on Lactin.” By M D - Royal Societyrspl.royalsocietypublishing.org/content/28/190-195/273.full.pdf · a nts in connexion with this remarkable compound, in the hope, ... formula Where

III. Researches on lactin

Hogarth.Edmund J. Mills, D. Sc, F. R. S. and James

January 1878, 273-279, published 1281879 Proc. R. Soc. Lond. 

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1879.]Researches on Lactin. 273

■ “ R e s e a r c h e s on Lactin.” By E d m c n d ■ M i l l s , D.Sc ,■ R g I y o u n g I P ro fe sso r o f 1 ech m cal C h em is try m A n ­

derson’s College, G lasg o w , and J ames H ogarth . Received December 4, 1878.

Although lactin, or sugar of m ilk, has been investigated by num e- hetnists there are m any problem s connected w ith i t w hich still

r0ttS,fC lution. W e have accordingly undertaken a series of experi- a nts in connexion w ith this rem arkable compound, in the hope, no t

l f obtaining special results, b u t such as m ay be m ade available ft studies of a more general natu re . As our w ork throughout has been for the most p art optical as well as chemical, we have first to state our methods of obtaining th e constan t of Je lle tt’s ' polarim eter, the instrument employed in our investigations.

J Determination of the Polarimeter’s Constant.— a. By quinine su l­phate; 5*5412 grms. of the sulphate were dissolved in w ater acidu­lated with hydric sulphate, and the solution m ade up to 100 cub. centims. The average of five readings gave a solution of —25°*73, equivalent to a specific ro ta to ry power of —232°*16. De Gris and Alluard* give —255°'6, a num ber w hich is to our experim ental num ­ber as 110096 to 1.

|S. By cane sugar. Three sets of experim ents on solutions contain­ing respectively 16*3500, 8*1750, and 4*0875 grm s. in 100 cub. centims., and embracing five, four, and fou r readings, gave a general mean reading 21°*74, equivalent to a specific ro ta tion 66°*48.

This is to the generally accepted num ber (73°*8) as 1 to 1*11011.<y. By salicin. Two sets of experim ents w ith solutions containing

respectively 4*9156 and 2*4578 grm s. in 100 cub. centims., and each embracing three readings, gave a general m ean reading 4°*92, equal to a specific rotation 50°*046. B o u ch ard a tf gives 55°'832, which is to the number got by Je lle tt’s in stru m en t as 1*11561 to 1.

The average of th e th ree num bers, 1*10096, 1*11011, and 1*11561, gives 1*10889 as an experim ental factor for converting our Jellett readings into ordinary readings.

The relation of the tw o scales m ay also be seen by examining the arc divided to read percentages of cane sugar w ith a solution contain­ing 16*35 grms. in 100 cub. centim s. In th e Je lle tt instrum ent, an arc of 21°*666 is divided in to hundred ths for th is p u rp o se ; and as 16*35 grms. pure cannose read 100 on th is scale, the specific rotation

* “ Compt. rend.,” lix, 201. t “ Compt. rend.,” xviii, 298.

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274 Prof. E. J. Mills and J. Hogarth. [Jan. 23

is 66°-256, which is to 73°-8 as 1 to 111386—a factor which differ from the above experim ental one by 0 4 5 per cent.

All the specific rotations given by ns are corrected by th is factor, and are comparable w ith those in general use.

In all our experiments the specific rotation is calculated by tht

form ula W here [ o ] = specific rotation, a = the reading h

degrees, V the volume of solution containing the weight and l = the length of the column in decimeters (in the above experiments 2).

II . Determination of the Permanent Specific Potation of Thelactin was purified by filtration through animal charcoal, and two oi three crystallizations, afte r which i t left no sensible residue on ignitiot in air. h ive sets of readings were made :—

(1.) Average of 5 readings. Specific rotation 52 *84(2-) „ 99 99 99 99 53 *23(3 .) „ M 99 99 99 53 *37(4 .) „ 3 * 99 99 53*04(5*) )> 99 99 99 99 53 -07

The general m ean of these num bers is 53°'12, which, m ultiplied by ' the factor 1*11386, gives 59°'17 as the perm anent specific rotation of lactin. The num ber given by Berthelot* is 59°*3. In every experi­m ent, care was taken th a t the ro tatory power of the solution had i become constant. Three different samples of lactin were employed. Experim ents (1), (2), and (3), were on sample I, (4) on sample II, and (5) on sample I I I . As the samples were prepared a t different times, and by a m ethod varying slightly each time, the very small differences in the results show th a t the lactin contained little or no im purity.

