5 90
T H E J O l - R X A L O F I * V D U S T R I r l L AiVD E N G I N E E R I N G C H E M I S T R Y
On the other hand, Steiger found "that by a very superficial treatment with hydrochloric acid approximately one-third of t h e potassium may be extracted."' I n t h e study of t h e alteration of soil minerals in this Bureau one of t h e procedures adopted has been t h e subjection of t h e finely ground mineral t o t h e action of solutions of salts, either those known to be present in soils or commonly added t o soils in fertilizers. I n t h e course of this work t h e behavior of finely ground muscovite when treated with a solution of ammonium sulfate was such t h a t while preliminary work only has as yet been done t h e results seem worthy of record. Selected laminae of muscovite f r o m a large sample of this mineral were ground in a n agate mortar t o pass a sieve 1 3 0 meshes t o t h e inch. This material in varying quantities was subjected t o t h e action of I O cc. of a solution of ammonium sulfate varying in concentration from 0 . j t o 1.5 per cent. The insoluble material was removed by filtration a n d t h e total potassium in t h e solution was determined b y t h e official method for potash in mixed fertilizers. The total potassium in t h e original muscovite was determined b y t h e J. Lawrence Smith method. The results are shown in t h e accompanying table. T h e length of time of contact of t h e solution with t h e muscovite was in all cases 24 hours; I O cc. of t h e ammonium sulfate solution were used in each experiment. The results obtained with orthoclase b y t h e same treatment are also shown. I n additions t o these tests, t w o portions of 0.5 g. of muscovite were heated in a n autoclave for I hr. a t 160' C., in one case with water only, a n d in t h e other with 2 5 cc. of a 4 per cent solution of ammonium sulfate. I n t h e case of water 4.32 per cent of t h e total potassium as KtO was rendered soluble, and in t h e case of t h e ammonium sulfate treatment 47.3 per cent. I n t h e first three tests, where t h e concentration of the 1
I
U. S. Geol. Survey, Part I, Bull 600, 236.
Vol. 9, No. 6
(NHcM0.r SoluPer PER CENT tion Approx . cent Kz0 EXTRACTBD wt. Per Temp. Kr0 in -On Basis ofNO. used, G . cent O o C. Mineral Mineral Total KnO I . . . . . . . .. . . . . 0.15 0.5 20 8.40 1.68 20.00 2 . . . . . . . .. . . . . 0.15 1.0 20 8.40 1.67 19.98 3 . . . . . . . .. . . . . 0 . 1 5 1.5 20 8.40 1.87 22.26 4 . . . . . . . .. . . . . 0.15 1.0 40 2.20 34.00 6.47 1.0 40 5 ........ . . . . . 0 . 1 5 6.47 2.20 34.00 6. . . . . . . .. . . . . 0 . 1 5 1.0 40 6.47 3.73 57.65 7 . . . . . . . .. . . . . 0 . 2 0 1.0 40 6.47 1.55 23.96 8 . ....... . . . . . 0 . 4 0 1.0 40 6.47 1.75 27.05 1.0 40 9 . . . . . . . .. . . . . 0 . 6 0 6.47 1.65 25.50 10. ....... . . . . . 0.15 1.5 40 6.47 1.87 28.90 1 1 . . . . . . . .. . . . . 0 . 1 5 1.5 65 2.07 6.47 21.98 1 2 . . . . . . . .. . . . . 0.15 1.5 2.33 80 6.47 36.01 13. ....... . . . . . 0 . 2 0 1.5 80 2.95 6.47 45.60 14 ..... 0 . 4 0 1 . 5 80 6 . 4 7 2 . 8 0 43.28 15.. ........... 0.60 1.5 80 6.47 2.33 36.01 ... 1 ............. 0 . 2 0 1.5 65 7.78 0.25 3.23 2 ............. 0 . 4 0 1.5 65 7.78 0.13 1.68 3 ............. 0 . 6 0 1.5 65 7.78 0.08 1.03
MINER4 L Muscovite
........
..
ammonium sulfate was increased while t h e quantity of muscovite and temperature remained constant, t h e differences in K 2 0 extracted were slight with n o straight increase with increase of concentration of ammonium sulfate. I n Nos. 4, j, a n d 6, where t h e conditions were approximately t h e same, there was absolute agreement between Nos. 4 a n d 5, with No. 6 very much higher. I n t h e case of Nos. 7, 8, 9 a n d IO, with t h e quantity of muscovite variable a n d other conditions constant, t h e differences in quantity of K 2 0 extracted are not significant in view of t h e variation noted where t h e quantity of muscovite was constant. The remaining tests, while suggestive of increased extraction a t higher temperatures, are suggestive only. Throughout this work t h e temperature control was approximate only a n d i t would appear from t h e results t h a t other factors are operative a n d not sufficiently controlled. The only conclusion t h a t stands out clearly is t h a t a t temperatures above 20' C. (room temperature) more K 2 0 is extracted b y this treatment. So far no results have been obtained throwing a n y light on t h e chemical changes involved or t h e process by which t h e potassium is rendered soluble. DIVISION OF CHEMICAL INVESTIGATIONS BUREAU O F SOILS, W A S H I X G T O N , D. c.
1
LABORATORY AND PLANT NEW ALLOYS TO REPLACE PLATINUM By F. A. FARRENWALD Received May 1 1 . 1917
The development of materials t o take t h e place of platinum in many of its applications has become not so much a matter of economic desire, as one of actual necessity. T h e present phenomenal activities in chemical research a n d manufacturing enterprises have resulted in a continually increasing consumption of this material, while statistics show t h a t t h e world's production has been on t h e decline. At t h e present time a n actual scarcity of metal is a matter of greater importance t h a n its consequent high cost. PRODUCTION-The following figures taken from a report by t h e United States Geological Survey, "Platinum a n d Allied Metals in 191j," give estimates of production i n troy ounces during t h e period from 1912 t o 1915,for t h e principal mining countries of t h e world.
