June, 1916
T H E J O U R N A L OF I N D C S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
have devised a simple form of colorimeter whose effect is t o increase t h e contrast between one color on t h e scale a n d t h a t next above or below it. T h e colorimeter consists of a wooden box, 18 in. long, as shown in t h e sketch, painted black on t h e inside. Set back I in. from t h e front is a partition in t h e center of which is a hole, in. in diameter. I m mediately behind this is placed a color screen, whose effect is t o increase t h e contrast between t h e colors of t h e solutions being compared. This may consist of a glass cell filled with a very dilute aqueous solution of aniline blue (we use Indigo-disulfonic acid, N o . 692) or of a piece of blue glass. If t h e latter is used, care must be taken t o choose t h e right t i n t , as some deep purple-blue glasses are useless for t h e purpose. A t t h e further end of t h e colorimeter is a platform on which are placed t h e solutions under examination. As containers, we use square glass jars with screw tops1 of 2 oe. capacity, a n d t h e platform is made sufficiently wide t o accommodate three of these jars. The solution under examination is placed in t h e middle a n d a standard solution is placed on either side-the one of a slightly darker shade, t h e other of a slightly lighter. With a little practice. it is easy t o give a value
SI9
We have kept a solution of Aniline Red, Soudan
111, standing in our laboratory for several weeks) a n d no perceptible fading has occurred. I t is well, however, t o reserve a portion of t h e charcoal used for makTABLEI-DYE TESTVALUESOF CHARCOAL COMPARED WITH COLORRB)?OVAL TESTSBY LOVIBOND COLORIMETER TESTVALUE Per cent color CHARCOAL CSED Soudan I11 Removed from Oil LIOUIDS TESTEDKO. Origin Q Solution (Lovibond) Cottonseed
Oil., .
1 2
Animal
Animal
9 Anyma1 10 Veeetable 1 Animal 2 Vegetable 3 Vegetable 4 Vegetable 5 Vegetable 6 Animal 7 Veeetable Palm Kernel Oil. 1 Animal 2 Vegetable 3 Vegetable 4 Vegetable 5 Animal Areols Solution. . 1 Animal 2 Veretable (Yaturated) 3 Vegetable 4 Vegetable Vegetable 0 -4nimal ( a ) 0.8 g. charcoal per 100 CC.
Cocoanut Oil, , , .
Y~~
2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 0,s 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0,8(n) 0.8 0.8 0.8 0.8 0 8
8 10
28 38 48 50 7.5 7.5 80 85
IO 48 50 55 72 80 85 10
30
50 72 80
8
15 30
:.-: 80
3.0 5.7 12.3 19.4 27.2 27.3 33.9 34.0 34.4 35.0 47.0 65.6 65.6 66.8 71.2 76.1 78.5 26.2 36.3
41.3 46.3 46.3 46.0 2.5.0 46.0 87.0 on n 93.0
COLO.
ID.
a.rrirr
t o t h e tested solution with considerable accuracy. Thus, if a solution is found t o be between 50 a n d 60, i t is easy t o determine whether t h e value should be 5 2 , 54, 56 Or 58. As far as oils are concerned, t h e test with t h e kerosene solution of Soudan I11 appears t o be absolute. We have compared a very large number of charcoals from various sources, both of vegetable a n d animal origin, a n d in every case we have found t h a t charcoals which give equally high results with t h e kerosene solution show equally high efficiencies as decolorizers for cottonseed, cocoanut a n d palm kernel oils. As regards sugar solutions, since t h e sugar chemist has other things t o consider besides t h e removal of color, he will probably not be able t o substitute t h e kerosene test for his present tests with molasses. The method should, however, be of great service t o him i n enabling him t o eliminate charcoals which are not worth a more elaborate examination. We find t h a t animal charcoals, when used for decolorizing some aqueous solutions, show a higher efficiency t h a n would be expected from t h e results obtained with t h e kerosene solution of Soudan I11 (see Table I--ilrgols Solution). Also, there are m a n y charcoals on t h e market which give eminently satisfactory results with oils a n d other liquids, b u t are worthless for glycerine. I n testing charcoals, therefore, which are t o be used for either of these purposes, these facts must be taken into consideration. 1
Eimer and Amend, Catalogue 4142.
