May, 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 ENGINEERING C H E M I S T R Y
U. S. Metals Refining Co., Chrome K.J. Samples of precious metals. Walru5 Mfg. Co., Decatur, I11 Laboratory desks. John Wiley & Sons, New York. Technical books.
Members a n d guests t o t h e number of 206 left Urbana-Champaign on Friday morning a t 8 o’clock for Danville. A special t r a i n was furnished b y t h e Illinois Traction System. Members of t h e Chemistry Faculty a n d of t h e S t a t e Geological Dep a r t m e n t pointed o u t a n d explained t h e geology a n d t h e plants of interest as t h e y were passed b y t h e party. T h e cars stopped first a t t h e Hegeler Zinc Smelter. This plant began operations in August, 1908, with 1800 retorts: a t t h e present time there are 5400 retorts in operation with a daily production of 7 j tons of spelter. High-grade Joplin blende concentrates are roasted in Hegeler multiple hearth kilns, t h e sulfur dioxide being utilized in sulfuric acid manufacture b y t h e lead chamber process. T h e acid systems have a daily capacity of I jo tons of HzS04 ( 6 0 ” Be.). The roasted ore is mixed with anthracite slack coal a n d carried b y belt conveyors t o t h e charge bins in t h e furnace building. T h e distillation furnaces are of t h e Hegeler producer-gas fired t y p e a n d have 900 retorts each. Boilers are installed upon some of t h e furnaces t o utilize waste heat. During t h e morning visit all t h e operations connected with t h e beginning a n d end of t h e 24-hour cycle for each retort were seen, including drawing a n d casting of t h e zinc, removing a n d cleaning t h e condensers, removing residues from t h e retorts, recharging t h e retorts, setting u p a n d closing t h e ends of t h e condensers. The p a r t y was entertained in Danville b y t h e Chamber of Commerce, who furnished a most delicious luncheon, cafeteria style, consisting of a n enormous variety of cold meats, salads, relishes a n d sandwiches, with steaming hot coffee I n the afternoon t h e parties divided, one section going t o a glassworks, which is making window glass, a n d t h e other t o t h e Carbon Hill Stripping Mine. I n this mine a j - y a r d steam shovel with a 90-ft. boom is operating along a face from a quarter t o a half mile long, taking out a strip from 28 t o 3 j feet wide, with a n overburden from 8 t o 45 feet in thickness T h e coal seam averages about six feet in thickness a n d t h e product is of good quality. Of unique interest t o chemists is t h e pyrite washery operated a t this mine. m-hich runs through i j tons of material per d a y , yielding 3 j tons of high-grade pyrite. This is sold t o acid manufacturers as “coal brasses” on a guarantee of 4 7 per cent sulfur. T h e company also
owns t h e Mission Field Mine, t h e oldest a n d most extensive stripping in t h e district. This was seen from t h e train on t h e return t r i p t o Champaign: it has been worked for over 2 5 years a n d is now exhausted: underground operations are continued, however, b y means of slope and drift mines. T h e p a r t y t h e n proceeded t o t h e plant of t h e Western Brick Company, which manufactures a number of different kinds of brick a n d tile. T h e shale used is taken from t h e s t r a t a lying above t h e coal seam in t h e company’s strip mine adjacent t o t h e plant. The company has two other plants in t h e vicinity of Danville. I n all t h e y operate 76 kilns a n d have a n annual production of I O O million brick. T h e number of ladies a t t h e meeting was not as large as usual. The ladies of t h e town a n d t h e ladies of t h e faculty, under t h e leadership of Miss I s a bel Bevier, were especially active in looking after those present. On Tuesday afternoon, Mrs. S. T. Busey and Mrs. David Kinley were hostesses a t a reception i n t h e Woman’s Building; afterwards automobiles were available for excursions through t h e grounds. All t h e exercises of t h e regular program were attended by t h e ladies and their guests. On Wednesday a reception a n d luncheon at t h e Champaign County Country Club, with Mrs. B. F. Harris, LIrs. D. P. McIntyre a n d Mrs. Stanley Boggs a s hostesses, was given i n honor of t h e visitors. On Thursday afternoon t h e Woman’s Building was open for inspection, a n d Mrs. Bartow a n d Mrs. Green were hostesses. T h e ladies present expressed themselves as not only well entertained, b u t considerably educated b y their visit, as t h e Home Economics Department is a n exceedingly complete a n d efficient one, a n d t h e Woman’s Building, with its wonderfully complete equipment, offered many interesting suggestions t o home-makers, T h e visiting members were amazed a t t h e efficient manner in which arrangements h a d been made t o carry out smoothly t h e various features of t h e program; everywhere one noted t h e pains t h a t h a d been expended on t h e plans t o make comfortable in a small town t h e large number of guests present. T h e Local Committees, headed b y Professor Edward Bartow, a n d made u p almost entirely from t h e faculty of t h e Chemistry Department, can be congratulated on having engineered our most successful a n d largest general meeting a n d on having furnished another illustration of t h e executive ability of t h e American chemist.