COUNTRY
Borneo and Sumatra.. ............
.........................
Canada Colombia ....................... New South Wales and Tasmania.. Russia .......................... United States..
.
..................
1912 200 30 12,000 778 300,000 721
1913 1914 2,000 50 30 15,000 17,500 1,275 1,248 250,000 241,200 483 570
...
1915
.. 100 18,000 303 12,400 742
During 1914,t h e United States imported platinum t o t h e extent of about j 5 , o o o troy ounces, and in 1915 about 65,000 ounces. A n additional 65,000 ounces of new metal were recovered b y refiners of gold bullion and blister copper, while about 40,000 ounces of metal were derived from refining of various forms of scrap, chiefly from jewelry and dental work. MARKET-The price of platinum throughout a period of years has shown a steady increase, and there seems small likelihood of a near future return t o greatly lowered quotations. The following figures give average prices per t r o y ounce for platinum ingots a t various times since 1874.
June, 191 7
T H E J O U R N d L O F I i V D C S T R I d L d N D E N G I N E E RI N G C H E M I S T R Y
1874 $ 6.12 1888 $ 8.19
1898 $17.88 1900 $19.41
1906 $27.00 1907 $28.00
1913 1914
$ 44.88
1890 $ 8.67 1893 $ 9.19 1895 $10.22
1901 $19.93 1902 $20.94 1905 $21.45
1910 $32.70 1911 $43.12 1912 $45.55
1915
1 $ 8l050
3 45.06
( ' 49'63
19161
$ 85.50
1917i
$lli?OO
nsEs-Platinum is employed chiefly in four general fields, viz., Chemical, Electrical, Dental a n d Jewelry. A relatively large amount of this metal is actually consumed in chemical applications, as in electrolytic processes, b u t a large p a r t of it, as in t h e form of crucibles, dishes, a n d other apparatus, is not destroyed, a n d with care may be used indefinitely. I n t h e electrical field platinum finds a variety of uses, chiefly, however, in t h e form of contact points on ignition a n d lighting systems, and in a similar form on numerous types of automatic electric apparatus from automatic telephones and signalling devices t o t h e ordinary every-day temperature-controlled electric iron or heating pad. h o s t of t h e metal used in this manner is destroyed. Large quantities of plati n u m are also used in t h e construction of electric resistance furnaces for high-temperature work. as in experimental laboratories. The material in this application is not, however, destroyed a n d may be refined a n d used again. Perhaps t h e greatest actual consumption of platinum occurs in dentistry. It is employed here as pins in artificial teeth, and as foil, plate a n d sheet in other forms of dental construction. I t is estimated t h a t about one-third of t h e entire consumption of platinum may be accounted for in this manner. As yet no means have been devised t o prevent this noble metal from being lost forever. Perhaps actual necessity may yet become sufficiently pressing t o overcome false sentiment, which no doubt a t this time would greet with horror a suggestion t h a t all teeth or other devices containing platinum be removed from t h e remains of those for whom i t had completed its time of service, a n d so be made available for further duty. T h e jewelry industry is without doubt t h e greatest offender, and proper steps should be taken a t once t o prevent t h e use of platinum in this field. It is not economically sound t o permit mere foibles of fancy or dictates of fashion t o remove from service a material which is absolutely necessary in t h e sciences a n d industries. It is estimated t h a t t h e jewelry industry consumes nearly one-third of t h e entire production of platinum, a n d while some of this is recoverable. most of it, when once in private ownership. is practically lost. I n many instances where formerly it was thought t h a t only platinum could be used, alloys have been developed which, for a given well defined purpose, are quite as satisfactory: in chemistry, laboratory ware of fused quartz, larger apparatus of t h e various highsilicon iron alloys, nickel chromium alloys and other materials have been adapted to specific phases of t h e industry, where hitherto only platinum had been found satisfactory. I n t h e electrical field, platinum for resistance heating elements has been largely replaced by alloys of nickel a n d chromium. For electrical contact material!
