Aug., 1916
T H E J O I ’ R N A L O F I N D U S T R I A L ISD E N G I N E E R I N G C H E M I S T R I ‘
but as the orange matures B normal amount of oil is formed. T h e results secured in the commercial tests on large lots of bright and russet fruit also indicate t h a t an equal amount of oil may be secured from each kind of fruit. CONCLUSIOSS
These preliminary results show t h a t there is a wide variation in t h e oil yield of Florida oranges under different climatic and cultural conditions, and t h a t ‘the question of variety is likely t o have.some bearing on the commercial production of orange oil. The oil content has not reached its maximum until. t h e oranges are fully mature, b u t t h e oil is present in commercial quantities before t h e fruit are ready for harvest. T h e occurrence of heavy rainfall during the season of harvest will cause a considerable decrease in t h e oil content. The presence of rust mite does not decrease t h e percentage yield of oil of t h e mature fruit, but may show some effect early in the season. BUPBIU 01 PLANTINDUSTRY. WISHING~ON
A NUMERICAL EXPRESSION FOR COLOR AS
j i l
the object of which is t o blend the light. The amount of light reflecled through the left-hand aperture is controlled by a shutter actuated b y a long levcr (C) t h a t moves over a scale ( I ) ) so divided into 1 0 0 divisions or parts t h a t at zero rebding the sliding shutter is entirely closed a n d at 100 divisions is wide open. By means of a t h u m b screw ( E ) t h e second aperture may be adjusted but through much narrower limits. T h e base of t h e eye-piece tube is equippcd with a sliding carrier (F) in which are mountcd red, green, a n d blue color screens, as well as one of colorless glass. T h e light under which t h e tests are made is received through a south window covered with tracing cloth, I n using the instrument two magnesia blocks are first placed directly beneath t h e reflecting mirror and in front of a vertical mirror ( G I . The lever operating the shutter is set at roo, t o give full opening of the left aperture, and the right-hand aperture adjusted by t h e t h u m b screw until the two halves of the field are of uniform intensity. This adjustment made, the mag-
GIVEN BY
TEE IVESTINT PHOTOMETER Ry O m KRSSSI A N Y G. C. MCNAIIGHTONI
Received May 27. 1916
The matter of a numerical expression of a definite shade of color is one on which various investigators have expended considerable energy with varying del grees of success. In almost countless phases of commercial and experimental work i t is extremely desirable t h a t there be a means b y which a n exact shade of color may be communicated t o others or so recorded t h a t this shade may be matched or referred t o when t h e original is not available. One readily comprehends t h e importance and practicability of an instrument which would give an accurate reading of color. So far as the authors know, there are but two instruments on the market, which would appear t o he practicable from a scientific and a possible mill standpoint, for measuring t h e depth of color of either liquids or solids. These instruments are known as the Ives Tint Photometer and Colorimeter. T h e tint photometer, being t h e more simple instrument, was used in these experiments. The original purpose of t h e experiments following was, ( I ) t o determine if color indications as shown b y t h e Ives tint photometer could be employed as a means of measuring t h e progress of beating, a n d ( 2 ) t o observe the relation between t h e numerical expressions for depth of color as read from t h e instrument and t h e relation of t h e shades as noted b y t h e eye. The t i n t photometer (Fig. I ) consists essentially of a form of telescope into which light from t w o sources is reflected, b y means of a mirror ( A ) , into two apertures, and focused b y a special lens into two semicircular fields. Each semicircle is uniformly illuminated by passing t h e light from t h e apertures, or slits, through a rotating wheel ( B ) mounted with lens, I
l o charge. Section 01 Pulp and Paper. Enginrcr in Poresf Products.
PIC.
I
nesia block on t h e right is removed and t h e paper ( H ) Using each of the color screens successively (i. e . , red, green, and blue) the amount of light entering the left aperture is decreased until i t is of t h e same intensity as t h a t entering the right aperture from t h e paper sample, or until the two halves of t h e field appear of one luminosity. The position of t h e lever when this matched condition of fields is obtained with each screen indicates numerically t h e proportion in which red, green, and blue light are reflected by t h e paper under test. For example, the white standards show 100 parts each of red, green, a n d blue, while a certain sample of a n undyed sulfite p i p e r gives readings of 7 j parts red, 7 1 parts green, a n d 67 parts blue. The sum of the three colors in t h e case of t h e white standard is 3 0 0 , while in t h e case of t h e paper it is b u t 2 1 j. For purposes of convenience it has been assumed t h a t in t h e latter case there exists a darkening effect of 8j parts of black (in 300). This factor of “parts black” which
to be tested is substituted.
