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METHOD FOR THE DETERMINATION OF
FATTY MATTER IN SOAPS
I. R. WISHNICK
ARMOUR INSTITUTE OF TECHNOLOGY
19 14
668. 1
W76
Illinois Institute
of Technoiogy
UNIVERSITY LIBRARIES
AT 355Wishnick, I. R.A new method for thedetermination of total
For Use in Library Only
A NEW METHOD FOR THE DEtEBMINATION
OF TOTAL FAxiy ivIATT^E liJ SO/PS.
A THESIS
PKESEivTED BY
I.BOBEET WISHKICK
TO THE
PP.ESIDSUT AKD FACULTY
OF
APidOUE IKSTITUIE OF TECmJOLOGY
FOE THE DEGREE OF
BACHT^LOP OF SCIEiJCE IK CHEniCAL EKGIwEEFawG.
HAVIiNG COMPLETED TH^ ^E^CRIB^D CCfiJESi^
OF STTTDY IN
CHEJnCAL ^NGIKE^EIKGi
MAY -1914. PAUL V. GAlVffJ LIBRARY35 WEST 33RD STREET
^„„„^„^ 'HICAGO. IL 6061^
^:^<^ "-^--t^^r^-.^^cjt^
r"
c
.i»'
A
i^ - W-' ~" A'i '•!
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.H**!At It
.1.
INTEODIICTION.
Soaps ar? eir.ply mixtur-*" o^ the alkali
salts of the fatty acids. Th» process of
effecting combination of the -^atty acids with
the alkalies to farm the alVaii salts is ter-
med Baponification or soap boiling. It is
often necessary to know the amonnt of fatty
acids TThich were used in making the soap.
The pres'^nt method employed to determine the
fatty acids is a very teiious one and require «5
an experienced analyst to ob+"in check results.
It therefore, seemed practical to find a method
which was shorter ani simrjler, and accordingly,
the following work was undertaken.
EXPERII^NTAL.
The presi^nt recognized method of det-rmin-
ing total fatt3^ m.at^er in soaps consists essen-
tially of the following: a 10 grami saapi* of the
aoap ig transferred to a 500 cc. beaker, and dis-
solved in hot wat*r. Anv in-'oluble residue is
filtered off. Sulphuric acid is added to liberate
the fatty acids and the mat-rial is heated on the
• if* *0
.i'»c Ti f-»«" •It** .«f'"^l^ •tx'<
.J
flt*"^- *? 'c
"<? *!:o •* 1^' 'i . t»-o£; ' *o r:A';l*
on
*.
* "'^nti. ' Xo?
.2.
water bath until th« fatty acids separate in a
clsan laysT at th? top. At this point it is
advisable to add 5 grams of paraffin© so th^t
a firm cak« of the fats Trill b? -^orTned. Th#
weight of paraffin* is lat-r d«duct«d froTn th«
total w«iffht to ffiv« tfe« weight of fatty acids.
After th» paraffin* has mtlted, the beaker is
removed fror. the water >>ath and the fats allowed
to solidify. Remove the cake of paraf-^ine, and
fatty acids, wash it free of any ^ulphtiric acid,
and place it into a weighed b3aVer. The washings
contain sone •''ats.. ^^^hich are removed by a double
extraction with petroleTLTi ether. The ether extract
is pla:;ed in the beaker containing the cake of
f?tt7 ira-^ter, anf. the ^ther is evaporated off
over the water bath. The beaker is then placed
into a dr'^ing oven and dried at 100°0 to remove
any moisture. The drying must be done carefully
because if heated too high, the fats will decom-
pose, wheraas if too low a temperature is used
the moisture will not be roroved. Obtain the
weight of the whole and subti^.ct the weight of
the beaker and paraffine tc get the weight of
fatty acids in the soap.
^« •* • »• OffJ
.3.
The abovs method for toal fatty matter in
soaps has its drawbacks, viz,.l- The tir:e reouired
to complete the detarmination is V'^ry long be-
cause of the necessary- delay's 'T'hile drying the
fats to constant weight. (2) It is very difficult
to tell jnst how long the fats must be dried
be'^ore the fiaal weighing, and unless, one has
had some experieace with this he is liable to
male© an error here.