591
as in many forms of ignition and automatic electric devices, platinum has been, t o a certain extent, replaced by tungsten. Most of t h e manufacturers, however, of high-grade magnetos a n d other apparatus demanding high-duty service, still think i t necessary t o use platinum as t h e material of contact terminals, although in t h e majority of cases t h e alloys described herein are satisfactory. Platinum is no longer used extensively in t h e manufacture of incandescent lamps, having been replaced b y a copper coated, nickel-iron alloy which has t h e same coefficient of expansion as platinum. Many forms of substitution are practiced in dentistry t o avoid t h e use of platinum. T'arious forms of German silver, gold alloys, and others, are used with varying degrees of satisfaction, b u t there are many applications in which no other heretofore available material will serve. The writer has developed a method of coating tungsten or molybdenum with precious metals which gives a material of even greater strength and permanence. For t h e manufacture of jewelry no other metal or alloy combining t h e qualifications of workability, appearance, permanence a n d intrinsic value, has been available. I t is thus evident t h a t while other materials have been developed t o successfully replace platinum in a few specific instances, researches have not heretofore produced a material which in all of its characteristics and properties can serve as a general purpose substitute. I n considering a material t o replace platinum i t is necessary t o regard as criteria those properties which make it valuable in applications where no other metal will serve. I t s value industrially is chiefly due t o a high melting point, and chemical inactivity under those conditions which exist in its application. It is also very malleable a n d ductile. a n d may readily be worked into t h e great variety of intricate forms so often required. I t is apparent, then, t h a t a proper substitute must satisfy t h e following conditions: SPECIFICATIOSS FOR A SUBSTITUTE
I-Its melting point must be high. For chemical purposes a material t h a t would fuse a t t h e temperat u r e of t h e ordinary gas flame would find limited application. I n electrical uses high fusing point is one of t h e chief requirements, while in dental manufacture, platinum is subjected t o temperatures which are seldom below 1 2 5 0 ' C . , so t h a t about 1300 t o 1400' C. would be a fair minimum temperature t h a t a satisfactory substitute must withstand. 2-It must not be affected by mineral acids, or alkalies, either fused or in solution, and must not oxidize a t a n y temperature up t o and including t h a t at its melting point. 3-It must be malleable and ductile, and sufficiently strong t o withstand stresses tending t o change its form while in use. 4-The chief requirements for jewelry purposes would seem t o be rarity and high cost, although the above criteria t o a certain extent govern its use in this
592
T H E J O C R N A L OF I N D U S T R I A L A S D E-YGISEERISG CHEMISTRY
field also. I t is doubtful whether color or appearance are of greater importance t h a n intrinsic value but in order t o substitute for platinum in a strict sense, a platinum-white color is desired. One phase of researches conducted in t h e x-riter’s laboratories during t h e past several years has dealt with t h e development of alloys’ t o replace platinum, and aside from t h e treatment of special applications, attention has been given t o a consideration of t h e possibilities of producing a material which should practically duplicate platinum in its general characteristics a n d behavior when judged according t o t h e above set of requirements. This work has resulted in a material which in most of its general chemical a n d physical properties is almost indistinguishable from platinum itself, as may be seen f r o m t h e hereinafter described results. DISCUSSIOK O F POSSIBILITIES
I t is theoretically indicated, and has been experimentally proved t o t h e satisfaction of t h e writer, t h a t no other possible combination o j elements can result i n alloys of equally enhanced properties, when judged with platinum a s the criterion. I n order t o develop this thesis, a n d in so doing eliminate fruitless fields for further research, i t will be necessary before describing these resulting alloys, t o consider briefly a few factors involved in their development. The production of alloys of special properties is no longer a matter of “discovery.” I n t h e days of t h e alchemist men p u t forth every effort in vain attempts t o produce gold artificially, a n d sought b y t h e use of a philosopher’s stone t o transmute base metals into a more noble form. At t h e present time, however, when molecules, atoms, and electrons are a matter of fruitful study, t h e hope of actually changing one element into another is not so fanciful. But in t h e meantime, advances can be made only by properly combining t h e simple elements t o form alloys having properties superior t o those of t h e component metals. The s t u d y of metals, as a n exact science, is of comparatively recent origin, although some of t h e devices of metallurgy have been unconsciously employed b y men for ages. The first advances in t h e art of treating metals t o improve certain of their properties were no doubt a matter of accidental discovery. as when some warrior discovered t h a t t h e metal of his spear and arrowheads could be hardened b y hammering between t w o stones. Even though accidental, a n invention of this nature advanced his tribe, more, perhaps, t h a n did t h e discovery of t h e metal itself. The forger of t h e Damascus blade did not know t h e inner nature of his secret process, b u t this d d not detract from t h e prowess of its wielder. So, t o t h e present day, m a n ‘ s advance has been suggestively paralleled b y his increasing knowledge of t h e properties of t h e metals. With knowledge of t h e elements came t h e discovery t h a t certain combinations of metals possessed properties far more valuable Descriptions of these alloys are also 1 See Bull. A . I . M . E. Jan,, 1916. subject-matter of professional reports made in 1913.
v01. 9. NO. 6
