A N D ENGINEERING CHEMISTRY the concIusion t h a t some error was made in these determinations rather t h a n t o the assumption t h a t the iodine number of an oil may drop and then increase. Special attention should be focused on the rather moderate changes in constants shown b y corn oil, cottonseed oil, lumbang oil, sunflower oil, and hempseed oil (Nos. 1 1 , 1 2 , 1 5 , 16 and 17: respectively). These oils were all received in excellent condition and were perfectly clear and apparently free from moisture. These factors may have had much t o do with their keeping properties.
24
R A W LINSEEDOIL Untreated and Sterilized Iodine Sapon. Sp. Gr. No. No. Original Oil Not Sterilized Examined 1911 Original Oil N o t Sterilized Examined Nov. 1911 Original Oil Not Sterilized Examined Feb. 1919 Original Oil Sterilized Nov. 1914' Examined Feb. 1919
Acid No.
Refrac. Index
0.931
186.0
188.0
2.0
,.
0.933
185.4
189.6
2.8
1 .4867
0.943
182.1
192.3
4.8
1.4831
0.935
181.5
191.8
0.9
1.4816
RAW MENHADEN OIL Untreated and Sterilized 25
Original Oil Not Sterilized Examined 19 11 Original Oil Not Sterilized Examined Nov. 1914 Original Oil Not Sterilized Examined Feb. 1919 Original Oil Sterilized Nov. 19141 Examined Feb. 1919 1 Heated t o 105' C.
place in oil upon standing are due very largely t o autohydrolysis caused by the presence of either moisture or, in some instances, f at-splitting enzymes. Whenever oil is heated t o a temperature of 105' C. for a sufficient period of time t o remove the moisture, and then filtered, a moisture-free, clear and sterile oil will result. Such oil will apparently keep for a long period of time without showing any marked changes. TABLEVI-APPEaRANCE
O F OILS I N CONTAINBRS I N TO ANALYSIS
MARCH 1919,
PREVIOUS
0%
No.
TABLEIV
No.
7 61
0.932
158.0
187.0
3.9
..
0.934
156.3
193.7
16.1
1 ,4850
0.940
156.9
191.5
21.3
1.4802
0.938
156.2
190.1
5.1
1 .4802
Most interesting results were obtained with Oils a n d . 2 1 (American-grown tung oils). These oils have shown but very moderate changes in acid value, although both developed rather high saponification numbers, and Oil 2 1 showed a substantial decrease in iodine number. A comparison of t h e value of glass and tin for storage purposes is shown in t h e cases of Oils 2 2 and 2 3 . It seems rather curious t h a t the oil stored in tins should have shown more change t h a n t h a t stored in glass. This may possibly be due t o the action of t h e fungus growth t h a t was in 1919 observed t o be present in the tinned sample. Similar action on the same oil in t h e glass bottled sample may have been inhibited by t h e action of light. 20
TABLB V-MISCELLANEOUS TESTS Analyses made after allowing oils t o remain in glass bottles for nearly three years. No determinations were made a t start of test. Iodine Sapon. Acid Refrac. NO. Sp. Gr. No. No. No. Index 3.5 1.4696 8 7 . 1 192.4 26 Peanut Oil. . . . . . . . . 0.916 133.2 194.3 7.4 1.4767 27 Poppy Seed Oil.. . . 0.931 152.1 186.4 3.8 1.4791 28 Alfalfa Seed 011 . . . 0.926 0.8 1.4995 153.5 190.1 29 Tung oil^,., 0.937 Very heavy, granular deposit settled out, streaked 1 Source unknown. with fungus growth.
. . . . . .....