In order to overcome the objDction? to the
regular method Mr. John J. Schor^rrer suggested
that the Babcook method for the determiuat ion of
fats in milk might be successfully applied to
determine fats in soaps, and following his suggest-
ion the following work was undertaken:
Various samples of liquid and solid soaps
were analyzed by the present amd also by the pro-
posed method. The present method used has already
been described. The proposed method tried is very
similar to the ordinary Babcock method for fats
iH milk. It is as follows:
Use 18 gram samples for liquid soaps and 4.5
gram, samples for the solid soaps. This is ione so
that the fats liberated can be read easily on the
fli
1^ ' ^ l^jK /< ^ J?**" r**** <u,(#' n rtf. r <mr^ 4->» ' ; ' i t ' ^ i^ -?
»
• fTj c
'0 ...-
t-f^OP t -/
•11 Cot «i »*«'^ f-a
' if" !. .ff ^' 'Tcr • :ix-^"oi -'i^*''* * ^'*' not
.4.
necks of Babcock bottles. The readimg obtained
with liquid soaps gives the per cent, of fats
directly while V7ith the soaps wh^re 4.5 gram
samples were used, the reading must be multi-
plied by four to give the per cent. Transfer
the liquid soaps directly to the bottles Tvhile
the solid soaps are first dissolved in hot
water and theji transferred. Sulphuric acid is
BOW added ia sufficient quantity to liberate
the fatty acids, warm the bottles in hot water
for a w'^-ile and centrif^i.ge thex for ^our mintites
Add hot water to bring the fats o« the neck and
centrifuge again -^or one minute. Remove the
bottles '•lid read the per cent, of f?ts on the
neck while the fat is still "^arm.
The following table shows the results ob-
tained by the two methods, using 18 gram ox-
fractions of 18 gram samples in the proposed
method:
-^ '^ n %i» ••» riK
^ k. *.,
*rf» «>-^ wf* to .
> *
'"J I. i ' " n J
fft «i •«! •*» *f ft t
}i>«>rft#^
.5.
ho
cot)Ooin-<4«ooocoicco<D ca<!;• so LO to « u: lo 00 o c '-' <>2 «-* CQ k: ifl tofa: •• •
I I I 1 I
>
o <x) ( V2 K. ca •<* «o CD a> c\"» t^ -^t * CO o ;n oc.c+ •«;*< ca in -j;^ ai 00 w -4" c>- 'i> f-i o a c^ >- »-•
r.^ iH rH rH «-» si' CO J- >- t~~ ^ If <C tt: t£) t •
•O to W hO 02 -^ <£) O ia> CO iv. «* -^ CC C >. 00Hq). ,.,...<D K •^ ca lo -:!• CO CO c>a "* C^ ^O «H o CC C^ C-- r-t
+'OrHrH,H-l-»«:}IC0t-t>-t^CDir'tD'©'X) "^+>p.« or ^^ CO C3 50 <M -J* <X) ^ Oi Cvl C^ ^ * CO C IN CO& •••.
>. * ca ID "^ a. 00 CO 'i' i>- tc r-i o 00 fv- ^ r-«
+i r-lrHrHrH.H-sJIC0t~C-J>-tDU3'^"X>«; tJ»
. <c
l-l Vt>-«oci'5ioacvjC'-ttoir!-^c-<ooc »j«
tJ -t-- in 00 c; o c lo o- CI a> oi 00 'X) '-' t^ c~ ch3 «OO a, T' -^ r-( r^t -J< 00 CO <D »0 to f r-t fH r-t O- O UTJ
•< t O rH «H ^ .H -i ^ C-- C- C>- t^ <f Lf J>- tC !^ -^
0) p c^ o "O cr. K. CO c to «> CO o c- o o f. isPhS f>a <0 IN 00 00 C\ C-- CO to ID to >H Cj •^ c '^
cd^^•^^-Hl^^^^^-c-^^-^-tClc^-«Dl^- Tt<
ti!. D- C5 X) IC lO t^ O O O <X) O K tr <M is<D f-t .^3 L( } C- 00 O ^ CJ> 03 If rj" If C Oa >-l K)((;.•••••.•.•...«• «
•^fM-^JOC-QOOlC^-^tOr-lr-ICO^C •«*
»Hr-l,-<rHr-lTjil>.C^.l>.>.<Omj>-tOt- T^1
r-i i^ to -^ la 4^ «-lM
pH to 43 E
o rt ^ +3 ^ fe f^n: o« c = s: ^-1 > ^ +3 (D
^ pi b^HJ X m 1 ^^ -H o oT( pSse£S430M<D) oHfJn •r^Bo* V E O <D V bDtH cr /. c br43•H n-i OM>^-H-Ha>-PEEOMt^H -3 :q < n CO >J « ix, (0 «t < trj ©
>
•Hw»CTrHio«ot-oO(J>0'-'ca»Cr}'m<o05 rH l-H 1-H (—•<—( r-< r-<
I;
C^ 4k 40 4^ flft V M t
'
<
-• ^ < '. f-i- K- *^ t«^^
.