t h a n those of any single one, and t h e continued pursuit of this study has produced materials which have revolutionized industry and warfare. It has produced tools for mining and agriculture; i t has made possible steam vessels and railroads, a n d has permitted t h e present great diffusion of thought a n d knowledge by means of t h e printing press, photographic appliance, telegraph, cable a n d telephone. -4s t h e results of these early researches radically changed many phases of industry, so in t u r n , the present changing industrial and economic conditions demand further applications of science in order t h a t new conditions may be properly met as t h e y develop. I n alloys of iron a great number of special steels have been developed which meet a n y reasonable specifications in t h a t field. I n a like manner t h e alloys of copper, zinc, tin, nickel a n d other metals have provided a series of brasses a n d bronzes of remarkable perfection. Similar successes have not attended efforts t o replace t h e precious metals, a n d especially is this true of platinum. I n undertaking t h e solution of this problem, i t was found, after t h e entire list of metals h a d been considered with t h e above imposed conditions a s criteria, t h a t no element, aside from platinum, would satisfactorily meet t h e above outlined specifications. I n view of t h e fact t h a t no single metal was available for this purpose, i t was evident t h a t a n y search for t h e desired material must be among alloys, for experience has shown t h a t t h e properties of a metal may b e radically changed b y t h e addition t o i t of varying amounts of another element, or of several elements, as in t h e case of steels, brasses, a n d bronzes. A review of t h e literature reveals nothing of direct bearing on this question. The same underlying principles, however, are involved in all investigations of this nature, so advantage may be taken of t h e broad generalizations which have resulted from t h e numerous researches on other alloys. Considerable work i n t h e line of thermal analysis has been reported which covers many of t h e metals under consideration, a n d in these resulting diagrams of thermal equilibrium t h e proportion a n d type of t h e different constituents of a series of alloys may be easily detected. It is known t h a t t h e relation between t h e constitution of a n alloy and its various properties is rather well defined, so, t o a certain extent, it is possible, from a study of a given equilibrium diagram, t o interpret in terms of characteristic properties, t h e terms given a s constituents. I n view of t h e fact, then, t h a t t h e general properties of a n alloy are dependent upon t h e t y p e of its constituents, a n d t h a t these in t u r n are dependent upon t h e nature of their components (the elements) i t is desirable t h a t certain applicable laws be briefly pointed out, a n d t h a t t h e inter-relationship of t h e elements themselves be taken into consideration, for without this information it would not be possible t o select, f r o m t h e entire list of t h e elements, those which might properly be included in a n investigation of this nature. The relationship of t h e elements is best revealed by some form of t h e periodic table, as conceived first
T H E JOLTRNAL 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 V I S T R Y
June, 1917
by Sewlands a n d later improved a n d enlarged by Lothar l l e y e r and Llendel6eff. Werner’s rearrangement of this table is, perhaps, t h e most satisfactory for purposes of alloy comparison. The accompanying table was constructed in this manner. omitting. however, t h e rare elements not of interest in this connection, a n d so allowing a better comparison of t h e metallic elements t h a n does t h e complete chemical table. If one begins a t t h e upper left-hand corner and rends bookwise. i t is found1 t h a t t h e atomic weights show a n almost uniform increase from Hydrogen I t o Thorium 232.j. The horizontal rows represent groups, each containing seventeen elements arranged i n two series of seven, each, with a “transition” series of three elements; t h a t is, I t o 7 constituting one series, I U to ? a t h e second series, a n d 8 t h e intermediate or transition series. I n t h e ordinary chemical table t h e elements are arranged according t o valencies,
I
1 i J - 3 4 H (ELEMENT) 1.008(ATOMICWEIGHT)
5
6
593
with markedly acid-forming elements; e. g., zinc, in I U , a n d bromine, in 7a, of t h e same group. The elements (8) connecting these series are intermediate in their behavior between t h e elements on either side, those of t h e first vertical column (iron, ruthenium, osmium) forming both bases a n d acids; t h e others only acids. I n passing, with consecutive readings, from one horizontal group t o t h e next lower, however, one notes a sudden change in t h e chemical properties of elements of consecutive atomic weights. Thus, t h e last element of Group 11, fluorine, with a n atomic weight of 19, is in complete contrast. in its chemical nature. to t h e next element sodium. with a n atomic weight of 23.5) and which belongs in Group 111. Iodine, the last member of Group 111, forms powerful acids while cesium, t h e first member of Group IV, is one of t h e most powerful base-forming elements known. If t h e elements in a vertical column are considered
Za 3a 4a 5a 64 7a
7
-258? LflELTING PO\NT)
Li
1 7.03
Be
0
c
9.1
11.0
\2.0
18G.0 900 !’ R O O ? ? Na llg AS. 5i 31.0 32.06 35.45
C):f
44
-102
,
Ge 12.5 1520 -
900 -
Ru
3n 118.5 e32
109.17
2000 -I os
Hg TL Pb Bi F00.3 Z04.1 207.1 208 -39 1302 l327.01 iz70
1
I
I
I
225
232.5
?
l700?
PERIODIG ARRRNGEMENT
I
PI: I
OF G O M M O N ELEMENTS
which brings t h e elements of Column I and I U , 2 and za, etc., together, with considerable coniusion as t o their physical a n d chemical properties. I n t h e present table t h e common elements are shown arranged in accordance with their atomic weights, t h e group designations I , I U , 2 , 2 u , etc., being retained merely as a n assistance t o those familiar with t h e usual chemical table. Within any one group there is no sudden change in properties when passing from one element t o t h e next in order. Considering t h e two series forming one group, t h e first begins with elements which are strongly base-forming, a n d ends with strongly acid-forming elements; e . g., potassium, of Column I , and manganese, of Column 7 . The second series begins with elements which are only moderately base-forming and ends 1 These simple relationships are of course, well known. I t is thought well, however, briefly to review them in order t o draw more clearly a parallelism in the case of alloying characteristics, which is not so commonly recognized.
i t is found t h a t they are, on t h e whole. such as would naturally fall together in a classification of t h e elements according t o their general chemical and physical properties. Thus, in t h e first column are lithium, sodium, potassium, and cesium-the metals of t h e alkalies; in t h e second column are calcium. barium, and strontium-metals of the alkali earths, and so on. Space is not available for a detailed discussion of many other relationships which have been found t o exist, b u t i t is apparent t h a t t h e elements of a vertical column are very similar, and t h a t there is no radical difference in t h e general properties of horizontally adjacent elements. It is evident, therefore, t h a t a similarity of properties exists among t h e elements occurring in a n y one part of t h e table. a n d t h a t t h e general properties of a n element can be foretold from its position on t h e periodic table. The melting points, for instance, which have been included for comparison in this table, range from low t o high, or from high t o
