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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 i V E E R I N G C H E M I S T R Y
and pestle .were washed and dried. A few days later some crushed pumice stone was required in the laboratory and t h e same mortar and pestle were used. A loud explosion resulted. The mortar and pestle were broken into many pieces and thrown violently about t h e room. One piece passed through a window scarcely shattering t h e glass. The room was filled with sulfur dioxide a n d fine particles of sulfur were scattered over t h e floor and table. .4n examination of t h e pieces of t h e mortar showed no traces of sulfur b u t quite large quantities of sulfur were found adhering to t h e fragments of t h e pestle. The wooden handle of this pestle had been sealed into the ball p a r t with sulfur. Evidently a small amount of t h e potassium chlorate worked into t h e crevice with t h e sulfur a n d caused i t t o explode when given a sudden jar.
Vol. 8 , S o . 6
a s they go. but filtration is slow and small differences in the decolorizing powers of charcoals are difficult to detect, even with the aid of a colorimeter. When t h e operation is repeated on a manufacturing scale, these small differences become magnified and may mean a considerable difference in the final product. T h e same argument applies, though perhaps t o a lesser degree, t o the testing of charcoal on argols solution and on various pharmaceutical products. The use of a n alcoholic solution of caramel, a s suggested by Laube, is open to t h e objection t h a t t h e solvent is volatile and t h e solution.cannot, therefore, be used a t high temperatures. If an aqueous, instead of a n alcoholic, solution of caramel he used, trouble is experienced in obtaining clear filtrates, and, moreover, t h e solution will not keep. An aqueous solution of a n aniline dye gives unreliable results owing t o t h e fact t h a t many charcoals on t h e market contain. appreciable amounts of soluble ash, and t h e alkalinity of this ash produces color changes which vitiate t h e results obtained. A method has been devised in these laboratories, which is very rapid and which enables charcoals to be classified with great ease a n d accuracy according to their decolorizing efficiency. A solution of Aniline Red, Soudan 111 (oil soluble), in kerosene is used. The strength of t h e solution is largely a matter of choice, but we have obtained t h e most satisfactory results with a 0 . 0 2 5 per cent solution ( 0 . 2 5 g. per liter). One hundred cubic centimeters of this soluF ~ ~ a v a n roP a BIOIIRN MORTAR A X D PRPTLE tion are measured into a 1 5 0 cc. beaker, 5 g. of t h e An examination of other pestles of t h e same type charcoal are added a n d t h e beaker placed on a boiling showed them to contain a s much as I O to 20 g. of sulwater bath in such a manner t h a t t h e beaker is entirely fur. enveloped in steam but does not dip into t h e water. This explosion might have been more disastrous had The charcoal is kept in suspension by frequent stirring not t h e mortar been used a t this time for grinding t h e a n d a t t h e end of ten minutes t h e beaker is removed pumice stone, as, in a few days i t would have been from t h e water bath a n d t h e mixture filtered. The used again to pulverize more potassium chlorate, kerosene solution filters very rapidly and comes and with t h e excess chlorate t h e explosion would have through clear a n d bright. I t s color is compared with been more violent. a scale prepared in t h e following manner: It certainly is not generally known t h a t t h e handles One hundred cubic centimeters of t h e kerosene of these pestles are sealed in with sulfur, for if it were solution of Soudan I11 are treated with I g. of a charcoal they would never he permitted in t h e laboratory. of average quality. The solution thus obtained is The pestle was of German make and whether or not they still employ sulfur for this purpose is difficult given the value IO. A second solution, obtained b y t o say. If a n y companies in this country are using treatment with 2 g. charcoal, k g i v e n t h e value 2 0 , sulfur for this purpose they should substitute in its a third, obtained with 3 g. charcoal is numbered 30, place some inert cement. Laboratories should bar and so on up to 100. The scale t h u s obtained is, of course, of a purely t h e use of this type of pestle until t h e sulfur has been arbitrary nature, b u t i t has, none t h e less, a real replaced by some safe material. meaning, Thus, if, by treating the standard solution UNlVBRSLTY 01 I'Glh-Ol% URBANA with j g. of charcoal according t o the method above described, a solution is obtained of the same depth of A RAPID METHOD FOR COMPARING THE DECOLORcolor as t h a t which has been given t h e value 70, it IZING EFFICIENCY OF CHARCOALS By LIONAID WICKBNDEN AND J o l ! ~\V. HISSLLR means t h a t 5 g. of t h e charcoal under examination will Received February 18. I916 do the same work a s 7 g. of t h e average charcoal. and The various methods in general use at the present thus possesses a 40 per cent greater efficiency. By using a solution of the strength indicated, t h e time for comparing the decolorizing values of charcoals, possess features which render them, for one difference in color between the solutions forming t h e reason or another, unsatisfactory. In most oil lab- scale is sufficiently marked for comparisons t o be made oratories, direct tests are made with the oil r h i c h without the aid of a colorimeter. I n order, however, is t o be treated. Such tests are satisfactory as far t o make our comparisons easier a n d more exact, we
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 the contrast between one color on t h e scale and 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 in. in diameter. Imthe center of which is a hole, 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 tint, as some deep purple-blue glasses are useless for t h e purpose. A t t h e further end of the 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 and 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) and no perceptible fading has occurred. I t is well, however, t o reserve a portion of the 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 the 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, and 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 and palm kernel oils. As regards sugar solutions, since t h e sugar chemist has other things to 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 in 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 than would be expected from the results obtained with t h e kerosene solution of Soudan I11 (see Table I--ilrgols Solution). Also, there are many charcoals on the market which give eminently satisfactory results with oils and other liquids, but 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 any color change has taken place. NOTE-Since the above article was written we have ascertained t h a t i t is no longer possible to obtain Aniline Red, Soudan 111. We have substituted for it Oil Red R S , manufactured by the Schoellkopf, Hartford & Ha;nna Co., Buffalo, N. Y . We use a solution of I gram of the Oil Red R h' per liter and find it to 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
The fact t h a t it is rarely possible exactly t o match the 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, the most important of which are the differences in luminosity, refractive index, turbidity a n d color composition of the materials t o be matched. The colorimetric determination of ammonia by the Xessler procedure or of phosphoric acid in soil solution by comparison with a standard solution of phosphomolybdate, or of either by comparison with standard colored glasses, are examples which well illustrate t h e differences existing in the 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