ORIGINAL PAPERS
1
THE DEVELOPMENT OF LOW EXPANSION GLASSES‘ By E
C SULLIVAN
thermal expansion coefficient in glass is useful mainly because i t carries with it t h e property of wTithstanding sudden heating a n d cooling without fracture. The expansion is one of six factors XxThich determine t h e ability of t h e glass t o resist such t r e a t m e n t ? LOW
1 2
Presented before the Society of Chemical Industry on March 24. 1916 Winkelmann and Schott, A n n Phys Chem , 5 1 (1894), 730
399
1
This coefficient of thermal endurance is proportional directly t o t h e tensile strength a n d t o t h e square root of t h e heat conductivity a n d proportional inversely t o t h e expansion coefficient a n d t o t h e modulus of elasticity a n d t o t h e square roots of t h e specific gravity a n d of t h e specific heat. Thanks t o t h e pioneer work of Otto Schott of Jena, Germany, we know t h a t t h e expansion can be varied Over a very wide range’ regarding quartz glass a n d speaking only of glasses
400
T H E JOCR,VAI, O F I L V D C S T R I A L AiVR E i V G I L I T E E R I S G C H E M I S T R 1 7
which can be melted and worked by t h e usual methods, the expansion of glass now can be varied in t h e ratio of six or seven or more t o one. There is no reason t o think t h a t a n y such range is possible with respect t o the other properties mentioned, Ordinary lead glass has a linear expansion coefficient of 0 . 0 0 0 0 0 9 2 while lime glass is somewhat higher. Glasses are made without difficulty having expansions as high as 0.0000130 or 0.0000140, copper b y way of comparison being O . O O O O I ; j, iron 0.000013. Going down t h e scale we find t h e Jena normal thermometer glass 19’” a t 0.000008 j , and Jena borosilicate thermometer glass 69”’ at 0.0000064. The well-known brands of laboratory ware are made of glass having expansion from o . o o o o o j j t o 0.00000jj. A glass recently de\-eloped in America which is finding some application for laboratory ware and for culinary utensils, although the bulk of i t goes into battery jars and lantern globes for railroad purposes, has expansion of 0.000003 2 This expansion is ,practically t h e same as t h a t of t h e best porcelain and t h e glass makes a satisfactory permanent seal with porcelain. Quartz glass has a n expansion of 0.0000006 t o o.oooooo7. The glass maker who endeavors t o reduce the expansion of his glass soon encounters t h e serious difficulty t h a t as expansion decreases, fluidity is likely t o decrease also. T h e glass of low expansion tends t o become very stiff a t the ordinary glass-melting temperature. This is obviated t o some extent b y t h e use of boric oxide, b u t this has its limitations not only because t h e expansion of t h e glass passes through a minimum and begins t o increase again as t h e amount of boric oxide is increased, b u t also because boric oxide, used in large quantities, affects t h e stability of t h e glass very injuriously. One successful low expansion glass containing a n unusual percentage of boric oxide was sloi?-iy b u t completely soluble in water. Jars of this glass l , / * in. thick went t o pieces with water in t h e m in t w o or three months, while acid a t e through them in a few days, and yet t h e glass was perfectly satisfactory for certain service and hundreds of tons of it were used. Two glasses of equally low expansion will not, however, in genera1 have precisely equal viscosity a n d it is b y taking advantage of slighz differences in viscosity when t h e expansions are alike t h a t t h e most favorable relation between expansion and meltability is worked out step b y step. T H E E X P A N S I O N is measured b y t h e method of Holborn and D a y in a water-jacketed electric furnace consisting of a horizontal porcelain t u b e wound with resistance wire. Within t h e t u b e is supported horizontally a rod of t h e glass t o be measured, about 3 mm. in diameter and 2 5 cm. long and pointed a t each end. Directly beneath the pointed ends of t h e rod are vertical openings in t h e bottom of t h e furnace through which, b y means of totally reflecting prisms, small telescopes can be sighted on t h e points. Crosshairs a n d a micrometer screw on each telescope fix t h e position of t h e extremities of t h e rod and SO its 1
Sullivan and Taylor, THIS J O U R N A L , 7 (191.51, 1064.