594
T H E J O U R N A L OF I N D U S T R I A L AhrD E Y G I N E E R I N G C H E M I S T R Y
low, in a n y given column, a n d in reading through a n y one group t h e successive figures do not represent very great contrasts. This same relationship governs all other properties as, for instance, malleability a n d ductility. Considering Column I a , as a n example, copper is very easily rolled, drawn, or otherwise manipulated; silver, t h e next lower, is more so, while gold, a t t h e bottom, is t h e most malleable of known metals. If one metal, therefore, possesses special properties which make it valuable for given industrial purposes, i t is reasonable t o suppose t h a t those metals which occupy adjacent positions on t h e periodic table may possess these same properties t o some extent a t least, a n d would, therefore, bear investigation-especially if they come within t h e same vertical column. There i s no difference betzleen reactions zehich take place at very high temperatures, resulting in the f o r m a t i o n of alloys, and those which take place u n d e r ordinar31 conditions. A l l reactions and conditions of e q u i l i b r i u m are governed by the s a m e rules, and corresponding constituents result i n all cases. It is evident, then, t h a t the general l a w s and relationships governing the alloying behavior of the metals are the same as those which have been f o u n d t o exist in the case of o r d i n a r y chemical reactions. When two or more metals are brought together in t h e liquid state: t h e conditions existing are similar t o those found if two or more ordinary liquids are mixed. When t h e temperature is sufficiently lowered t h e solidified mass may contain a n y one of t h e four folloiving constituents: pure components, solid solutions, compounds, or eutectics, or some combination of these. A comparison of t h e properties of different alloys containing these constituents has shown t h a t they impart their characteristic properties t o t h e alloy of which they form a p a r t ; in fact, t h e relation between the constitution of a n alloy a n d i t s properties i s so clearly defined that the possibilities 0.f i n d u s t r i a l application m a y be predicted f o r a given alloy, i f i t s constituents are definitely known. Conversely, if a certain applicat i o n i s desired, a s in the problem u n d e r consideration, a definite l i m i t m a y be placed u p o n the n u m b e r a n d a m o u n t of constituents permissible. Fortunately, t h e number of constituents is limited t o four as given above. Pure metals impart their own characteristics; solid solutions are, in general, t h e ductile constituents (if formed from ductile metals, or of a preponderance of one ductile metal); compounds are hard a n d brittle; while eutectics are usually brittle and hard, a n d even when present in very small amounts. tend t o solidify between t h e grains of t h e alloy and destroy its ductility. Thus another requirement may be added; a substit u t e for platinum must be a homogeneous solid-solution alloy. This brief discussion has, in a very general manner, outlined t h e inter-relationship of t h e elements when arranged in t h e periodic order of their properties, a n d has pointed out t h e similarity of properties of elements grouped in a n y part of t h e table. The general properties of a n alloy have been shown t o depend upon its constituents, a n d these constituents in t u r n have been
Vol. 9 , No. 6
briefly discussed with reference to their characteristic physical properties and with reference t o t h e probability of t h e occurrence of similar constituents in alloys of closely related elements. It is not safe, however, t o generalize in too broad a manner upon any assumed relationship between certain elements, b u t i t would be impossible t o make a logical search for any special alloy, in a field containing all of t h e elements, without first having definitely outlined t h e mutual relationship and behavior of t h e component elements. With t h e elements arranged in this manner i t becomes a t once evident t h a t characteristic chemical or physical properties are confined t o definite limited areas of t h e periodic table. The properties characteristic of silver, for instance, are more or less common also t o those eight elements contained in squares surrounding i t ; this is especially t r u e in t h e case of those of t h e same vertical column. I n this manner a n y element on this chart may be analyzed a n d all other elements contained in non-adjacent spaces will be found markedly dissimilar t o i t in chemical behavior a n d in general physical properties. Considering platinum in this manner, i t is at once evident t h a t its general properties will be found i n no metal other t h a n those adjacent t o it. These surrounding elements are iridium, rhodium, palladium, silver a n d gold. All metals outside of this block are affected b y common reagents a n d gases, and, without exception, are not stable a t elevated temperatures in normal atmospheres. Considering each of these in t u r n , however, i t is found t h a t not one is suited as a general substitute for platinum. Iridium a n d rhodium are very refractory; they cannot be readily worked, a n d are so rare a n d expensive as not t o be economically permissible. Palladium, while meeting most physical requirements, is readily oxidized or carbonized, a n d is quite soluble in several of t h e common acids, especially nitric. Silver is readily attacked b y acids, and is of too low melting point t o serve, except in special cases. Gold resembles platinum in more respects t h a n does any other metal. It is, however, not sufficiently refractory a n d is too soft t o find wide application industrially. A metal falling below plati n u m in t h e same vertical column would be possessed of properties still more enhanced, for t h e “nobility” of t h e elements of this column becomes greater with increasing atomic weight. The above consideration is not merely theoretical, for experimental work involving most of t h e promising metals outside of t h e above list has supported this view. Having limited t h e possibilities t o t h e rather confined area indicated, it was necessary t o combine these included metals in such manner as t o eliminate or neutralize undesirable features, and t o develop those properties which were necessary. The material of chemical ware must not contain silver because of its affinity for many of t h e reagents commonly employed. The use of rhodium a n d iridium in large proportions is obviously not practical, SO t h a t
T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
June, 1917
TABLE I-TESTS
595
ON SAMPLES OF RHOTANIUM (Submitted by F. A. Fahrenwald)
Each test piece was about 0.1 mm. thick and presented 10 square centimeters of surface. The palladium was electrolytic metal from Baker and Company. The gold was U.S. mint gold, 0.999 fine. The platinum was t h e pure foil of commerce. ACTION O F HYDROCHLORIC ACID