I I I . Examination of the Law for the Change of Potation in a freshly I prepared Solution of Lactin.— If the ro tatory power of an aqueous j solution of lactin be examined a t short intervals of time, i t soon I becomes apparent th a t a change is tak ing place, the angle through which the plane of polarization is ro tated becoming gradually less. The object of the following experiments is to quantify the phenomenon j in question.

Five grms. of lactin were dissolved as rapidly as possible (time c taken, 1 hour 15 m inutes) in cold water, and the solution made up to 100 cub. centims. The polarim eter tube (2 decims. long) was filled with the liquid, and a first observation taken 15 minutes after com­plete solution, or 1^ hour after first contact. Succeeding readings

* “ Ann. Ch. Phys.,” [3], liv, 82; lx, 98.

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Researches on Lactin.1879.] 275

m re made a t in terva ls of 2 hours, th e re su lts being given under table I, No. 21.

See T able I .

- J In order to increase th e to tal change and lessen proportionally the lat error of experim ent, i t becam e necessary to use a s tronger solution, to ^increase the leng th of colum n, and to reduce th e in terval elapsing ''b e tw een first con tact and first observation as fa r as possible. To i t attain these conditions th e follow ing m ethod was ad o p ted :— A bout -*'10 grms. of powdered lac tin w ere rubbed in a m o rta r w ith about * 60 cub. centim s. of w ater for half an hour, th e solution filtered, and a the first observation tak en one h o u r a f te r first contact. The m etal jijtabe belongingto th e polariscope was also discarded, and a glass one . constructed from a piece o f tub ing 17 millims. wide, by sealing on a side

piece for the in troduction of a therm om eter, and g rind ing th e ends carefully un til i t m easured 242 m illim s., th e g reatest len g th ad m itted by the polarim eter. Two glass disks w ere cem ented on the ex­tremities, and the tube covered from end to end by a helix of th in tin tubing, th ro u g h w hich a cu rren t of w ater m ig h t be passed to keep the tem perature c o n s ta n t; to g u ard fu r th e r from variations in tem peratu re the tube was covered w ith cotton w adding. W ith these precautions three experim ents were m ade (Table I, Nos. 1, 2 , 3 ) , the resu lt being that the to tal change was nearly doubled. In all the o ther experi­ments the m ethod was sligh tly varied, th e lac tin being placed in a bottle w ith a g round glass stopper, 60 cub. centim s. w ater placed on it, and the whole shaken vigorously a t in tervals for h a lf an hour, filtered, and the first observation tak en as before. E ach experi­ment extended over six hours, and included ten observations. F o r each observation three o r fou r readings were m ade, and th e average taken. In Nos. 4, 5, 6, 7, 8, 9, 13, 14, 15, 16, 17, 18, 19, 20, of the accompanying table, vary ing w eights o f sodic and potassic chloride were introduced. In every experim ent th e therm om eter was read a t the same tim e w ith th e ro ta tio n ; and. the average tem perature, as well as its extrem e variation, is given in th e table. T hat th e different experiments m ig h t be compared, we have expressed them by the equation—

y = a + h x + c a 58,

in which y is the angle of ro tation , x th e tim e in half-hours, counting from the first contact of th e lactin w ith water, and a, b, and c, are constants. The values of a, 6, and c, were calculated by the m ethod of least squares.

In Table I I are given the equations, accompanied by the probable error of a single com parison of th e calculated and experim ental values °f y. The sum of the ± actual erro rs is in nearly all cases zero.

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276 Prof. E. J. Mills and J. Hogarth. [Jan. 2

Number.

Table I I .Equation. Probable error.

1 ____ y —13 -9002 — •48543a; + -014330a;2 . . . . *031512 . . . . y - 14 1 3 2 5 - •56919*+ -017755a;2 ____ *0423 i3 . . . . y — 13 "6284— •49476a;+ -014629a;2 . . . . -0323 14 ___ y - 15 '4 1 0 0 - •62775a;+ -021712a;2 . . . . •0316 15 . . . . ^= 14* 6 1 8 8 - *49366*+ -013833*2 . . . . *0173 |6 ___ y = 15 '0 6 9 2 - •71727*+ -026959*2 . . . . -0519 17 ------ y= 15 -1 5 3 7 - •60585*+ -019943*2 . . . . -0269 18 . . . . y - 15 -1 6 5 4 - •54298*+ -016387*2 . . . . -0232 19 . . . . y - 15 -8 7 9 2 - •58006*+ -017402*2 . . . . -0263 j

