line. The vessels A and A. are surrounded by the thermostat tanks T and T.. The thermostat tanks are made of sheet iron surrounded by a thick layer of wool to insulate the tanks from the surrounding atmosphere. The stirrers operated from the line shaft by the motor M, are of sufficient size to give ad- equate stirring. The temperature is regulated by the U-shaped mercury regij.lators shov/n. These operate in the usual v/a:/-, the low-voltage current being furnished by the dry cells L, The r,esistance N regulates the current which flov;s through the JJ f •it. tl I'.'' 4 -*j. .'I ? t’ t. a Z 0 1 ^' ^ * -r'J- V ; u ' 9 '. *« 'IT J 12 . relay R, On the other side of the relay, the 110 volt current is connected through the relay to the heating lamps at K. In addition to this regulation, there are coils (not shovm in the diagram) within the tank through v/hich cold water m.ay be circulated. The liquid in the t'mks is vmter for the m.easure ments at 0 C . and oil for the other temperatures. The valves V, V7, F., , and Y are made especially for use with ammonia solutions. They are built by York and Company, and are of the so-called expansion type. The needle seats both v^hen the valve is open and when it is closed. This el- iminates the leaking around the valve stem v/hich Vi/ould other- wise occur, and permits a high degree of vacuum, or a high pressure, to be maintained indefinitely. Since the valves are of the needle type, they permit a very gradual release of the pressure. The valve X is of the globs type and also seats either open or closed. ^ -^- ;*irft4wm (I'lOv. Q/l .^'^f»rVx| ifl ‘ : ,, flB ■*- • .-,. I'S ,.. s*. •■ • e>»'''‘.I Wjii WJ ^aJstonao rnwrte ioia, afj.-3 -x.. fi-niy ./roid^n^B., ltd?- ns.•a^lt«»^<.(» !»?..';» ■<*<«« (dSjaiit*«4#;.^ ;; -ftaij-u,* ,114 -((rt'Tfcii* .t «aitidi |' ‘•fi®- «o» fjfc.6it4 •■>,». 0 W «dn& l.L V . . . ' • » I V 'Tcl omr tna y ijr^',.;' ar(7''^ : — ^ ®y ...\t’ineiJLUi Hix- :/rcoY SSJjsr a^k itxW. ^tt{^M '4^ «c-aL'Aq4^^joski|iu>-os lo'*i^6nii - ud «1 . -t:;f'Xo ei .71 n#^p ei ’SVlin?' > stir Oi rS^tTfr^C*^/ Ot 0H- r> g«» W/.-ft- v4 -5c cl^X I^xcv virty ,frw¥U^' ' ' '•f'' V ' . K. .r»e‘«,oXo *to • . »H^irt A »Vi-\ Mki.r.BkKX %». ... •'- ' . . Li,;. .■ •• ': j ■ ,; ■'4 !4 ;lo Bsaslr.-. ».■ iix-ia'i %W eiWioiT sad^^Vi''^ '’ . * .. 13. V . Calibration. In using the apparatus, the first thinp to be carried out is the calibration of the manometer. A m.ark 0 is drav/n upon the scale at B as the fixed position of the meniscus. Then, with the vessels A and A. open to the atmosphere, the level 0 should be marked upon the manometer scale. Then, in taking readings, the position of the manometer meniscus above or belov/ that mark will be a m.easure of pressure above or belov; atmos- pheric v/hich exists within the apparatus. The pressure which is v;anted is that at the surface of the livmid phase. Therefor the pressure read upon the manometer must be corrected for the pressure due to the liquid within A, where Pv Pi the vapor pressiire of the solution. the total pressure as read upon the manometer. the pressure due to the column of liquid. P-t can be read directly from the manometer; P^ is the quantity to be determined experimentally; P]_ must be calculated. The pressure at the bottom of the column of ammonia sol- ution is equal to the v;eight of the solution divided by the cross-section area of the tube. The area of the cross-section of the 2 inch pipe of the vessel A. may be found by adding a known volume of water to the vessel and measuring the heiftht i \ , 8jL 0 r ffiofn J..I Hffcw? f.