T H E J O U R N A L OF I N D U 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
712
TIME OF B U T I I B
-
T,Ew8UIIM--WOYII
W R S
Fro. 3
Fro. 2
is secured, not b y direct reading of the, instrument, h u t by t h e subtraction of the sum of t h e three colors from 300, immediately expresses t h e relative brilliancy of t h e color examined although it conveys no idea of t h e t i n t if t h e other three readings are not given. The authors have found no difficylty in checking within one division (or p a r t ) t h e values secured in previous tests. The inventor of t h e tint photometer claims t h a t t h e personal equation becomes practically negligible in operating this instrument, and t h a t even a marked color-blindness does not affect t h e readings of t h e instrument. The tests were divided into two groups, ( I ) where depth of color was secured by prolonged beating effect, using t h e same amount of dye, and ( 2 ) where depth of color was obtained by different amounts of dye employed. I n t h e first group unbleached spruce sulfite pulp was beaten in a n experimental Marx beater of j o Ibs. capacity. The beater t u b is of concrete construction, with a specially formed trough for rapid circulation. The roll is 24 in. in diameter by 18 in. face, with a cluster filling of iron bars, and was operated throughout t h e experiments a t a, peripheral speed of 2,000 f t . per min. A very light treatment was given in order t h a t t h e comparatively short stock used would not be badly cut before t h e end of t h e operation. The treatment extended over a period of 24 hrs. Representing by zero the position of t h e roll above the bed plate when a very faint h u m could be heard as t h e roll turned in t h e empty beater, t h e following table shows t h e manner in which t h e roll was gradually lowered. Even a t t h e end of 24 hours t h e stock was Time st which roll
w_ lowered
At start At end
Position of beater roil
...........................
3 17 22
24
Vol. 8, No. 8
............................. ............................. ............
.............................. . . . . .............................
f0.10" +0.05" +0.01"
+0.002"
f0.000" -0.002" -0.004" -0.006'
roll raised
b u t slightly shortened a n d as i t still was rather far from pergamyn stock i t is probable t h a t greater differences in color tests would have been secured had
FIO.4
the stock been submitted to a more severe brush after the first few hours of beating. I n this group of tests a sample of the stock in the beater was removed every hour. For t h e various dyeings, pulp samples of 3 g. (dry) weight were employed which were secured as follows: A large sample of about 3.3 per cent density was pressed by the palm of the hand on a 70-mesh screen until no water dripped from it (about 1 2 per cent dry) and then thoroughly mixed. After determinations of moisture content of t h e pressed stocks were made, amounts equivalent to 3 g. (dry) were weighed out a n d bottled with IOO cc. distilled water. This method presents t h e difficulty of obtaining a homogeneous mixture of t h e pressed stock, b u t was b y f a r t h e best methodavailable. When ready for t h e dyeing, the pulps were washed out of t h e bottles with 2 j o cc. of water into enamelware cups 31/2 in. in diameter and 3s/s in. deep. In these t h e stock was agitated by a mechanical stirrer for a total of 20 min.-color, sizing and alum being added in t h e order named. I n t h e cases of t h e red a n d green dyes, respectively, 0 . 5 g. of Rhodamine B Extra and 0.j g. of Diamond Green G. N. were dissolved with the addition of a little acetic acid in a liter of water a n d a volume equivalent t o 0 . 1 per cent of t h e dry weight of t h e stock used for each sample. This gave dyeings of I Ib. per 1000 Ibs. of stock. The strength of the Crystal Violet was hut half of t h e others. Dilute solutions of size a n d alum were standardized and volumes equivalent t o I per cent of size (calculated as rosin) and I'/~ per cent of alum employed. The finished stocks were made into hand sheets on a special circular mold in. in diameter, pressed between t h e press rolls of a n experimental paper machine and dried between sheets of blotting paper on one of t h e driers. During the drying t h e hand sheets were turned frequently t o avoid t h e burning of the color.to the surface, and so cause an unevenness in depth of color on t h e two sides of t h e sheet. The wire side of t h e sheet was in every case used for. t h e color tests with the t i n t photometer. In making these tests all sheets of one color were ob-
Aug., 1916
T H E J O U R N A L OF I N D U 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
Fro. 5
FIG.6
served in consecutive order a n d continuously in order to avoid any great variation in lighting conditions. The results of t h e t i n t photometer observations are shown graphically in Figs. z , 3, and 4. in which t h e readings of parts red, green, a n d blue, as given by t h e . instrument, are plotted against t h e duration of t h e beating treatment. The calculated “parts black” also have been plotted in these figures. When comparing t h e depth of t i n t as determined by t h e t i n t photometer with t h e ratings exhibited t o t h e eye, it was noted t h a t an almost identical arrangement could be made. However, as t h e instrument does not distinguish a s readily as does t h e eye between very slight differences of shade, i t is necessary t o he very exact in t h e adjustments. Reference t o t h e cnrves in Figs. 2 , 3, and 4 will give t h e reader a n idea of the rather small differences in color between consecutive papers. While it will be noted t h a t many of t h e values obtained do not fall upon t h e smooth curve, this fact is not exceedingly serious, since t h e paper samples when viewed by t h e eye do not show a n absolutely regular progressive darkening t h a t should be expected, Such irregularities would occur if error had been made i n the rather involved method of sampling t h e stock, and where such a number of samples were taken it is not improbable t h a t errors were occasionally introduced. Slight variations from 3 g. (dry) weight would cause t h e stock t o assume a deeper or lighter tint, depending on whether t h e samples were too light or too heavy. Unfortunately, in trimming t h e colored samples t o fit t h e special paper holder t h a t comes with t h e instrument, t h e clippings were discardedconsequently t h e authors had no means of establishing t h e experimental error. The accelerated hydration a n d the corresponding darkening of the stock, when t h e brushing became more severe near the end of t h e beating treatment, are clearly shown in all of the figures. Fig. z is especially interesting in t h a t curves for the undyed beaten stock have been plotted on the same scale as t h a t used for t h e blue stock.