1-01,8. SO.5
length. The temperature cold is determined h>means of a thermometer thrust into the end of the porcelain tube and hot by means of platinum platinumrhodium thermocouples which extend haif t h e length of the tube. The temperaIure is carried usually 1.0 3 j o o C. or 400’ C . and t h e expansion coefficient as determined is accurate t o a few tenths of one per cent which is adequate for t h e purpose. A more direct comparison of coefficients of thermal endurance which requires less time t h a n the expansion measurement, is made by heating eight or ten glass rods in a i-erticai electric furnace to a definite temperature and then dropping the rods all a t once into water b y remoT-a! of the supporting asbestos slide. The temperature a t which j o per cent of the rods fracture is a figure which for purposes of comparison represents t h e coefficient of thermal endurance of the glass in question. T H E S O E T E N I X G T E M P E R A T U R E is measured by 2 method similar t o t h a t described b y Dr. Schaller of the Jena laboratory.’ -4 thread of glass approximately I mm. i n diameter and 2 3 cm. long is suspended vertically through a small electric furnace in such a way t h a t t h e thread is heated through t h e upper 9 cm. of its length. The temperature is raised and noted a t short intervals and as t h e thread elongates of its own weight t h e movement of t h e lower end is read off on a scale and plotted against the time. The momeni a t which t h e thread was elongating a t the rate oi I mm. per minute is read from the c u n e a t a glance and the temperature of t h e upper part of the thread a t t h a t moment is taken as the softening point of he glass. This is! of course, a n arbitrary point. This method gives us t h e viscosity a t low ‘;emperatures and is useful in determining t h e sealing qualities of a glass. I t does n o t , however, give us as much information as we should like regarding t h e viscosity a t high temperatures, .rc.hich goes far toward determining t h e ease of melting. Behavior when worked in a hot flame gives some indication on this point. T H E W O R K A B I L I T Y of a glass depends on its freedom from tendency t o crystallize, on its viscosity curve, and on its surface tension. The glasses which are most satisfactory in the hands of t h e glassworker are those which remain pasty through a n extended range of temperature. I t is this possession of a viscosity curx-e which is low at comparatively low temperatures and yet does not decrease rapidly as the temperature rises which gives lead glass its advantage in t h e construction of electric incandescent lamps and other apparatus. The lead glass after being sealed t o wire or other glass as it cools remains soft to a low temperature and thus can yield t o stresses caused b y uneven cooling or unequal expansions and can cool without strain. Lime glass is more like a crystalline substance, which remains rigid until a definite temperature (its melting point) is reached, when it a t once becomes very fluid. The viscosity curves of such glasses cross, and the lead glass which is softer, t h a t is, less viscous t h a n t h e lime glass a t low temperatures, is harder or more viscous 1
Abegg, “Handb. d. anorg. Chem.” Bd. 111. Abt. 2 (19091, 373.
M a y , 1916
T H E J 0 L : R N A L O F 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 E’
a t high temperatures. This is easily shown in t h e pull-test, which is a simple method used b y t h e glassworker for comparing t h e working qualities of glasses. T h e two glasses i n cane or t u b e of t h e same diameter are sealed together a n d heated as nearly alike as possible a n d are t h e n removed from t h e fiame a n d slowly pulled o u t a few inches, t h e joint being first slightly blown u p in t h e case of tube. The harder glass will h’ave greater diameter a t t h e joint t h a n t h e softer after pulling out. This is a sensitive a n d very useful method for checking u p t h e uniformity of different lots of glass. I n this test as already indicated t h e result in t h e case of glasses which differ widely in composition may depend on t h e temperature of pulling. A lead glass which appears softer t h a n a lime glass a t low temperatures may t u r n out t o be harder t h a n t h e same lime glass if t h e test is made quickly w h e n , t h e glasses are very hot. T H E T E N D E N C Y T O C R Y S T A L L I Z E is determined b y a method described b y Scha1ler.l X number of small crucibles containing t h e glass under investigation a r e maintained a t a low temperature favorable t o crystallization for a definite time, a n d t h e proportion of cases in which crystallization begins is taken as a measure of t h e tendency of t h e glass t o devitrify. R E S I S T A N C E T O A T T A C K B Y R E A G E N T S is most accurately measured b y forming beakers of t h e glass a n d subjecting t h e m t o t h e solvent action of redistilled water on t h e steam b a t h . T h e