-.rT ,.i:j ;»o ->5 - : fi,or.|^^ y~i t‘' ' :^Uf . »-v ■ piTw S 'o ,;c>r • • ;Jt Il’Iw atK* ';- Ic' 1- 'j ' c '- ' ! rl '■.•■J '!c : > .,. T„ i C r: .1 . MVi.JOO OJ •■'£iVh;i.»' - /i t;|) ;t[ ‘-'Ml . . •.■'■• I 'is^ .' ..^ j,. rasjuA’co I i-fl>ivi -i It ;..;•« / Vr v. 1.1 1 : J ,■■ ' ' ‘ •• : - '. j r . T • ( ■ ■' ,}■ o r. jnr £« ni- ' S.''.',: V.u ■ -■ ■•'! ■O'll '. ; • . i i. *i Jf Cli 1 r. i 'i c- q 7 n 1' c. .-?ro ,.’ . .M ryjj^Bo'iq : .: i 'r:;j oi, lairp® ■ ^ ■■ { 'lc'^ t .J iV n:* 'io ■ •» - »tf r;; j -CJ^O-IO * ^ r T •; r cJ 'X9^tjaw 'XQ sr'jjlor ■ o"'' r..K^r:c*4?;y!»r- - - - ). '■•.V 14 . of the resulting colurnn of liquid, (This must, of course, be done before the apparatus is assembled.) Then where V “ volume of the water added. H - height of resulting column of v/ater. A = cross-section area of the pipe. The calculation of the v;eight of the solution is simplified if it is considered as being made up of two parts: airmionia, v/hose weight is a variable quantity depending upon the concentration of the solution, and water, which has a constant weight in all determinations. This last statement is true providing the solutions are made by adding ammonia to the same weight of water in each determination, and that is the method of procedure v/hich will be followed in using the apparatus. The pressure due to the water then, is a constant correction. W H2O . p A HgO VJhen W jjgo ” weight of the v/ater added ( 500 grams ), A : cross-section area of the tube. P Q = pressure due to the water in the solution. ^ ( srams-weip-ht ) . There remains the problem of finding the pressure due to the ammonia in the solution. "iy* ■ • '■ >-^: •> '“ ' '‘...a ■ ' V.,* < ' '‘4*5*' ,‘>r'fi X *S: m ' jlij ■X- ' if ‘ =f.v # W’ •V - . ‘ I’ • * .y'. %ivj>< ; ufQ,# r-lif V- , f'* r^ -* ’ " ‘ ' ■ '• , .•■'.N'fc./r. 7 /T* • •>rfi r^r.'/'jo' j^%-: i '] p^^,\it!: /n*-£^« 4 6i.M" ,‘r-> ,im ♦ lO p*Ali.}( a*r/rn ujj •^ii^;9P'ir?‘ ^i^fas “ ',-j •'»U' ''^1 I ‘J_-.;,.|««'tiI lo fcc..i-»>Jr:.|K;# =i S<>t^. -MiW' ^ fit H^t, •■■* ^WS*«-ni etT . enlist .n>» >:i ji(, ^yi ; 0J^‘ /i* • — • — 'H'- - ,v . V -ts '• ■* A • I XiStSS' r'-.v^-s - >' -•rtw ’'•■" lb b.:>^-'*‘.- eJ 5k, T^- ’ a t # i * i '• " - " T" « y~ *h,^l\ t .. >ip 03T ©^', Sk'j.f»«8 0‘t(^ ■• o- - V.-. !■-?.,«».•. ssj.:^j| -•it,; '< ■ .< 15. trom the analysis of the liquid phase, the weieht of the ammonia in the solution may be found. Then A “ This quantity must be determined for each experiment. It will be noticed that the pressure due to the solution was calculated on the assumption that all of the solution was in A,, a tube of constant cross-section area. There is an additional pressure due to the liquid contained in the l/s inch pipe and the glass tube leading from A, to the mercury ijieniscus at B. The volume of this amount of the solution is so small that it need not be subtracted from the original 500 cc. of the water, (all of which v; as assumed to be in A.) on