Fro. 7
113
FIG. 8
As is well known, t h e longer t h e stock is beaten, causing increased hydration, t h e less dyestuff will he required t o produce t h e same depth of color. This is well shown in all of t h e curves, as t h e same amount of dyestuff per 1000 Ibs. of stock was used, a n d the increased depth of color is due solely t o hydration. T h a t a color may be expressed in numbers-even though the’numbers allow a slight variation in s h a d e is far more satisfactory than t o attempt a description of t h e color. For example, a red may be on t h e yellowish cast tending t o approach t h e orange, or may be on t h e bluish cast tending towards the violet. The addition of any other primary color such as green would, in t h e case of red, not form a greenish red h u t would be a step towards darkness. I t is absolutely impossible t o record scientifically either a shade of red or t h e intensity of a red shade, by merely describing i t as either a light or dark bluish red or a light or dark orange shade. The addition of color in all practical dye work must be considered as a step towards darkness, and i t is common practice in t h e mill t o avoid mixtures of colors if brilliant shades are desired, especially in view of t h e fact t h a t t h e practical dyes used are never of a pure shade. A second series of color tests was made in order t o observe t h e behavior of t h e Ives t i n t photometer with various colors and intensities of colors. It will be remembered t h a t in t h e first series difficulty was met with, due t o a n almost exact similarity of many of t h e test papers. I n this second group of experiments all of t h e papers were made from one mass of pulp t h a t was removed from the beater after a light brush and tinted with various amounts of dye. The colors employed were “Diamond Green G. N.,” “Rhodamine B Extra,” “Crystal Violet,” and “Jet Black z R,” which were made up t o strengths of 0.5 g. dye in I liter of water, sufficient acetic acid being used t o prevent hydrolysis, and volumes of each used equivalent ‘h, 3 / 4 > I , I ’ / ~ ,2 , 5, and I O lbs. of dye per to 1000 lbs. of dry Stock. As before, t h e 3 g. (dry) samples of t h e stock were secured from t h e wet stock,
TJIE J O C R N A L OF I N D C S T R I A L A N D ENGINEERING C H E M I S T R Y
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after it had been squeezed by hand and its moisture determined as described in the previous tests. The manner in which the color, size and alum .n-ere added and mixed was similar t o t h a t formerly employed, with the exception t h a t the total time of stirring was increased t o 3 0 min., and t h a t an excess of size and alum ( 2 and z 1 i 2 per cent. respectively) mere used in order t o set the heavy shades. Up to about 2 lbs. of dye the back-waters were practically coiorless. The method of preparing t h e hand sheets from the dyed stock was identical with t h a t used :n the previous series. The gradations in .shade of these papers were very distinct. and offered no difficulty in making a visual selection of tho sheets in tlqe order of t h e strength of dye employed. The tint photometer also gave uniform readings of color vhich are shorm grapliica!!y in Figs. ~ 5 ,6 , 7 . and 8 where “parts rcd, green and blue” and also “parts black“ are plotted against the strength of dye used. K‘liile we are not prepared t o say just hoix- the readings of the three colors should be interpreted or horn matching a shade could be facilitated from them, it is very evident t o us t h a t with this instrument a shade or tint may hr: given a definite numerical value. Fonssr PRODLXTSLUBORATORV MADISOX. TT’isco~irx
NOTES ON THE DETERMINATION OF ALUMINUM By C . F. SIDEXER AND EARLPETTIJOHN Received October :4, 1115