ACTION OF F U S E D S O D I U M H Y D R O X I D E
The pieces were boiled in the concentrated acid for 3 hours and showed losses in weight as follows: 5 0.05 mg. CONCLUSION: Hydrochloric acid is pracA 0.05 tically without action. A5 0.05
The pieces were immersed in the fused hydroxide in a nickel crucible and kept for 2 hours a t a low red heat. They showed the following losses: 5 4.45 mg. CONCLUSION: Alloys high in gold are more reA 4.95 sistant, but all are somewhat attacked. It is well B 4.00 known t h a t platinum is badly attacked. D 9 . 2.5 Pd 18.45 Au 7.95
ACTION O F HYDROFLUORIC ACID
The pieces were boiled in the concentrated acid for 3 hours and showed the following losses in weight: 5 0.0 CONCLUSION: Hydrofluoric acid is entirely without action. A .45
B
C
D Pd Au Pt
0.0 0.0 0.0
0.05 0.0
0.11 0.05 0.0 A C T I O S O F CONCENTRATED NITRIC ACID
,
The pieces were boiled with the concentrated acid for 3 hours and showed the following losses in weight: 5 2.85 mg. CONCLUSION: Hot, concentrated nitric acid A 2.15 attacks all the alloys very appreciably, AS 2.25 especially those very high iri gold. B 2.15 c 2.15 D 2.30 Au 3.25 Pd Much attacked Pt 0.05 ACTION OF D I L U T E N I T R I C ACID
The pieces were boiled with the dilute acid, one part of nitric to two of water, for 51jz hours; the solution concentrating to a ratio of one acid to one water. The following losses in weight occurred: 5 0 . 1 mg. CONCLUSION: Hot, dilute nitric acid is practically A 0.05 without action in all cases. 0.05 A5 B 0.05
c
D Au Pt
A C T I O S OF F U S E D SODIUM C A R B O N A T E
The pieces were immersed in the fused carbonate in a nickel crucible and kept for 2 hours a t a bright red heat. They all showed slight gains, when there was any change. They were bright and showed no evidence of corrosion. I t is difficult to explain the gain in weight. except in the case of Pd, which was undoubtedly somewhat oxidized. 5 Too soft, tended to stick t o crucible A 0 . 0 mg. A5 0 . 5 5 mg. gain CONCLUSION: The alloys are not apB 0.25 gatn preciably attacked by fused NazC03 and C 0.25? gatn are equal to platinum in this respect. D 0.25 gain Au Stuck to the crucible Pd 3.05 gain Pt 0.80
ACTION OF SODIUM S U L F I D E SOLUTION
The pieces were boiled for 3 hours in a solution of sodium sulfide containing a little polysulfide, and saturated a t room temperature. 5 0 . 0 mg. P d 0 . 7 5 mg. loss CONCLUSION: The Pd A 0.05 mg. gain Au 0.45 mg. loss was somewhat tarPt 0.0 AS 0.0 nished; the others were B 0.1 gain erfectly bright. he alloys are not all c o>1 ga!n D 0.05 gain attacked by concentrated hot sodium sulfide solution.
+?
0.05 0.05 0.05
0.0
ACTION OF AMMONIA ACYION O F C O N C E N T R A T E D S U L F U R I C ACID
The pieces were boiled with the concentrated acid for 5'/z hours and showed the following losses in weight: 5 0.05 mg. CONCLUSION: Hot, concentrated sulfuric A 0.05 acid attacks the alloys high in gold very A5 0 . 1 5 . . . 0 . 4 0 mg.* slightly, the rate of solution increasing with the proportion of palladium. All the B 0.20 alloys are superior t o platinum in this test. c 0.50 D 1.60? Au 0 . 0 5 . . . . 0.35 me.* Pd Rapidly attackedPt 2.00 After 14 hrs. a t 300' C.
.
The pieces were boiled 5 hours in a concentrated ammonia solution. 5 0.0 mg. CONCLUSION: The alloys are not in the least A 0.0 attacked by hot, concentrated ammonia A5 0.05 gain solution. B 0.05 loss
c
0.0
D Au Pt
0.0 0.0
0.io
loss loss
~~~
*
ACTION A S CATHODE I N ELECTROLYTIC DEPOSITION ACTION O F F U S E D P O T A S S I U M B I S U L F A T E
The pieces were all immersed together in potassium bisulfate kept a t a very low red heat in a porcelain crucible for two hours and showed the following losses: 5 0.65 mg. gain Had a silvery appearance showing probable A 0.25 mg. loss deposition of Pd on its surface. AS 0.40 loss B 5.00 loss C 16.85 loss D 49.4 loss Au 0 . 6 0 mg. gain Had silvery appearance, showing t h a t Pd Very rapidly attacked P d had probably been deposited upon Pt 0.25 it. CONCLUSIONS: T h e action is similar to t h a t of concentrated sulfuric acid but more intense. It is probable t h a t alloy 5 and Au were slightly attacked, b u t the P d taken up more than compensated for the loss. Alloys high in gold are equal to, or better than, platinum. ACTION O F S O D I U M H Y D R O X I D E I N S O L U T I O N
The pieces were boiled with 40 per cent sodium hydroxide solution for 3 hours, and showed the following losses: 5 0.0 CONCLUSION: Hot, concentrated sodium hydroxide soluA 0.0 tion is entirely without action. AS 0.0 B 0.0 c 0.0 D 0.05 Au 0.10 Pt 0.0
The pieces were plated with copper in a solution containing nitric and sulfuric acid, and the deposit was dissolved off by a brief treatment with warm dilute nitric acid, one to one. The losses were: 5 0 . 0 mg. CONCLUSION: The alloys are satisfactory as cathodes A 0.1 in the electrolytic determination of metals. A5 0.05 B 0.1 c 0.1 D 0.0 .4u 0.05 Pt 0.0
ACTIOX A S A N O D E I N S U L F U R I C ACID S O L U T I O N
The pieces were made the anode in a hot solution of dilute sulfuric acid, one acid to eight water, for 10 minutes using 10 amperes of current. The losses were: 5 2 6 . 5 mg. CONCLUSION: The alloys are all worthless for use as A 37.6 anodes in electrolysis in acid solutions. A5 39.1 B 37.6 C 29.0 D 33.8 Au 48.0 Pt 0.1 (Signed) H. H. WILLARD University of Michigan
596
T H E J O U R N A L OF IiYDCSTRIAL A N D ENGINEERING C H E M I S T R Y
finally only gold a n d palladium remain as t h e permissible chief components. of a n alloy which should more nearly duplicate t h e general properties of platinum t h a n could a n y other metal or combination of metals. A detailed investigation of alloys of these metals has resulted in materials' which for many practical purposes cannot be distinguished from platinum. E X P E RI M E A- T A L
The following results of final tests made t o determine t h e behavior of these alloys under practical conditions of operation were carried out on specimens 0.10mm. thick a n d of such size as t o present exactly I O sq. cm. of surface. Earlier work revealed t h e fact t h a t in order t o produce t h e desired results, i t was necessary t o make use of small percentages of rhodium; this is not necessary in t h e case of material for chemical ware; for certain electrical and other uses, however, i t is quite essential. It is also permissible t o use limited percentages of silver in some of these non-chemical applications. It is necessary t o observe every precaution in t h e preparation of these alloys, because of t h e affinity of palladium for many gases and solids ordinarily enTABLE11-Loss Boiling Boiling Conc. Conc. Alloy h-0. HCl HF . . . . . . . . . . . . . . . . 5 0.166 0.0 X . . . . . . . . . . . . . . .0 166 0.0 As... 0.166 0.0 B . . ............. 0.0 0.0 c . . . . . . . . . . . . . . .0.0 0.0 D . . . . . . . . . . . . . . .0 . 0 0.0 Pure A u . . , , , , , .. 0 , 1 6 6 0.166
............