» -! t a t' » 0'
> :......;
• •'-••••>If « o -^
^
.b.
From the results im xable I it Ib seea
that the erroTB involved are alto?e-cher too
great and that uo defi»ite 3o«stamt cam be
applied ?irhich would irake the resiilts obtaime-'.
by the -proposed method sheclr with those of the
regular niethod. It appears thereforej that the
proposed method is a failure. However upon a
further study of the subject ^»i a critical in-
spection of the results so-iethinp- '^^as discovered
which led to a succeesfu.! solution o-^ the rrob-
len. It was noted tbat the Babcock bottles are
graduated to read the per cent, o-^ Butter fats
only; and since the -^at? found in soaps have a
different specific gravity than the butter fat,
it is natural that th-^ readings -"ot'ld be wrong.
To overcome this difference in specific oryavi-
tles it is necessary to know the specific era-
vities o-^ the fats in the soa-^s so that allow-
ance can be made -^or it. Acor'^ia^ly . the spe-
cific gravities o-'' the varior-.s fatty acids in
the soaps was determined as follows:
Pine? into a beaker a sufficient quantity
of soap to gi.¥e enoi-'^h fatty acids to •''ili the
tube for the float used with the West-^h^i balance.
~J.Ai - <'
"t
ftt i
• • *' -.-« - -+<
t^^f •:
•*x'
.< JC •' u '
t^ *t'^ Ot : O'- "
•'*
. I
,
Dissolve the soap im hot water, and add sul-
phuric acid to liberate the fatty acids. Waxin
the beaker until the fata separate i» a clean
layar at the top. Pun the material into a warm
separatinp' funnel, run of* th'=' heavier liquid
and finally allow the fate to run into the West-
phal tube. It is necessary '^hile t^kinp; the spe-
cific gravity to ^eep the fats perfentlv fluid.
This is done by having the tube imnersed in hbt
water. Keep a record o:'' the temperature at which
the specific gravity is d^+errined.
Kavin? deterr.ined all the specific gravi-
ties of the fatty acids in th^ soaps, proceed
to calculate the weicrhts of sample?! which ought
to give the correct per cent of fat? direct Iv
with the use of the Babcock bottle. These weights
are calculated as follows:
We know that th»» speci-^ic volume is invers-
ley proportional to the specific gravity. There-
fore, if the fatty acid has a greater specific
gx'avity than Bu'-ter fat, the volum-- occupied
by an equil w«i?ht of fatty acid will be less
than that occupied by btitter fat. In order to
allow for this a lar?rer size sample must be u-ed.
•rr • 'fl^J
'• r A
"J.
.8.
The 8iae of sampl© is obtained by Tmiltiplying
the ratio of the sT^ecl-^i'? ffravitie* of the
fatty acid to Butter fat by 16 or the norrnal
weight of sample tised in Butter fat deterrrina-
tions. ThiTS, if a certain fattv acid hao a
specific ftravifv of ,9"^ at 4<^°C . i^rhile BTitter
fat has r. specific ?:ravitv of ,9'"6 -^t 40°C!,
the calculated wei-rht of sample is jQSxlS'-
.90618.4768 ?ranii?.
If the speci-^ic gravity of the P^?.tty acid
is less th:in Butter fat a corre^pondinp: de-
crease in th* siz^e of snmple will bo necessary.
The ^ollowinp' t?ble showf=? the various spe-
cific gravities of the fatty acids, '^nd ?ives
the calculated wei^h+ of sami les to be used in
each case. It was asgun:ed that the specific
gravity of Bntt-^r fat was .906 at 40°C and
that a correction of .000617 be allow-d for
each 1°C for the sp*cific gravity of Butter fat.
»f«t
. *?«
'n n
f* ?.
~if-» -,
f* ^(n »
;-.'^ ' ~t'(\ f;
, 3f*T 'i•j riTj i:? ' u 4 ff"
.s.