ing t h e scale of colors and t o make a test every few weeks in order t o ascertain if a n y color change has t a k e n place. NOTE-Since t h e above article was written we have ascertained t h a t i t is no longer possible t o obtain Aniline R e d , Soudan 111. We have substituted for it Oil Red R S , manufactured by t h e Schoellkopf, Hartford & Ha;nna Co., Buffalo, N. Y . We use a solution of I gram of t h e Oil Red R h' per liter a n d find it t o give satisfactory results. INDUSTRIAL CHEMICAL COMPANY LABORATORIES 521 WEkT 2
3 ST., ~ N~E W
Y O R K CITY
A NEW COLORIMETER By C. FRANK SAMMET Received March 14, 1916
T h e fact t h a t it is rarely possible exactly t o match t h e color of one liquid with another colored liquid or with colored glass often leads t o considerable error in determinations where colorimetric methods are used. These difficulties of color matching may be due t o a number of causes, t h e most important of which are t h e differences in luminosity, refractive index, turbidity a n d color composition of t h e materials t o be matched. The colorimetric determination of ammonia b y t h e Xessler procedure or of phosphoric acid in soil solution b y comparison with a standard solution of phosphomolybdate, or of either b y comparison with standard colored glasses, are examples which well illust r a t e t h e differences existing in t h e usual methods of colorimetric matching. Similar differences which are often very striking are also observed in t h e determination of t h e color of oils. With pure oil of turpentine, which is sold on t h e primary markets exclusively on t h e basis of its color, t h e color match is a matter of much commercial importance The arbitrarily fixed grades have given
52 0
T H E J O U R N d L 0 F I N D U S T R I A L A N D ENGILVEERIAVG C H E M I S T R Y
rise t o many disputes because of the lack of proper methods b y which t o match or reproduce t h e m . For ordinary purposes it has been found satisfactory t o use two polished bottom colorimeter tubes graduated in millimeters. These are vien-ed over a white background (a block of magnesium carbonate preferred) placed in a good light. T h e turpentine t o be standardized is poured into one t u b e t o a depth of 2 5 m m r a n d t h e tube covered with a S o . z yellow glass of t h e Lovibond scale. A S o . I yellon- glass is
1'01. 8. No. 6
mounted and may be placed in a n y position between the ends of the cell and t h e light t o secure a n y desired intensity. The cell is filled with a dark colored t u r pentine and the lights adjusted so t h a t the fields appear evenly illuminated in the eye-piece when t h e same is exactly half 11-ay between t h e two ends. The equal illumination of t h e fields can be effected most easily and accurately with a dark-colored turpentine. A slight movement of the eye-piece t o either side of the zero, o n the scale, is readily seen with a
\
placed over t h e t o p of t h e second t u b e which is filled with a portion of t h e same turpentine t o a depth where the colors of t h e two tubes match when viewed through t h e Lovibond glasses. T h e difference in depth between t h e turpentine in t h e tubes is t h e depth, in millimeters of turpentine, required t o match a S o . I yellow glass. Several other types of colorimeters were tested but none of these proved as conrenient or satisfactory as this method of matching in tubes. The method, however. has its defects in t h a t the fields are not adjacent, t h e a t t e m p t a t close matching of color by adjusting the height of t h e turpentine in t h e tubes is cumbersome and inconvenient, and the attention of the qbserver is diverted, especially a t t h e moment when t h e greatest attention is required in the matching. The colorimeter herein proposed is much easier t o manipulate, eliminates the above mentioned objections and permits accurate values t o be obtained. X long, narroTs, metal cell with glass ends is fitted with a n eye-piece which may be easily moved along t h e cell and its distance from t h e middle read of7 on a millimeter scale. A t the end of the eye-piece, and immersed in t h e turpentine, are suspended two prisms cut a t 45' angles. These prisms are encased on the bottom and sides with glass, leaving t h e ends and t o p uncovered. This is for t h e purpose of preventing the liquid from coming in contact with the reflecting. faces of t h e prisms and thereby preventing the reflection into the eye-piece. Shellac is the cementing material used. The light coming through t h e respectire ends of the cell is reflected b y t h e faces of t h e prisms into adjacent fields in the eye-piece. T h e illumination a t each end of t h e cell is produced b y a Too-watt: round. frosted bulb (LIazda), the light from which is intercepted b y a disc of daylight glasst' which is properly 1
Science, h-ew Series, 1'01. 42, A-0. 1085, page 534.
change of t h e position of t h e lights. This position of t h e lights when once determined may be fixed for all subsequent matching, provided t h e illuminating power of the lights does not change unequally. I t is a d visable for this reason t o check t h e illumination a t least daily. A No. I yellow glass of the Lovibond scale is then placed a t one end of the cell and a No. 2 yellow glass TABLE I-COMPARATIVE WITH
Sample h-0.