Pure P d . . . . . . . . . 8.0
0.33
Pure Pt . . . . . . . . . . 0 . 0
0.0
Vol. 9, No. 6
t h a n t h a t of platinum. This is especially t r u e in t h e case of concentrated boiling sulfuric acid. VOLATILITY AT HIGH TEMPERATURES
I n determining losses b y volatilization a t high temperatures, test specimens taken f r o m t h e same ingot a n d duplicating those described above were employed. These were heated in a gas muffle furnace using natural gas a n d compressed air. These experiments were run in triplicate in two series: first in t h e muffle with free access t o air, but with t h e products of combustion excluded; a n d second, heated directly in t h e gases of combustion with free air excluded. N o difference in results was observed under these two sets of conditions. The comparative test pieces of palladium were of vacuum-fused electrolytic metal, while t h e test-specimens of platinum were cut from a new Baker crucible. I n these experiments t h e muffle was brought t o t h e desired temperature a n d t h e test samples allowed t o remain therein for one hour before cooling a n d weighing preliminary t o t h e test run. An assay balance, reading directly t o t h e fifth place, was used in determining t h e weight of each specimen before a n d after treating. Each experiment consisted in a continuous Io-hour
MILLICRAXS PER HOURPER 100 SQUARECENTIMETERS (SUMMARY O F TABLEI) Boiling Boiling Boiling Fused Boiling Fused Fused Conc. Dil. 1 to 2 Conc. (Red heat) 40% Sol. (Red heat) 1000° C. "03 "01 HzSOd KHSOi NaOH NaOH XazCOs 9.5 0.2 0.1 0.0 0.0 22.2 0.0 7.5 0.0 0.0 0.1 1.2 0.0 24.7 7.0 0.0 0.3 2.0 0.0 +2.7 7.0 0.0 0.4 25.0 0.0 20.0 +1.2 7.0 0.0 1.0 84.0 0.0 ..... +6.2? 7.0 0.0 3.0 297.0 0.0 1967 +1.2 10.8 0.0 0.1 0.0 0.3 39.; ....
IN
.....
Boiling Sat. Sol. NazS S 0.0 0.0 0.0 0.0 0.0 0.0 +l.S
+
Boiling Conc. NHdOH 0.0 0.0
0.0 0.0 0.0 0.0 0.0
V*F"
Rapidly Attacked 0.166
Rapidly Attacked 0.0
Rapidly Attacked 4.0
countered in t h e process of manufacture. The most careful heat-treatment also is necessary t o insure freedom from segregation. T h e slightest inhomogeneity is fatal t o uniformity of results in practically e r e r y application-especially for chemical purposes. Losses in acid solution, for instance, for different test-specimens made from t h e same alloy ingot, have been found t o vary b y over 1000 per cent. Properly prepared material, however, gives absolute uniformity of results. CHEMICAL PROPERTIES
Rabxly Attacked 1.45
0.0
0.0
92.0 Rapidly Attacked
f15.2 $4.0
0.0
+2.5
0.0
0.0
run, with t h e temperature maintained within * 2 j O C. of t h e figures given below. Losses a t these various temperatures, in terms of milligrams per hour, per I O O sq. cm. of surface, are given in Table 111. TABLE 111-LOSSES I N MUPPLEFURNACE Sample 1050° C. 1200" C. 1300° C. 1400' C Rhotanium No. 5 2.0 Melted Melted A 0.8 3.1 Melted ... A5 0 . 6 2.0 Melted ... B 0.4 1.4 6.0 ... c 0.4 1.3 4.0 7.1 D 0.2 0.6 2.82 5.8 Au Pd i : i (gain) 14:O (gain) 3?:0 (gain) l2O:O (gain) Pt 1.3 2.40(a) 3.1 4.5 ( a ) Burgess gives 0.71 to 2.79 mg. (Bureau of Standards, Scientific Paper No. 254).
.
...
On page 59j is shown a test-certificate from t h e University of Michigan Chemical Laboratories which gives results obtained from a series of Rhotanium alloys, together with figures for gold, palladium a n d platinum for comparison. When tabulated in terms of loss in milligrams per hour per r o o sq. cm., t h e results appear as in Table 11. It is seen from these figures t h a t for ordinary use with a n y of t h e above named reagents, excepting concentrated nitric acid. a n alloy may be chosen of a composition t h a t will give service equal t o or better
After heating for I O hours a t these temperatures t h e surface of each specimen (melted a n d otherwise) was perfectly bright. At 1400' C. t h e crystalline structure was clearly shown, due t o selective volatilization or grain growth, b u t no brittleness was produced. The gain in case of pure palladium is due, no doubt, . t o oxidation, although palladium also carbonizes very easily.
The name "Rhotanium" has been applied to this series of alloys. Alloys of different composition for distinct purposes are distinguished by sub-letters as shown in the various tables of properties. This name has been registered, and all alloys, both as to composition and use, are covered by patent applications.