T?
.J s» <
a J)
1 m
s 0-4
o
!•»
*f « < •><:; ^i 1 J.«* • •
.; *> (,i >\£ III
It
.iO,
On a comparison o"^ the per cent error in
table I with the sin:e of sanples calculated in
Table II, it i% evident why those errors appear
thus. We note that there is no de-^inite variation
in the error an": al?^ no de-^init'=' variation in
the sise of sar^'-les to '^^e "se % This is due "-o
the vari^'tions in the speci:^ic gravities of the
fatty acids in th^ so^ps. It is therefore, im-
possible to obt'^in =1 definite oainple which cau
be Tised ''or ail so^^s to -^i^-e correct resT^lts,
but the weight to be tised must be 'let ermine-^, for
each separat-^lv. Another point that can be not-
iced from the two tables is that th-s soaps which
rtj-n hi?h by the proiiosed ^etiiod are composed of
fatty acids w">^ose specific gravities ?-re lower
than that of b'jtter fats. This is '•^hct is to be
expected because the fatty acids havin?, a lower
specific gravity willhave ?. greater specific
volume ?.nd will there-Por^^ ?ive too hi»h a reaiing»
In order to correct 'or -f^his it v'ili be seen that
the calculated weight of sam.plcs in s'-'Ch cases is
less the.n 18 grms. which is the norm^.l weight to
bo ueed for butter fats. In tho«e instance* where
t->n ^ rf , <- .» -r 1 + -. •*•* /•\ .•• 4 ."j * •"'r <-'^- f. « *?' **
^0 •»••<» ''"»«?'•• • •>,«*"' ' rf* ""f*^^* f S* tt'lt
«*ff n* mt 1 ' ?«'^»
. "o n-.^s -{'"*t
-, ,-,j. - • » *r ***-t' f"-f-», "iff
.11.
the specific gravities are greater than bTitter
fat, th° re^'ult" in the Table I, show th-Jt the
proposed method gives low results, and the cal-
culated w?in:ht of samples to be used are all
more than 18 ?rms,
iJow, proceeded to fini out 'Whether the
above calculated weifrhts o-^ samples scttially
e-ive the correct ^;.er cent, o-'' ^its. Accordingly
repeated the analysis of each soap for toal
•'^atty Tr.dtter by the proposed method using tha
calculated weights of samples ep'-h time. The
'ollowlng reaults were obtained this ti:;e:
Ofit)u^n.\2o o o lo to C oo c om o c <# oV ri r-i -• to c ca o •-• ca c (.\j to oo m th o•H
O C3 C> O O O O O o o o oo oo oh,o oooooooocoooo ooC JO o cQ o 00 <\i cv3 lo 00 00 ro CO ca ca 00 toH in CO CO 'i) If? to if^ 'i* -^ y3 lo rH jn in <^ CD
c• a;
to+^at
43 _^
MO© „M oec x>p>-^coooooootoooc\j'30ooca'*M O
^1 Pt-^ rH i:jt ro r- 00 O"; cvj 'i* to r-l t-« r-t CO c -^t! *) o —• '-• rH 'H 'H * js ^- i>- IN CD in j>- vO r- •^
< cEH tUJ
* 03 C O O lir: fO c c> c c c ir O O X) O•-I W C^ CO Ol 00 <.NJ CO Oi C3 <D CD li' C »'J O '*:i
b itJ« tH r}l 10 ^ iX) 0» n rjl to rH .-I r-« 0^ C ^C M -H rH r-« r^ «;}< Pi {^ £^ J> CO XI i> CD t»- ^
p4i-< i.-vJtC-^int0c^000iOrH,-\J«O-5flCCDof lHr-<rH-lf-l«-tr-«o
<*•'. a i» D*. <tI .'3
u «*> -<
.13.
Discussion OF EEPULi'S with PE^O/.UtlOI^P?.
It is evident from an examination of the
above results that the proposed method is suc-
cossfii.l provided the correct wei~hts of samples
be calculated 'rom the deterr.in2.t10n of the spe-
cific p-ravities of th^ various fatty acids. The
results from soaps #12, 15 « 14 are somewhat of"'',
but, I believe that this is not ?. -^ault of the
method but that it is iue to th" character of the
soaps. Numbers 12, IS 6c 14 repref»»nt the laundiy
soaps; Fels-wSLptha, St^r, & Amber, which '"ontslned
a lot of resinous '""terisl end qvinn which hindered
the clean liberation of the •^'atty acid on the ad-
dition of sulphuric acid.