account of the large cross-section area of A,. In the l/s inch pipe and the glass tube, hov;ever, the cross-section area is so small that the resulting height of this small volume must be considered. This additional pressure may be found by measijiring the distance from the meniscus level at 0 to the vessel A, This height, multiplied by the density of the solution ( from. Landolt -Born- stein) for the particular concentration ¥/ill give the last correction to be made, - Px v^here H = the height from 0 to A, D = the density of the solution, Px z pressure correction for this height of solution. 5 Tn 'fr V* #V F 1 \ ■ 'i' ' ■?, V '*,' _ , . • ‘V '. 1 ^, J f :3 ^'C< vttr - •'■ C’ >■•-. ; 1 . ; / 1 j ' • 1 * -V it . */U\ 4 ' ( 1 • ' • ^ ' 1 %..; ■< - l! • ..V*)*! ■ .u'.£ t.r-.r i iJ,f . r » \ t 1" ' 'vi.«o'( tisk ' -' 'K.- • ! 1 • i ;i . •: i f4 i r . t . !, ■■ -•■!* i;^ f>qr\ > - > >- h v< . .»> n ( ■ ■ \j !; ' . *, !'• ■i ' • fi:* Mw \n fl . , • , A- * • •;~v>iOT;d .' •••' '' ’Wli’lr* 1 k r i.y. I '■ 111 ' ‘ > r4 ''*:■: • •- -•* -* ‘ ^-Tirv'^-f «r • , . 1% .. . tCt lv.uti •.. . ' ' J iSflliHi T. I :rj': 1 ^ t ^'^“.i-'?'/: dni - 11 J '. If> • c/:i 'N: X.«. . ■ -i if 16 Then Pi 13.595 where P-, - the pressure due to the total weight of the solution. ( in cm. of Hg.) t 17 VI. Oper a tion . For the 0* C. readings fill the tanks with crushed ice. For the higher temperatures fill the tanks v/ith oil. Set the thermostat regulators to give the desired temperatures. Open X, connect F to the vacuum line J and evacuate A and A.. Close V, attach G and add 500 cc. of water, closing V quickly as soon as all of the v/ater is introduced into A to prevent the introduction of much air. Open W, admitting the ammonia gas until the solution is of the desired strength. This can he told roup:hly from the reading of the manometer. Stir the mixture somewhat by lowering and raising the mercury in A,. Close X and evacuate A. Open X for a minute and evacuate A. again. This process eliminates any air which may be contained v/ithin the system. Close V and stir until equilibrium! is obtained. This can be judged from the readings of the manometer. VJhen there is no difference betv/een successive readings taken a few minutes apart, the system, is in equilibrium. V/hile the system is coming to equilibrium, H ( and a similar collecting device for the liquid phase) should be weighed. A.fter the equilibrium has been obtained, read the manom.eter E, close X and draw off a sample of the vapor phase through H. and H. . . Dravj off a samiple of the liquid phase throuc-h F. . In drav/ing off the sample be sure to get the press- ure on the outer end of the sampling train lower than that v/ithin the system, otherv/ise the sulfuric acid v/ill be drav/n ■Bi •*■ -.ftoi. rjc,vA-Tc ail 2 ; .0Vj« ..-io--^„ ..'•i,,,,. ftp Ks ■ . MJ -•>>* ei ^ :. • V « 4 ?ofr«rai» qiKid'^ >> .no t y 'oaojO \vA • 0.? '‘u: bc'.up.t’r^-.M t« rir; b;» , nopr «i> 'xSit6lvp I. V - 4 A't: 0 ' . 'IB ,i-M?» 1, noi ;94-w'*tof ‘*yf^ \.rt4wW ■ Aiwa •-< -., 1 . piwrr-i - - •* M»nr,j.B-'^!P.,vfx,irt -.f‘ *« .*.<,(x*m. • ft £**' • ''T^* w*' •* t' k 0^ V 9 ,clJ ■..■■: .,,,;, BJ.-, «!«•.... ed v., i^dlV*. lliiM- rj.fe b/j«e •-f.