10 ____ y —14 -5 4 3 0 - •56770*+ -018459*2 . . . . *0229 ]11 . . . t y = 14 "6154—•56240*+ -018388*2 . . . . *036812 . . . . y = 1 5 -3 7 4 7 - •66860*+ -023514*2 . . . . *0380 ;13 . . . . y - 18 -2 1 4 2 -•65254*+ -020109*2 . . . . -0224 514 . . . . y - 16 -6 2 6 2 - •65155*+ -020546*2 . . . . 0313 115 . . . . y = l 7 -2 2 3 0 - •64521*+ -020448*2 ____ -022716 . . . . y = U -6 3 3 9 - •48232*+ -013474*2 . . . . -017717 . . . . y - 15 -5 9 5 4 - •56252*+ -017796*2 . . . . -040118 . . . . y - 16 -4 5 4 6 - •65417*+ -022141*2 ___ -045519 ____ y - V J -5 9 2 3 - •58714*+ -016131*2 . . . . -008820 ___ y — 14s-9 0 1 1 - •45421*+ -012057a;2 . . . . *0255

By the aid of these equations we can now calculate the initialspecific rotation of lactin, or the rotation when * = 0 calculated to unit of weight. W hen * = 0 , y —a \ and the perm anent rotation being known,

the initial specific ro tation = -------^ —_— . The following areperm anent rotation

the values found, the chloride experiments being averaged by them­selves.

Average of Nos. 1, 2, 3, 10, 11, 1 2 . . . . . . . . 93 -98„ „ Nos. 4, 5, 6 . . ............................. 9 1 '90

„ Nos. 7, 8, 9 ................................. 91-97„ „ Nos. 13, 14, 15 . . ........................ 91-87„ „ Nos. 16, 17, 1 8 ............................. 91-37

Single experiment, No. 1 9 ......... ............... 95 "30„ „ No. 20 ............................. 92 16

Average of the tw enty experiments, 92°"63.

On differentiating the equations, p u tting 0, and calculating the(X X

values of * and y, we find th a t the values of y thus got do not corre­spond to the perm anent rotation, bu t are always greater; showing th a t the change in rotatory power does not progress according to the

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Researches on Lactin. 277

■me law throughout, b u t th a t, a t the po in t referred to, a new reaction tgins. T his value of y is p roportional to the am ount of lactin in lution, indicated by the perm anent ro ta tio n ; and th e specific rota- on calculated from i t in th e different experim ents is practically »nstant, its average value (from tw en ty experim ents) being 640,8.

179.]

I l lm

he following are th e values of x and y w hen ^y—o dx *

I d I 1 T able I I I .

l$] No. X. y- Specific rotai

$1 1 ............ 16 -937 ............ 9 -789 ........... 66-71M 2 . . . . . . 16 -029 ............ 9 -571 ............ 66 -14ml 3 ........... 16 910 ............ 9 -445 ............ 64-95ml 4 ............ 14 *456 ............ 10 *872 ........... 63-42n I 5 . . . . . . 17 *843 ............ 10 -214 ............ 65-11i l l 6 ............ 13-308 ........... 10 -298 ............ 63-31!? 1 7 . . . . . . 15 -189 ........... 10 -652 ............ 63-91

8 ............ 16 -567 ............ 10 ............ 65-631 | 9 . .......... 16 -666 ............ 11 -045 ............ 63-223 | 10 . . . . . . 15 -388 ............ 10 -178 ............ 64-20] 1 11 ___ __ 15 -292 ............ 10 *315 ............ 66-39

12 ............ 14 -217 ............ 10 *622 ............ 63-53

m 13 ............ 16 -225 ........... 12 *920 ........... 64-8814 ............ 15 -855 ............ 11 -461 ........... 63-57

in15 ............ 15 -776 ............ 12 133 ............ 64-78h16 ............ 17 -898 ........... 10 -319 ........... 65-41

'ii; 17 ........... 15 -804 ............ 11 149 ___ _ 65-0618 ............ 14 -772 ............ 11 -622 ........... 63-79mm19 . . . . . . 18 -199 ............ 12 -250 ............ 66-3620 ............ , 18 -836 ............ 10 -624 ............ 65-71

This break in the change seems to pofht to th e dual na tu re of lactin mentioned by Fudakow ski,* whose experim ents show th a t lactin, like cannose, gives tw o glucoses—-lacto glucose and galactose.

An increase of tem perature evidently hastens th e ch an g e ; b u t the exact relation of tem perature to th e ra te of change has no t been dis­covered.

The presence of sodic or potassic chloride increases the am ount of lactin in solution, b u t has no apparen t effect on the ra te of change.