Some tro^ible wae had with most of th* laund-
ry soaps du* to the lar^e s^-^^unt of insoluble
material in the- and also to the presence of frums
which prevented the ^stisfactory liberation of the
fatty acids. This difficultv is overcom* by usiner
the alcohol extracts *'or fat determination. By
this mean*! the insoluble mat*ricl -^nd f^rms are
removed from th* sphere of action end the result
is a clean separation of the fatty acids. The use
of the al'^ohol e^tr^ct does not increase the time
appreciably, nor does it increase to s.ny extent
"^o ' f\ .'
,»^ ,, .. „ -f > '¥ '-f £.1 -> Ti r •
.':. "rf.'«!f -rff ^o fnoc ?•'
,c *r
f ^f ^
. i-
:* /t,x i i. I
**/> •^
•T "•O'" '^ "TT"
.14.
the Ipv.or needed for this determination as the
soi^ is usually evtracted with alcohol whf=>n an
analysis is rade on it for it* insoluble materi-
als and «o we can utilise thi«i extract "or the
fat deter'^inat ion. For very accurate work it
would b© necessary to take the readings on the
Babcock bottles r't the S3™9 tenr'er!=iture r?s that
at which the specific gravity was taVen, becanae
it was on that te=»sis that thw samples was calcu-
lated. However, for the ordinary analysis for
which this "^ethod is pro""osed the error involved
is sm?,ll ^-nou^h to bP noglectei as shown by the
following calculations:
Take ''or insfn^e soap ^ -^hose fatty acid
has a specific a-ravitv of .87^ at 50°C and i^hich
gave a per cent, o^ 72.8 at 5S°^. allowing .000 61
per 1°C for variation in sp. gr, w^ hrv? th9.t th?
sp. ?;r. of the fattv ^cid at B2°C s .8758.
Now "incc the specific volumes are inversely
proportional to the specific <?r9vities f'^e volume
or per cent, of fatty acid at ?>C°C, or the tem.per-
ature at -whi^h the s^^. gr. reading '"as taken is
expressed by X in the followino' equation:
ni •*! -<j"» ;r4 ,>*o ©re- at f.tV"-
f?'^'* 10' t*" - i[ tfa 1- "- r^ •rr- «!i'-
^ t-iff no *. *t
1- •»#>'•» vjt _TO^ ^^'
?-* Vl'-^VH'
!»«f
ff —mr f
rr-
f'l-r w ^ . fc -.'
.
'1.1*wo ^
* -^ « r .*^ r.'f*.
j'^rF ^0 ~V"=i« ^e ^ii-r'"j.'f '*'^i'
'?> t
Vf •T-'^flf
rtM5 ^« .^ ^^
'n " •i^i' •I"* • *^nm->-
.15.
.8738 s X
Solving for X w© have X - 72,,7io,
The above calculation "hows that for small
differences in the temperature at ^hich the two
readings "^re tiken, the error involved san be
neglected, but for lar?e differences the error
might be:^ome apprecioble. It is therefore, safer
to read the per cent at approx irately the same
teraperatiire that th? specific gravity is taken.
This I att?-.pted to do as closely as possible.
COKCLU^IOK.
The proposed r^ethod of determining total
fatty ratter in sor'."s is '"ithout "".oubt one that
can be depended upon to give results which are
accurate enough -^or ordinar'- cor.r.(»r4ial wor^'.
In cases where analysis must be turned out in
short order this rethod is -"^-r superior. It
ouo^ht to prove very useful in Ro?p fr'ctories
where the maxiufacturer already knowing the kind
of fat«> he uses know; his specific grravity and
therefore th-e weight of sampler to US'*, ani he
. xb<
can, thcr«, omit that part of the determination.
In cases where the sample supplied to be
analyzed is too small to yield s-u-P-^'icient fatty
acid to give enough r.aterial on which a specific
gravity determiniition can be ran, this n;ethod
could not be tised unless some idea be given as
to whether the *oap is made of ^ep'etable or
animal fats, when axi averag* weight mig?it be
used with fair accuracy although it is not ad-
visable to do so.
1 f " t. ~ - 4 £ ^r, ^ .
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