*,I«di')Bi «AL^«ilud» ' 'l*t. - ii ' J ■' .» i' i,i O'Xriii/ TAtfW' ®rt^ r*.rxi-s-Y»4’ A- ;o*:fiijf rt0mi&d : 'S- ■ tfl. '‘‘K ^1 ^ Mojvnb .««<1A, »W: 4 ■■ .1 ' • ♦= ' ’ w • , .-,1 -*» .;, 'it ^r:It Afrm^k, ‘i6^aa5X-9w Y/?’‘ tft fUttJn ai-,. oJ an{lil -ul ^ ,1 ^ uocSi'LOtiit^ ;-jft &noi'.j owbV f --, , • ,!• i .5 . eM;t icj ©erod'd m:: a npy-f^ s^Ipacft '►d? o K5ti (!»»»■ W4- dti BBO-sso^qinl i-jo^ .‘ia^r5ir » X-'»Itd;*cf fcifca "tftf >■ W-'*'- ., -.'f J •Jj... pt' ♦ 3 ' » :,‘fe-.l ti ■t ‘f- ‘ I '■' i- ..■» ■> "' t ■' 'fc h ■'. M-r A ' •■’ • ,tf - ' Ji ■ , :-.. « .-A - -j. . ii ■ ' a" ■*' .^i. ^rj:;^ .h* . > . I ' -xv ►- ■"* ■ ' **’ • ■• • ’ . ■' .* ’’r'‘ ' jj l\ p 1 . Vj*-.'fia^il^. > ^ A.r^< ^ t..aSnlBHll !■■', ' . *■* 4 . ^j| '■ la k. ' a ^ ii/.-.irt i li . 19 . VII, Sumnar:;- , 1. An apparatLis has been designed and constructed which will permit measurements to be made vifith a hifrh dej 2 :ree of accuracy of the total and partial vapor pressures of aqueous ammonia solutions, 2, The calibration and the mode of operation have been described in detail, o. Work is in progress on the measurement of the total and partial vapor pressures of aqueous ammonia solutions. I t . 8 rf 1 1 ^ jjf^ 0 inokrfjS T,! i ’ t f ■' *^0 « ciir.. J>i-.7r 0f -t". ■ ■' *• ■■ ^ 1. ’"i 1 ■ ip ' j '■ ** .*■'■ .- -''' /«! i: i^M \ ' V s? I ''1? ■-' <'I’“3 /tM "m- >>' ^ ’ '■ 'v^ ’*^ „_. J-V'V ■ vfTiBW ■ :.-■. ■ i "Mm ; “1 ' ^ ^ ‘ ■•• i*rfi^ ' ' I ’ ^ r ■ ’ 'i ‘ ‘ .{. < rt.-' “ S •; '■ ' . ■ •■ ’•' ■•■ ' '■• • ' .' 20 . VIII. Acknowledp;inents . The apparatus descrihed in this paper was designed and constructed by the joint efforts of llr, Thomas A. Viilson and the author . The author wishes to express his sincere gratitude to those who have helped him in his work on this problem. Dr. G. Diet- richson, under whose direction the w^ork was carried out, has maintained an untiring interest in the problem and has given many thoughtful criticisms and suggestions. Dr. Rodebush and T.E. Phipps have offered much valuable advice which greatly simplified the construction of the apparatus. r-t; •s' ^ I •1 ‘ >- - v.'S'rLT''- /Xr f% nc * . j ■ il . 0 » ^ If Ky¥ *■ '•>• * i' \ 'V ■ ■ ' ^ '^.^f- \' -1' " ft, 'i. »'.>♦' V- •■•>• * i'' • ••t’* h •■<■■ - ■ V -.Cl'S ' ’ ' ■%■.• '■■ '" '• ■ k V .s '., V ■ ' -' ”' im ':'.<*- .£■ " ' ' . ■■ i'/'"' •■TJ.sy i 5 ifr.» L ivV’"' I ‘0»S <*• ls.‘ ‘ill. .' . jX ■ '” f' r: ■ T ■'’'^•' ^ ,^ c^J. I'- : /. ■ ■.■ '•'■ ^ h . ,^, '-fe ^ V • • ^4*r.’ *i ’ vi » t ^ .; \ *’ .••' ■■' '' 5 '1 ' ... ’■i ? ' .' ' ' y yu'rW't*^ T 7 , .., i ; '* ''' ' 1^’ 'v?'' '- ... . /' .• , .' <■ " ' ''■.* >>■ >.>• ; ■* • ' •-•"?■ , '-’v ' .iv»\... -■■ ■ i: •' .-.'-miv.JIL ^ ,';V Tw». '. ' ■:'• >* ^ s t ’ '. . i . 17“ -t’ » I «' <• »;^. Its ,W. u ts. ■ ^ . r n- ■ j - T*'’ i*--' * - k' fcSiili.:':.-; '. ■ 1: %v • .*« ;v..i ' j ‘ ^ /-iX' ' 1^1 ‘ t " .ffcr ■h,‘.^' M*?! . -4* - '■ •1 -'i A ‘ . ■^4aiu V v- dy: 'p. >lv n* silv» * 5 S#!i'>i, ;:»y\ ' il > 'i"*--' -1 . ■■ *' >WJa .^.ivfe , . i, .-.- VI, .A;;- l?:raa»JL;=gagK3S:’ Xkij^ 21 . IX . Blbliop-raphy , (1.) Ann. d. , Chem. u, Pharm. 118 , 1861, (2.) Journal of the Chemical Society, 22 .* (1901), 718. (3.) Ibid. 83,(1903), 1186. (4.) Proceedings of the Royal Society, 22 * (1904) 72. (5.) Zeitschrift d. Vereines deutscher Ingenieure, 52, (1908), 1315.