The determination of aluminum in the form of aluminurn oxide. after precipitation with ammonium hydroxide. is frequently made. I s ordinarily carried out. there are several points in t h e determination t h a t might give rise t o variations in results. The purpose of this piece o€ work is t o determine the best procedure mTith regard t o some of these points. I n looking up the literature on’ the subject of this precipitation, considerable difference of opinion was found. The ordinary directions are t o boil until the liquid just smells of ammonia, though it was very early discovered’ t h a t a t this point ammonium chloride may have hydrolyzed t o such an exten; with volatilization of ammonia t h a t the solution is actually acid. In this case, of course. aluminum hydroxide would be redissolved and quantitative results could not be obtained. L. Blum2 worked on this precipitation and found t h a t ammonium chloride was decomposed in solution a t 100’ C. with loss of ammonia; he advises filtration when t h e liquid is still quite strongly ammoniacal. He also states. and many others veriiy his statement, t h a t ammonium hydroxide dissolves a certain amount of freshly precipitated aluminum hydroxide! which amount is considerably lessened b y the presence of ammonium salts. C. F. Cross,3 using ammonium hydroxide solutions of varying strength, found t h a t aluminum hydroxide mas dissolved a t the moment of precipitation. t h a t the amount dissolved bore no I p
3
Z anal. Ciiem.. 2 , 394;I, 59 I b i d , 27, ! 9 . Chew Y m s , 39. : 6 . .
T‘ol. 8 , NO.8
relation t o t h e concentration o i the ammonium hydroxide, and t h a t ammonium salts lessened t h e solubility of t h e hydroxide. Penfield and Harper,’ in testing for dissolved aluminum hydroxide, found t h a t it -sas not present in t h e filtrate but was present in t h e n a s h water. They tried using, instead of boiling water, a n ammonium nitrate solution, made b y neutralizing 2 cc. of pure nitric acid with ammonia, and making u p t o IOO cc. With this washing solution they claim t h a t t h e precipitation can be made from solutions containing larger or sinaller amoun.ts of ammonium salts, and t h a t no very great care is needed in adding ammonia On a number of points, exactly opposite opinions as t o procedure are held. Hillebrand, in his h‘A4nalysis of Silicate and Carbonate Rocks.” states t h a t , contrary t o the usual belief. aluminum hydroxide i!; noi. volatile in presence of ammoniuin chloride. and t h a - , for the determination, nashing free from chlorides is unnecessary. Washi:igton, in his “Rock ?inalysis.” and hIahin. “Quantitative I? nalysis,” take t h e opposiw view: and say t h a t a1uminu.m hydroxide must hi: washed free from eT-ery tracc of chloride or low rcsults will be obtained. STith regard t o tioiling t h e solu tion for precipitation, the same difference of opinion exists. Washington advocates boiling ifor not morc t h a n I min.) mrith a slight excess of ammonia. n-hile Handy2 boils for 2 0 min. under the Sam:: circumstances. For washing the precipitate, a m monium nitrate is frequently recommended, Treatiwell, Penfield and Harper, Yashington a.nd others making use of it. RenzI3however, found t h a t when alumin u m hydroxide was precipitated with ammonium hydroxide in presence of ammonium nitrate, a small quantity remained in solution. Fresenius, Handy and several others advise the use of hot water There is a similar difference of opinion as t o t h e ignition of t h e precipitate. Allen and Gottschalk4 found t h a t the highest heat of the blast lamp was required t o effect complete dehydration: precipitates heated t o 1100’ C. and cooled for half an hour were still hygroscopic. Handy5 also considers the oxide .i.ery hygroscopic and advises intense ignition. Cariiel1e)r and on t h e other hand, obtained complete dehydration by gradual heating t o 850’ C. The points which this paper covers are a s follows: I-To determine whether t h e precipitate need be washed free from chlorides before ignition. 2-To determine whether a n excess of ammonia has a n y solvent effect on the freshly precipitated hydroxide. 3--To determine whether water or ammonium nitrate solution is more suitable for washing t h e prccipitate free from chlorides. 4-To determine a satisfactory time for ignition L O constant weight. An aluminum chloride solution was made up from 1
2 8 4 6 6
A m . J . S c z . , 20, 9, 181. J . A m . Chem. Soc.. 18, 766-82. J . Chenz. Soc. (London). 2 (19031, 729 Am. Chem. Jour., 24 (1900). 292-304. J , A m . C h e w . Soc., 18, 766-82. J . Chem. SOC.(London),Trans.. 63,S i .