IV . Action of Hydric Nitrate on Lactin.—W e m ade an a ttem pt to trace this action, b u t did no t succeed in overcoming experim ental difficulties. The first of these was the im possibility of com pleting the action w ith the quan tity of acid required for the first change. I f a

* “ Deut. Chem. Ges. Ber.,” ix, 42—44.

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278 Researches on Lactin.

larger quantity of acid were used, the first changes were so rapid as evade m easurem ent; moreover, the oxalic acid formed, by crystallizi- in the acid liquid, made accurate observation impossible. By addii the acid in small successive portions, we nevertheless succeeded obtaining an outline of the reaction, of which the curve drawn belc is an accurate general expression.

[Jan. 2

Hydric Nitrate.

Dubrunfaut, who has also examined this action,* asserts th a t tl rotatory power first rises to -j-o of the original amount, then fal gradually to zero, again rises to ^ of the original rotation, and one more falls to zero: the highest rotation corresponding to galactosi the first point of inactivity to mucic ac id ; the second rise probably i dextro-tartaric a c id ; and the second fall to the formation of oxali acid. Our experiments show the formation of a laevo-rotatory sub stance, perhaps laevo-tartaric acid. The general form of the curv constitutes i t an interesting and novel addition to chemical curves.

V. Note on Solubility.— The mutual relations of water and lactin ii solution undergo a change upon which the change of rotation mos probably depends. W ater shaken with a large quantity of very finel; powdered lactin a t a temperature of 17° C., takes up a quantity o lactin corresponding to a solubility of 1 p art lactin in 10 64 part water. W ith four hours’ contact, the solubility increases to 1 par lactin in 7'49 parts water. The permanent solubility got by thi analysis of the mother-liquor of lactin crystallized over oil of vitriol ii 1 part lactin in 3‘23 parts water. In the solution of the lactin a fal of tem perature of 0o,45 C. was observed. Pohlf also found a de pression of temperature (0°'88 C .) ; while Dubrunfaut alleges thai heat is evolved.

Conclusions.

I. The initial specific rotation of lactin is 92°'63.II . The permanent specific rotation of lactin is 59°T7.

t “ Joum. Pr. Chem.,” lxxxii, 154.* “ Compt. rend.,” xlii, 228.

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M§79.] Mr. J. B. Hannay. On Microrheometer. 279

III. The change of rotation of a solution of lactin can be expressed '"%i a mathematical equation.

IV. W hen the specific rotation 64°*8 is reached, the law of change ust be expressed by a different equation.V. The initial solubility of lactin is 1 part lactin in 10*64 parts ater.VI. The permanent solubility is 1 part lactin in 3*23 parts water.

V. “ On the Microrheometer.” B y J . B . H annay , F.R.S.E., F.C.S., lately Assistant Lecturer on Chemistry in the Owens College, Manchester. Communicated by H. E. R oscoe, LL.D., F.R.S., Professor of Chemistry in the Owens Col­lege, Manchester. Received December 11, 1878.

(A bstract.)

In this paper the author reviews the work done by chemists and He physicists in determining the relation between the chemical composi- a I lion of a liquid and its rate of flow through a capillary tube. Poiseui lie * «oa iscertained, in a very accurate manner, all the physical laws relating kto co the rate of flow, as regulated by temperature, pressure, and dimen- iNri sions of the tu b e ; bu t on examining saline solutions he could make oni nothing of *the numbers presented, because he used percentage solutions Tilt instead of solutions proportional to the equivalent of the body dissolved, c® Graham, f noticing th a t Poiseuille had discovered a hydrate of alcohol

by running various mixtures of alcohol and w ater through the tube, •tin! examined mixtures of the various acids with water, and found tha t the ml hydration proceeded by distinct steps of multiple proportions. Several Sml others, notably Guerout, J have since worked on the same subject, but jtrj as they have only worked on organic liquids, and have done all the pail rates at the same temperature, the results throw no light on the phe- pjt nomena. Thus water runs about five times as quickly a t 100° as a t

. tii 0 ° ; and in a series of alcohols, such as Guerout experimented upon, jj the differences between their boiling points were very great, so that, ji their vapour tensions or molecular mobilities being quite incomparable , jt while at the same temperature, the experiments do not admit of any jj| real interpretation. The author reserves the organic part of the in­

vestigation, which requires the determination of vapour tensions, till a future paper, and in the present deals with saline solutions.

The phenomenon of the flow of liquids through capillary tubes has

* “ Ann. de Chim. et de Physique,” [3], t. yii, 50.t “ Phil. Trans.,” 1861, p. 373.J “ Comptes rendus,” lxxix, p. 1201; lxxxi, p. 1025.

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Table I.—Results of Experiments on Lactin.