I n Table I V some data is given on the effect of sterilization of linseed and menhaden oils by heat treatment. The rapid rise in acid value shown by t h e unsterilized sample of menhaden oil, and t h e very moderate rise in acid value shown b y the sterilized oil would indicate t h a t properly treated oils may be made more or less immune from changes of a n undesirable nature. I n the writer's opinion the changes t h a t take
Very slight sediment Vwy clear 3/4 White sediment a t bottom. Globular-like oxidation a t surface 4 =/3 full Completely solidified t o white mass, crystalline a t surface 5 1/3 full Very clear 6 '/a full Highly viscous. Clear 7 Q/s full Clear. Slight film a t surface 3 / 4 full 8 Highly viscous 3/4 full 9 White sediment a t bottom. Globular-like oxidation a t surface 10 ' / 2 full Clear ' / 2 full 11 Slight white sediment a t bottom. Clear 12 '/4 full Heavy white sediment a t bottom. Clear 2,'s full 13 Dark sediment 2/3 full 14 Clear. Film a t surface 2/3 full 15 Very clear 16 '/3 full Very clear I / 3 full 17 Very clear '/a full 18 Dark sediment a t bottom 19 l/sfull Dark sediment a t bottom 20 3/4 full Lower third of oil completely solidified to white mass. Upper part clear 21 '/s full Completely solidified t o white mass Clear. I n can 9/10 full. Clear, but sllght fungus 3/a full 22 streaks 23 */a full Completely solidified t o milk-white mass Very clear '/a full 24 Very clear 25 '/a full 26 S/4 full Clear 27 full Lower third of oil black mass with white specks throughout and a blanket of milk-white granules a t t o p T h e precipitated foots and curious form of oxidation products a t the surface of the fish oils was of a distinctive nature. T h e solidification of the tung oils t o a white, granular mass is characteristic of these oils when exposed t o light for long periods. This condition makes necessary the determination of refractive index a t 60' C. T h e matter, settled out from the corn and cottonseed oils, was very flocculent and white. 1
'/4
2 3
3/4
full full full
There was unfortunately no analytical data originally obtained on the samples of oils shown in Table V, b u t a t the end of nearly three years' storage the constants would indicate t h a t but slight changes have taken place in t h e oils, with t h e exception of tung oil. This sample was from a n unknown source and may have been adulterated. THEINSTITUT@ OF INDUSTRIAL RESEARCH WASHINGTON, D. C.
WIRE CLOTH AND ITS ADAPTABILITY TO THE CHEMICAL INDUSTRY By ALVIN ALLEN CAMPBELL Received June 11, 1919
Under t h e heading of wire cloth there may be numbered over ten thousand different meshes, sizes, and grades. The term wire cloth even t o the mind of large users is hardly appreciated t o its full extent. The wire cloth industry was started in Scotland many years ago, and t h e first plant in t h e United States was started a t Belleville, N. J., some I O O years ago,
,762
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
by some Scotch immigrants. There is still in operation one of the old original hand looms. I n order to give an idea of the possibility of weaving from wire a square mesh, the following comparisons are given: A mesh of 2’/2 in. X z1/2 in. can be made of as heavy rod as I in. diameter and can be made of as light a wire as 0 , 1 7 7 in. There are listed fourteen different sizes of rod and wire in between these two limits. The mesh then gets finer until it reaches 2 5 0 meshes t o the linear inch, fabricated from a wire 0.0015 in. in diameter. The wide range of differences can readily be seen from the above statement. I n many instances perforated metals are used as backings for tank strainers, centrifuges, filters, malt floors, washers, etc. The heavier grades of wire cloth are fast replacing this material for the reason t h a t the air space is greater in comparison t o the area of the screen than t h a t of perforated metal. The term “air space” is the technical term in the wire cloth indust r y for the opening in the mesh. Wire cloth has the advantage over perforated metals from other viewpoints. I t is stocked in a greater variety of metals, and can be used for sizing materials, because of the very great range of openings and their uniformity. Wire cloth has long been used in the paper industry, and the majority of manufacturers in the United States still confine their efforts t o the manufacture of Fourdrinier wires or paper machine cloths. Fourdrinier wires range in mesh from 40 t o 90, although some tissue mills use wires as fine as I O O mesh. The manufacturers of the United States had been rather backward in the fabricating of wire cloths finer than I O O meshes t o the inch until about 1912, when some experimental work was started in weaving a piece of zoo-mesh cloth for the Edison laboratories. After overcoming many difficulties, a piece of zoo-mesh cloth 34 in. X IOO f t . was completed, using Monel metal wire of a diameter of 0 . 0 0 2 1 in. This cloth was later used for filtering wax. From t h a t time on Europe has had American competition. The United States Bureau of Standards in their investigation of testing screens say t h a t it had been impossible for American manufacturers t o successfully manufacture meshes finer than IOO mesh t o the inch, and t h a t meshes of the finer nature had t o be imported from Germany, France, England and Scotland. While all American manufacturers listed the fine cloths in their catalogues, they were not American-made goods, in fact, there are still foreign-made goods sold on the American market. Probably 80 per cent of all the wire cloth. especially the fine wire cloth imported from Europe, came from Germany, while the other three countries furnished the balance. A great number of the German manufacturers were located in Alsace-Lorraine, which will of course now be rated as French. The finest wire cloth on record is 350 mesh, but early in 1914 a firm in Elberfeld, Germany, started t o make 400 mesh. If this was accomplished none of it ever came t o this country. The finest square mesh manufactured in
Vol.
