AW.9 1919
T H E J O U R N A L OF I N D U S T R I A L A N D ENGTNEERING C H E M I S T R Y
"mesh" means t h e number of meshes or openings per linear inch each way, measuring from center t o center of wire. I n the heaviest 4 X 4 mesh the opening would measure 0 . 1 1 5 in., whereas in the lightest the opening would measure 0.222 in. I n order t o get a space of 1/4 in. the size wire must be specified along with the size opening. For example, a wire cloth made of 0.083 in. wire with a n opening of 0 . 2 5 0 in. would be a 3 X 3 mesh. I t is well for users t o write the manufacturers for their catalogue giving table of sizes, openings, etc. The choice of sizes increases in the heavier .meshes and decreases in the lighter and finer sizes. There is very little difference in the size of opening and diameter of wire in the meshes finer than I O O X 100. A difference of 0.0001 in. in the diameter of wire would make a considerable difference in the finished product, both from a manufacturing and working standpoint. Under the heading of wire cloth, i t should be noted t h a t filter cloths and centrifugal linings are fast becoming leaders in the chemical industry. Wire cloth is and may be designed t o meet specific purposes. Several patents have been issued on filter cloths, and in each case there have been reasons for their design. The latest patent issued by the United States Patent Office' was on a cloth designed to compete with, and overcome the deficiencies found in, other filtering mediums. The factors influencing efficiency in filtration are rapidity, the life of medium, the cost of filtering the medium, the strength of cloth, the fineness of cloth, and the adaptability of the filter cloth t o any make of filter press. It is not the filter cloth which does the filtering; the filter simply acts as a retainer or backing in order t h a t a cake may be formed. This medium must be of a nature t o permit the filtrate t o pass through rapidly and t o retain the precipitate. In pressure filtration the cake really does the work, and the quicker the cake forms the more efficient your filter becomes. However. if the cloth becomes clogged, filtration ends or is much retarded. The cloth described in the abovementioned patent was designed t o overcome the difficulties met with in cloths which must be rolled t o get fineness of opening. I n rolling a piece of woven wire fabric i t is impossible t o keep equally sized and uniformly shaped openings, and strength is lost in the rolling of wire cloth. When fine overlapping wires such as occur in wire cloth are rolled, these wires are distorted by crushing between rolls. Strength is then sacrificed in order t o get fineness. This cloth replaces the old type fabric filter cloths, such as jute, hemp, and cotton, being stronger, more readily cleansed, and when made of Monel metal or pure nickel, alkali proof and impervious t o weak acid solutions. Monel filter cloths have stood the commercial use of solutions containing from 7 t o I O per cent sulfuric acid. The only case known t o the writer where Monel metal did not stand up in commercial use was in a press using cast iron plates and Monel metal filter leaves for the precipitation of 1
U. S. Patent 1,288,504, December 24, 1919.
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763
potassium permanganate. In this case the filter leaves rapidly decomposed because of electrolytic action set up. Microscopic examination of this filtering medium shows a n opaque surface, when the cloth is parallel with the table of the microscope. If, however, the cloth be turned a t an angle of 45'. small wedge-shaped openings are seen, the idea being t o have the contact surface of the filtering medium a practically tight backing for the quick forming of the cake, t h e wedgeshaped opening permitting a rapid discharge of the filtrate. As stated before, when an opening or mesh decreases t o microscopic size, water, because of its globular nature, must elongate in order to pass through i t ; if, however, the hole be rectangular, it will pass through more readily, and even better if the opening be wedge-shaped. I n this weave it is possible t o get twice the number of wires beaten up side by side t h a t would be theoretically possible; for example, 2 5 0 wires of a diameter of 0.004 in. laid parallel and in contact with each other, would equal one inch of space. Because of the weaving principle employed 500 wires are put in this one inch of space. These wires are spirally overlapped, giving a smooth, opaque, doublesurfaced filtering medium, the two sides of which are identical, and the openings in which are wedge-shaped, each one identical as t o shape and size. A cloth of this nature is very strong and easily cleaned, with a weight of about g ounces t o the square foot. This type of wire cloth is being used extensively as lining for centrifugals. Wire cloth has been one of the most important materials in the chemical industry during the war-time emergency. It has been used extensively in ordnance manufacture; explosives mills, cement, paper, glue, and pottery manufacture; dyestuffs production, drug houses, color works; food production; and last, but not least, ammonia oxidation.' NEWARK WIREC w ~ COMPANY n NBWARK, N E W JERSEY
DETERMINATION OF ANILINE IN DILUTE AQUEOUS SOLUTION By WALTERG. 0.CHRISTIANSEN
Received March 14, 1919
I n plants where aniline is produced the chemist in the works laboratory has t o determine the aniline content of the water from which the aniline has been separated in the rectifying house in order t o ascertain how much aniline is being lost in the water. Some days a dozen samples may be brought in, and if each is t o be analyzed by extracting a known weight of the sample with ether, drying the extract, evaporating off the ether in a weighed dish, and weighing the residue, considerable time is lost. It is somewhat shorter and more accurate t o add two drops of concentrated hydrochloric acid t o the undried ether extract in a weighed dish, evaporate the ether on a steam bath, and dry the residue of aniline hydrochloride in an oven a t about 50' C. The residue must not be heated t o a high temperature, as it decomposes readily. However, either of these methods takes between 3 and 4 hrs. THISJOURNAL,
11 (1919), 468, 541.