The alloys As, B, C and D are practically white. C and D especially can only with difficulty be distinguished in appearance from platinum, a n d then only when in t h e form of sheet. Wires or articles of
1
PHYSICAL PROPERTIES
T H E J O l - K S AL OF InI‘DCSTRIAL A N D E N G I N E E R I S G C H E M I S T R Y
June, 191;
intricate design present a true platinum appearance. All are very malleable a n d ductile. and can be rolled, spun, or otherwise worked into a n y desired form. Figures for some physical properties are given in Table ITr. TABLEI\--I”YSICALPROPERTIES OF RHOTANIUM ALLOYS ’
Melting point O
ALLOY 5
A A5 B C D Au Pd Pt
C. 1150 1220 1280 1350 1410 1450 1063 1550 1775
F.
(Calc.) 2100 2228 2335 2462 2570 2642 1945 2822 3191
Sclero- Tensile Electrical scope Strength ConducHard- K g . per tivity Temperature ness sa. mm. X 10-4 Coefficient 26 ... 35 13.5 0.00097 40 10 ~. 9.8 0.00065 13 45 7.85 0.00060 16 50 5.5 0.00050 51 3.8 0.00032 21 l; 0.00326 45.5 30 9.45 11 0.00328 24 9 0.00348 9.94
4
-4s may be judged from t h e above described properties these alloys are well suited t o replace platinum in many of its applications in all fields, and have been so used for a long period with entire satisfaction. By taking advantage of t h e ease with which chemical a n d physical properties may be modified through adjustment in composition, various alloys of this series have operated fully as satisfactorily as platinum in chemistry, dentistry, jewelry. a n d i n many electrical appliances. Various grades of this material have undergone extended field trials, t h e results of which may be summarized as follows for t h e various fields of application. CHEMICAL
Rhotanium cannot substitute platinum when exposed t o t h e action of hot concentrated nitric acid, or when used as anodes in electrolytic work, b u t for all other purposes i t is entirely satisfactory ij the proper composition is chosen, a n d if f i r o p e d y manufactured. It is equal t o platinum in t h e case of hot concentrated hydrochloric or hydrofluoric; hot dilute nitric; fused potassium bisulfate; hot concentrated sodium hydroxide solution; fused sodium carbonate; hot concentrated sodium sulfide solution; and in its resistance t o oxidation a t high temperatures. It is superior t o platinum in its resistance t o t h e action of hot concentrated sulfuric acid or fused sodium hydroxide. It is satisfactory as material for cathodes in t h e electrolytic determination of metals. Losses b y volatilization a t temperatures below 1300’ C. are less t h a n for commercial platinum. Rhotanium may be rolled into sheets of a n y size, a n d may be formed either cold or white hot into any desired shape. I t welds as readily as wrought iron a t a white heat without t h e use of flux or other reagent. Due t o greater strength a n d lower specific gravity, articles of rhotanium weigh only half, or less t h a n half as much as similar articles of platinum. The specific gravity of alloys in this series varies from 18. j t o about 16.0, depending upon t h e composition: t h a t of platinum is 2 1 . j . ELECTRICAL
Rhotanium is satisfactory within its temperature limitations as t h e material of resistor elements in electric heating units. I t is not oxidized a n d is less volatile below 1300’ C. t h a n platinum. I t s high resistance and low temperature coefficient are valuable in this connection.
597
It is satisfactory as material for contact terminals in many forms of automatic-electric devices a n d may be used in this capacity on certain types of telephones, switchboards, signal devices, lighting a n d ignition systems, and in most other cases except where i t has been found necessary t o use a high percentage of iridium alloyed with t h e platinum. I t s behavior when tested on certain magnetos was satisfactory, b u t other experiments performed on a high-duty aeroplane engine magneto ga7-e negative results. DEKTAL
Certain of these alloys have been in t h e hands of operating dentists for some time a n d have proved t o be equally as good as platinum for many purposes. They have been used for pins and baked into porcelain teeth and as thin foil a n d heavy sheet for other types of construction, all with t h e most satisfactory results. 1E LVELRY
Rhotanium is superior t o pure platinum for use in jewelry. It is harder a n d stronger, a n d takes a better finish. It is absolutely not tarnishable or corrodible, and its color is practically platinum-white. It can be as readily worked as platinum, a n d scrap may be remelted for further use. It may be forged either cold or white-hot a n d may be “sweated” or otherwise treated as platinum without oxidizing or darkening in color. Finished articles of rhotanium jewelry of t h e more intricate designs can b y no ordinary means be distinguished from platinum. This material passes t h e common jeweler’s and platinum buyers’ tests a n d there will no doubt be some confusion resulting from t h e passing of this material for platinum. Exhaustive tests have shown t h a t most of t h e uses for which platinum has heretofore been considered indispensable can be filled b y one of these alloys, t h u s freeing platinum for those remaining applications where no other material can be employed. T h e extent t o which platinum may be replaced in this manner is limited b y t h e amount of palladium available, and when i t is considered t h a t these alloys contain from 90 t o 60 per cent of gold i t is evident t h a t t h e effective supply of platinum may thus be increased by many thousand ounces. 1706 GLENMOSTROAD CLEVELAND, OHIO
A PRACTICAL METHOD FOR DETERMINING THE VISCOSITY OF STARCH FOR MILL PURPOSES By G. M. MACNIDER Received March 16, 1917
Several years ago t h e author described in THIS a method for determining t h e viscosity of starch solutions for determining t h e value of different starches for cotton mill purposes. Since t h e publication of this article t h e author has had t h e opportunity of applying this method t o practical mill work a n d has worked out a modification of t h e method which is described in this paper. T h e original method is briefly as follows: 1 2 grams * THISJ O D R N A L 4 (1912), 417. JOURNAL’