temperature t h u s attained is about 80’ a n d t h e usual time is 48 hours. T h e solution is evaporated in a small platinum dish a n d t h e residue weighed. Nonvolatile matter in t h e water used is determined a n d allowed for. Titration of t h e alkali dissolved instead of weighing is sometimes permissible b u t should be employed only for t h e comparison of similar glasses as t h e assumption is not always warranted t h a t t h e alkali found is proportional t o t h e total a m o u n t dissolved. On t h e other hand, neither t h e alkali nor t h e total solids dissolved from t h e glass will in all cases answer as index t o t h e serviceability for t h e reason t h a t some glasses leave more opaque residue on dissolving t h a n others do. The glass which is less soluble may become more cloudy when attacked b y reagents t h a n t h a t which i s ’ m o r e soluble. For comparison in this respect we find a s t e a m digester useful with pressure a t about I O O lbs. A rapid method which has been very satisfactory consists in enclosing a short length of glass rod with I O cc. distilled water in a steel t u b e provided with screw cap a n d maintaining a t a temperature of 180’ C. for 2 hrs. T h e alkali in t h e water is t h e n t i t r a t e d . Eight or t e n of these tubes are r u n a t one time. An unexpected result when, t h e glass baking dishes were p u t into service was t h e fact t h a t baking took place more rapidly in t h e m t h a n in dishes of t h e ordinary materials.2 Investigation developed a sufficient reason for t h e phenomenon b u t t h e fact was nevertheless very surprising. Metal reflects according t o various authorities from 83 t o 99 per cent of t h e radiant
’
L O C . Lit.
2
Sullivan and Taylor, LOC.c i l .
401
heat which strikes it while glass reflects only 3 t o 14 per cent. T h a t radiation a n d not convection or conduction is t h e preponderant factor in baking was established b y t h e following experiment: T h e reflectivity of a glass baking dish was changed in p a r t from t h a t of glass t o t h a t of metal b y silvering in a t h i n film on t h e outer surface in alternate quarters. A cake was baked in it in a n ordinary kitchen oven heated b y a gas fiame. Where t h e cake h a d been protected b y t h e metal coating, t h e bottom after baking was light-colored, sticky, a n d imperfectly ,baked, while in t h e other quarters it was brown a n d well done. As t h e cake was turned out bottom up t h e quartering was plainly visible on it. CORNIXG GLASS WORKS CORNING, N Y
A RAPID METHOD FOR THE DETERMINATION OF SOLUBLE NITROCELLULOSE IN GUNCOTTON By H. C. MALLINSON Received December 21, 1915
According t o t h e British Government specifications t h e determination of soluble nitrocellulose in guncotton is conducted as follows: “Four grams of dry guncotton are shaken up with 2 0 0 cc. of ether alcohol every 15 minutes for about 6 hours and then allowed to settle. When the solution above the guncotton is clear, 75 cc. are transferred t o a small weighed flask, the solvent evaporated, and the residue dried until constant in weight, a t a temperature not exceeding 65’ C.” This method, which may be styled t h e evaporation method, is, t o say t h e least, extremely tedious; a n d what is of more importance, it is not at all accurate owing t o t h e occlusion of solvent which cannot be driven off. A s t e p in t h e right direction is t h e method used b y some analysts i n which water is added t o t h e solution before evaporating. This “indirect precipitation” method is as tedious a n d takes a little longer time t h a n t h e regular evaporation method, although t h e results are lower, denoting greater accuracy, for it is obvious t h a t if none of t h e ether alcohol-soluble matter is lost, t h e lower t h e results t h e greater t h e accuracy. It is our practice a t t h e laboratory of t h e smokeless plant of t h e American Powder Mills, t o determine solubilities b y what may be called t h e “direct precipitation” method, which is not only much quicker b u t gives more accurate results. Some comparative d a t a (percentages) on different samples show interesting results: British Specification “Indirect “Direct Sample Evaporation PrecipPrecip;, Method itation” itation No. I . . ..................... 7.30 7.20 7.00 2.. ..................... 9.30 8.56 8.40 3 ....................... 20.00 19.22 18.82 4....................... 25.05(a) 24.26 23.82 (a)Obviously the error in the evaporation method increases as the solubility rises. By applying a correction, solubilities may be found by precipitation and made to agree closely with results obtained by evaporation.
T h e following results show t h a t repeated determinations are fully as satisfactory b y t h e direct precipitation method as b y t h e other methods, t h e same sample of cotton giving: Direct Precipitation Method 26 16.84 16.84 16.88
“Indirect Precipitation” 17.20 17.66 17.36
Evaporation Method 18.08 18.16 18.10