764
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
Vol.
11,
No. 8
I n attempting t o shorten the time factor, a coloriAnybody intending t o use this method of analysis metric method, based on the production of Runge’s ought t o make his own standard colors, following the violet when aniline is treated with a solution of calcium method outlined above. Below is a table showing hypochlorite, was investigated. As the work was how much ink was used in making up the standards carried out in a poorly equipped works laboratory, in my work. the apparatus used had t o be constructed from ma15 cc. of Water plus Per cent of Blue Ink’ Red Ink’ terials found lying about; this appears as an advanAniline Drops Drops CaCOaa tage now, for it taught us t h a t the apparatus costs 3 ‘/a 30 ... 0.5 almost nothing and is available everywhere. 0.4 2 18 ... 0.35 1 ‘/z 11 ... The colorimeter was made by supporting in front 0.3 1 6 ‘/z ... of a tungsten lamp a thick cardboard in which two 0.25 0 6‘/a ... 0.2 0 , 4’/2 ... slits 1/4 in. X 2 in. had been cut I in. apart. Above 0.15 0 3% ... each slit was a wire loop large enough t o svpport a 0.1 0 3 ... 16 X 1 2 0 mm. test tube so t h a t the latter hung di1 One drop of the blue ink = 0.0545 g. * One drop of the diluted red ink = 0.0541 g. 9 rectly in front of the slit. The test tubes used for the 8 I did not weigh the CaCOa added t o secure the required opacity. comparisons were 16 X 1 2 0 mm. and all of the same internal diameter; this was determined by putting PRECAUTIONS-TO secure the correct color t h e 2 0 cc. of water into a number of test tubes of this bleaching powder solution must be fresh and saturasize, and selecting those in which the water stood a t ted. The tubes of standard colors must be shaken the same height. before using. As Runge’s violet is not a permanent color a set ADVANTAGES-This method is rapid ( a dozen samof standard colors had t o be prepared, each of which ples can be analyzed in an hour), is easy, and accurate would correspond t o the color produced by a certain enough for plant control work. concentration of aniline in water. I n eight of the The following are check analyses run on samples of selected test tubes were put 5 cc. of aqueous solutions aniline water from an aniline rectifying house: of aniline containing, respectively, 0.5, 0 . 4 , 0 . 3 j, Colorimetric Aniline Hydrochloride Method Method 0.3, 0.25, 0 . 2 , 0 . 1 5 and 0 .I per cent of aniline. To Per cent Per cent 0.30 0.32 each tube I drop of dilute sodium hydroxide, 3 drops 0.35 0.39 of saturated aqueous phenol solution, and 4 cc. of 0.35 0.38 0.76 0.84 fresh saturated filtered bleaching powder solution 0.07 0.08 0.08 0.09 were added. After shaking, the tubes were allowed 0.70 0.69 to stand €or hr., each sample was diluted with 50 419 MAGEEAVENUE ROCHESTER, NEWYORE cc. of water, and the tubes half filled with the diluted solutions. Permanent colors corresponding t o the colors resulting from these solutions of known conAN IMPROVEMENT IN CASEIN MAKING’ centration were prepared as follows: A tube containBy J. .,I SAMMIS ing one of the above tests was hung in front of one Received April 9 , 1919 slit and another of the selected test tubes containing Large amounts of casein are now used in the manu1 5 cc. of water was hung in front of the other. To facture of water-probf glue for aeroplanes and other the water, red and blue ink and powdered C. P. calcium purposes. Lack of uniformity in casein as i t comes carbonate were added until the depth and opacity from the creamery has been found t o cause irreguQf the Runge’s violet were exactly matched. This larities in the finished glue, or t o necessitate variations was done for each of the above samples, and a set in the glue-making process, which it is desirable t o of permanent colors was secured corresponding t o avoid if possible. the above eight concentrations of aniline. The inks I n July 1918 a request was received by this deused were Stafford’s Commerical Bright Blue and partment from the Forest Products Laboratory, Carter’s Carmine Red Non-copying Ink, the latter Madison, Wisconsin, t h a t aid be given by the Dairy was diluted with a n equal volume of water before Department of the University so far as facilities would use. permit, in the study of these casein problems. T o determine the concentration of aniline in a n THE FAULTS T O B E OVERCOME A N D THEIR CAUSE unknown aqueous solution, take 5 cc. in one of the Variations in ash and acid contents in the dried selected test tubes, add I drop of dilute sodium hy- casein appear t o be the main causes of trouble in droxide solution, 3 drops saturated aqueous solution casein for glue making. The high acid and ash conof phenol, a n d 4 cc. of fresh bleaching powder solu- tents of many commercial caseins appear t o be due t o tion. After letting stand hr. dilute with 50 cc. use of excessive quantities of acid or t o insufficient of water, and compare a sample of the diluted solu- pressing or washing of the curd before drying. The tion with the standard colors in front of the electric older methods of precipitation were such as t o make light. If the resulting color is deeper t h a n the dark- thorough washing difficult. The curdling temperature est standard solution, 5 cc. of the unknown solution is commonly used (120-130’ F.) WRS so high t h a t the diluted with an equal volume of water, and this di- precipitated curd quickly gathered into large masses luted sample is tested as above and the per cent ob1 Published by permission of the Director, Wisconsin Agricultural tained multiplied by two. Experiment Station.