Nature of Solution .... | Aqueous,Containing 1 gramme Sod. Chlor. in

00 CO.Containing 1 gramme Pot. Chi or. in

60'ef. " 'Aqueous. Containing 5 gram m es Pot. Chlor. in

60 *'Containing 5 gram m es Sod. Chlor. in 10 grammes

Pot. Chlor.1 a f c S ? - -

jA w m Temperature „ . J 10% [ 10*8 11*0 12*2 i<?i [ 1*8 12*2 -10*5 [. - 1?°1 ’f , i # i K ® 1!j§- ii°*4 13>1 11% 10%#&& lll7rt*>; l ^ 9 r ^ 11°*9 1 115 l

• m t I 12*017 I 12*976 12*750 14*288 13*087 ' 13-833 . 14*070 14*147 ! 14*823 13*524 13*523 ;; i4**i:9X) * | 17*033 y-\|^*460 [** l#*0l'2 13*730 14*633 15*317 . 16*483 J 14*0839 i 12607 | 12*687 12*270 18*788 13*292 13*167 13*487 13?7I2 * 14*292 ' I3,*01C0> , ;p*%3#f.7** 13*600 16*435 ■ 15*847 15*503 ■ * 13*350 - 14*035. 14*717 15*98,7 : j | 13*6504 / ISrtVJ 1 12*067 11*888 12*187 12*847 12*583 13*050 13*262 13*833 | 12*542 * . *2*640 ^f-.i3-040 H | § [ J | ' t 1 14*312 14*954 ^ ‘#2r877 13 590 - , 14*C8f ^ 15*480 13*26,3;. 11

/ § | 11*800 1 11*860 11*467 1 12*840 12*430 12'078 12*567 12*831 18*367 12*100 ^ i% 2 4 0 , 12*547 S p i$ 4 3 8 f i s - m r 14*505 13*193 ^ i ^ 9 © r - - 15*053 *1 1 12*853 1• I 11-480 / 11*880 11*119 •1 12*802 lilk b . 1J-707 12*230 1 12*485. 13*000 ' 11*790 i 11*873 12*147 if* 1‘5J* ^ » C 13*380 I4V037 ; K |i*793 13*293 u m o 'M7 11*187 / 11*100 / 10*888 I 12*060 U ‘817 | 11*330 11*935 12*143 11*490 11*843 14*633 V h 13*073 y^-$§747 11*930 12*525^ \ 12*986 i 14*290. $8

•

10-9881 1

10-680

i 10*016 i 11*817 11*680 i 11*070 11*540 11*850. ! 12*377 11*193 11*340 11*567 14*270 :- l 12*737 13*333 1 ■ 11*66.7 ij ' ®2**f53 ! 12*650 ’ ̂ 13*943 \ 12*Q63,~ *‘

10

I t

10*640

10-025

10*226 11*827 11*110 j 10*683 11*133 11*405 .11*810 10*763 r 10*933 * 11*147 ' 13-7'0,8-p i 12*220 12*857 - 11*172 J 11*833 j 712*223 13*320 ] 11*600*1 *

IS

IS

10*210

9*688

9-888 11*067 10*713 { 10*447 10*787 |[ 11*077 11*503 10390 10*547 * 10*733 [ . 13*273 11*820 , 12*453 10*785 11*463 | . 11*852 ' i 11*210

14 0*850 9*517 10*826 10*802 ! 10*213 10*547 10*727 11*1%. J . 110*190 10*2531 ^ f . 10*583 ? 13*000 *1*2-167 - 10*513 11*140 . 11*560 . 12*533 j 10*87(3, J1 Pennmnent Rotation......... 8*688

.

8*562 8*604 10*143 9*283 9*625 . 9*770 . 9*620 10*340 9*380 L:. m m ‘ 9*893 ^ ^ r 6 6 7 11*083 9*332 10*140 . 10*780 10 *'923 - 9*567 i| Extremes of Temperature 8*ltol?*8 9*7 to 11*3 )10*4 to i t *8 JL2*5 to 13 2 9°*4 to loV :11*6 to 13*8 311*5 to 12°5 9-8 to i2°3 11*5 to 14*5 i f *3 to JlU|% 9*5 to 11°3* 13° 3 11*3 to 11*8 12*1 to 14% $1*6 to 12*0* > 9°*8 to 10°*3 :'l®5 to 12*4 ® l | o 13*2: 11°*3 to it i^ l 11*3 to 11.1

..................... i 3 4 6 1 ; 6 J 8 9 * 10 11 12 13 14 . 15 16 ' 17 18 19 ■ 20 ]

No. 21.

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