I......
hv ... , . 7, ., ... . .
-
---MACHINEOBSERVER B A 162 169 li3 166 162
16; 167 168 162 164
166 4 84 84 84 85 80
165 6 83 79 80
____
__ A v. . . , . J
...... . .
81
84
~.
83 4 62 61 60 64 66
63 63 59 63 59
4.
....
62.6 27 29 30 30 3i
61 4 31 29 32 32 28
I _
Av .....
5 , ,.. .. , .
?.v.. . . .
--
29.4 20 20 22 21 22
30.4 20
21.0
20 8
_
--
_ _-hi THE TUBES----
Mm. I55 157 168 175
I58 162 167 95 81 85 86 70 79
OBSERVSR A B Light Light Light, close Light, close Match Match Dark Dark Light Light Light, match Light, match Match Match Dark Dark Light Light Light, close Light, close Dark, match Dark, match Light Light Light Light
8! 4
____ AV..
R E ~ D I ~(TWO C S OBSERVERS'
E 22 21
_
20
Light Dark Light Doubtful Dark Dark. match
Light Dark Light Doubtful Dark Light, match
30 32
Light Dark Light Light Light, match Dark, match
Light Light, match Light Light Light Light
24 28 20 22 24 21 23
Dark, close Very dark Light Light, match Dark ~ Light Dark, match
Dark, close Very dark Light Light Dark Light Light, match
13
58 62 68 65 30 33 31 2i
is placed a t the other end. The eye-piece is moved backward and forward until a position is reached where the fields appear matched. Double t h e distance t h a t t h e eye-piece has been moved from the
June,
T H E J O U R ! V A L O F I N D U S T R I A L A N D E N G I N E E RI S G C H E M I ST R Y
I9I6
center is t h e actual depth of turpentine equivalent t o a No. I yellow glass. The details a n d operations can probably be better followed from t h e diagram. I n Table I the comparative readings in the cell and in t h e tubes on five different turpentines b y two observers are given. It will be seen t h a t t h e two procedures in t h e hands of experienced operators give essentially t h e same results. This demonstrates further t h a t had irregularities existed in t h e daylight glass they had no material effect, The cell with the eyepiece has a decided advantage. however. in t h a t matchings can be made more quickly and with less effort. Table I 1 shows t h e concordance between individual readings a n d also the average of five readings on each of fifteen different turpentines, b y two observers. TABLEI1 SAMPLEOBSERVER 1 A , ,, , , , ,.., 2
B . ,, , ,. , ,.. A . ........
3
B. . . . . . . . . . A , ,,, , , ,,,.
4
B.,, A , ,,
, ,,,, ,
,
, ,,,,. B . ,, , , . , , . . ,
.A . . . . . . . . . . B . , .., , , . . , SAMPLEOBSERVER 6 A , ......... B.,........ 5
7
A. . . . . . . . . .
8
A , ,. . . . . . . .
9
-4..
B . ,. . . . . . . .
B. . . . . . . . . .
........
B.,. . . . . . . .
A , ,........ B.,........ SAMPLEOBSERVER 10
11
12 13
A , ,, , , , , , .. B.,,,,,,,..
A , ,........ B . ,........
-4. ......... B.
14 15
.........
A..........
B... . . . . . . . 4.......... B . .. . . . . . . .