11,
No. 8
the United States is 2 5 0 mesh. All finer is imported material. All of these fine cloths are confined t o a standard, as t o size of wire, size of opening, etc. The standard is fixed by the United States Bureau of Standards. American manufacturers do their utmost t o keep up this standard and are constantly in touch with the Bureau. A word as t o perfect cloth. If a wire cloth is sold as 2 0 0 mesh, i t should measure, within the allowance specified by the Bureau of Standards, 2 0 0 mesh by 2 0 0 mesh, in other words, 200 each way. There are, however, cloths sold on the market as a given number, for instance, as 2 0 0 mesh, which may measure 2 0 0 one way but the other way may measure 185 t o 190 mesh. This t o the eye is not noticeable, but in work does not give the desired results. The exporters were very fond of sending fine wire cloth into this country, giving it a number which was mistaken by the American buyer as the mesh. For instance, French and German manufacturers would give the number 2 0 0 t o a cloth which, when counted, would total only 190 each way, but was bought as 2 0 0 mesh. It cannot be said t h a t this was a deliberate fraud, but in a great many cases the exporter would “get away with it.” As an example of the necessity of a cloth being perfect, the following test may be tried: Solder a piece of square mesh 2 0 0 X 2 0 0 in the bottom of a funnel and pass some hydrocarbon mixed with a little water through it. The result will be t h a t all of the water will stay on top of the mesh and the hydrocarbon will pass through. I€, on the other hand, a piece of mesh 2 0 0 X 180 is used, the water will pass through as readily as the hydrocarbon. The explanation is, t h a t the water has a specific gravity different from t h a t of the hydrocarbon; being heavier and globular in nature, i t is held back by the square opening, while the lighter hydrocarbon readily passes through. In the second test, where the mesh is rectangular, the lighter hydrocarbon passes through as readily, while the heavier water, because of its globular nature, elongates and passes through quite as fast. The user should remember t h a t there is a wire cloth available for each individual use, and t h a t some of the larger manufacturers maintain special testing laboratories in order to assist t h e user in finding the best mesh for his use. As before stated, wire cloth covers many meshes, weights, etc.. and in addition i t can be said t h a t no matter what the trade name may be, if i t is a woven wire fabric, i t is wire cloth. A few of the trade names follow: Metallic filter cloth, brass lawn-fly screen metallic bolting cloth, wire gauze, platinum gauze, washer wires, Fourdrinier wires, Dutch cloth, centrif ugal liners, wire mesh, etc. It is well t o investigate and know wire cloth t o some extent before ordering. There are two different ways of measuring. If an operation calls for a l/4-in. square opening, i t would not be correct t o order 4-mesh wire cloth, as 4 mesh is made of thirteen different diameters of wire, ranging from 0.13 j in. as the heaviest size t o 0 . 0 2 8 in. diameter as the lightest size, The term
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.
'
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.