IKDIVIDOAL RE.4DIKG
154 155 116 116 143 144 64 62 56 56 66 69 51 50 52 49 52 48 26 26 27 24 32 29 17 14 16 14 16 15
152 158 116 122 145 150 64 66 51
154 159 112 118 146 146 65 64 55 52
154 153 114 118 144 144 65 66 54 52
148 152 117 120 152 143 65 62 51 51
54 ISDIVIDUAL READING 69 70 70 69 70 69 68 71 48 47 49 52 49 51 51 48 49 49 48 51 51 51 49 50 49 46 46 48 46 48 51 46 29 24 26 28 25 25 28 28 ISDIVIDUAL READING 25 26 28 25 25 28 27 26 30 32 28 29 30 32 28 28 14 16 16 14 14 16 16 16 14 14 16 15 15 15 14 15 18 15 14 14 16 15 16 15
Av. 152.4 155.4 115.0 118.8 146.0 145.4 64.6 64.0 53.4 53.0 Av. 68.8 69.4 49.4 49.8 49.8 50.0 48.2 41.8 26.6 26.4 AV. 26.2 26.0 30.2 29.4 15.4 15.2 15.0 14.6 15.4 15.4
T h e results indicate t h a t variations between t h e individual readings may be considerable, b u t t h a t t h e averages of five readings are well within t h e liinits necessary for this character of work. When a column of ~ j mm. o of turpentine is equivalent t o a No. I yellow glass a difference of I O mm. in t h e length of the column is equivalent t o less t h a n 0.07 yellow. This variation in the color scale seldom occurs between t h e averages of five readings. I n no case has the color between the averages of five readings exceeded 0 .OS yellow, which is well within t h e limits required in the grading of turpentine. The instrument is easily adjusted, a n d t h e readings are made rapidly and with little strain and annoyance, Though it has been used here only in reading the color of turpentine it is obviously equally adaptable t o colorimetric work when t h e standard glasses can be employed and when t h e solution does not a t tack the metallic cell, in which case t h e cell should be made of a resistant material. LEATHER AND BUREAUOF
PAPERLABORATORY
CHEMISTRY, W A S H I N G T O N
j21
A KJELDAHL FUME REMOVER B y F. G. MGRKLE
Received March 30, 1916
Anyone who has ever had occasion t o make Kjeldahl nitrogen determinations knows t h e irritating nature of t h e fumes given off in t h e early stages of digestion. Some of t h e common appliances for the removal of these fumes are t h e following: I-Closed hood with ventilator. -.-The Johnson digestion pipe, which may lead directly into a flue or into a tile receiving a spray of water as proposed b y Wagner.' 3-The invaginated pipette (Folin). 2 4-The bulb condenser (Sy). The strong suction in the Folin and also the Sy apparatus has a number of disadvantages: ( I ) It reduces the pressure on t h e liquid, thus increasing t h e time required for digestion; ( 2 ) it produces a partial vacuum which increases t h e tendency t o foam, especially with organic materials; (3) it causes spattering and blackening in t h e neck of the flask which is greater as t h e pressure on the surface becomes less. Bits of digesting material and drops of acid may be carried far u p into the neck of t h e flask necessitating attention during the operation. A ?SEW A P P A R A T U S
The apparatus illustrated b y Fig. I has been in use for a year in the course in General Chemistry of t h e
FIG.I
institution with which t h e writer is connected,and has given good results. It consists of a lead pipe ( A ) , ' 1 2 in. inside diameter, t o which are soldered as many 3-in. lead tubes, '/a in. in diameter, as there are Kjeldah1 flasks. Each small t u b e is fitted with a rubber stopper (C) t o accommodate t h e mouth of t h e flask. Caps ( D ) made by boring holes one-half way through rubber stoppers are handy t o plug u p unused tubes. One end of t h e main pipe ( A ) is plugged with a stopper, the other fitted with a bent glass t u b e which serves as a n outlet for t h e fumes. The whole is supported b y clamps as seen in Fig. 11. The pipe is easily bent so i t should be supported a t intervals of not more t h a n I ~ / Z t o z ft. I t is sometimes found advantageous t o lower the end of t h e pipe nearest the sink so t h a t there will be a fall of z or 3 in. in j ft. of pipe. This aids, somewhat, t h e outward movement of the fumes of condensed acid. T h e expanding fumes force their way slowly out of t h e tube ( F ) and may be disposed of b y letting it project a foot down the sink pipe which is washed with a small stream of water. 1 2
3
Chen.-Ztg., 36 (1912). 1438. J . B i d . Chem., 2 (1912). 503 THISJOURNAL, 4 (1912). 680
