Document B8QVoeGveJ33nz7e72zR1gGZE

FILE NAME: American Cyanamid (AMCY) DATE: 1938 May DOC#: AMCY030 DOCUMENT DESCRIPTION: Journal Article by Dr. Gardner - Reaction of the Living Body to Mineral Dusts NOW 8 5 ,0 0 0 KW IN AJAX-NORTHRUP FURNACES AND HEATERS The curve on this page shows the growth in K W o f A jaxN orth ru p Furnaces installed aii over the world during the past ten years. ASSOCIATE COMPANIES The A } `M etal C. Non-ferrous logoi 'Mela! op iouftdcy use. Ajox Electric Furnace ,, Cerporotion , 'A(ox-WyeH Induction Fur naces Tor melting. Ajax Electric Co-, Inc. A)# x.H ulfgren Salt Beth Furnace and Resistance Typ E t a c tf C Furn aces for a UHoot treatm ooperations. USED FOR MELTING . . . . SURFACE HARDENING. . LOCALIZED HEATING KH&gj FORGING . . CONTINUOS^JJ HEAT TREATING . . PRAZM ^lfl ONE OUNCE EIGHTTOTONS ''Tar AJAX MELTING FURNACES PROVIDE: Speed, u n if o r m * ^ low m etal losses, quick changes fro m one alloy to anothercontrolled stirring during the melt. A JA X HEATING FURNACES PROVIDE: Speed, close tempera-a control, absence o f scale in fo rg in g , zone h ardening and a score of a f c f e cations that save time, materials and rejects. A ja x Furnaces produce better results a t a lower total manufacturing : per piece or per pound. Users in m ost cases re p o rt th a t the cost of c is negligible In view o f the results o b ta in e d . EL. E C T R O T H ERMI CORPORATIOI AJAX PAI TRENTON, N . J l M I N I N G T E C H N O L O G Y GEOLOGY MI NI NG MILLING VOLUME 2 NO. 3 MAY, 1938 p. ss7 p . s (j i p. 9oi P. 902 L P. 903 r. p. 903 P. 929 r P 930 " P. 943 CONTENTS Shaft Sinking on the Gogebic Iron Kange Hi W A K noll and J C Sullivan Diatremes and Certain Ore-bearing Pipes B y VO I-I E m m o n s 65-inesh Grinding in Screens By W a l t e r M. St e p h e n Closed C'ireuit with Stainless-steel lime stone Mining at Ste. Genevieve, Missouri B y R a l p h W. S m i t h Geology of the M cI n t y r e Mine, B y G e o r g e B. L a n g f o r d Hecent Imp ro ve me nt s in the Mining Praetiee of the TriState District B y C. W N i c o i .s o x Reaetion of the Living Body to Different Typos of Mineral Dusts with and without Complicating Infection B y L eroy V G ardner Suggestions for the Control of Silicosis in Mining B y D onald E C vmmivga idle Place of Geophysics in a Department of Geology B y VI K i n o H i b b l r t Published every other month by THE AMERICAN INSTITUTE OF MINING AND METALLURGICAL ENGINEERS, INC. Publication Office at 212 York St., York, Pii. Editorial and Executive Office, 29 West 39th Street, New York, X. Y. A. B P arsons EDITORS J, j I\r.xNibDY J r. E H Roim K ^ J a'Vell ui ? 1`2 ^York , v o,rx, Pa M tow d aa coco c OJas1- Matter Jan .:.iv PPM at tin /V - . v> IIII rl~. , ,' *- t. i-, ;-r' 1 The New Magma Copper Mill At Superior Arizona RECENTLY completed, was designed, built, and put into operation by the Booth-Thompson Division of The Galigher Company. This new addition to the mill was built to treat 250 tons of copper-lead-zinc ore, but the flow sheet also provides for the regular-treatment of the Magma Copper Ore and when ? twenty-four hours. ,>Jf^you are contemplating the construction of a new mill, AS v C onJlm yV 35*years'* ^experience In tf^treaBrncnl of oits throughout the world will certainly prove of value to you. PR O FIT-M A K IN G GALIGHER PRODUCTS ` Agitair Flotation Machmes , GGeeaarryy-RJeepahgmengtsFSeaemdperle?rs Bee 'Tee^Gold T rap s Bee Tee Conditioners Bee'TeeaTiltmg Filters BateaClean-pip Amalgamation Fa t.LAsanbt$aollrg_aatronraytjonCDleraensts-iunpg'BKa|qTu^ttpsm. ^enh Ore Testing and M etallurgical ServiC' FOREIGN REPRESENTATION South Africa < , Great B ritain ^ South An G H. L a n g ler & Co L td '249 Main Street JoB L ^N B SunR O H o se in g & H y lto n C arl F 100/c Biackstock Rd. National CityBjyik of N'.-J S m s b u r y B a r k , Lo n d o n , N 4 b c e n o s a ir e s , j Write today for information THE GALIGHER COMPAN 228 S. W. T E M PL E ST. H OOTH-THOM RSON D IV ISIO N SALT LA K E C IT Y ,! : H A R D IN G E MILL in P E R U HARDINGE Serves the World M EN in Foreign Countries can't afford to take chances. That's why they use Hardinge Mills. A Mill that serves the World can do your job! The truss-like construction of the Hardinge Conical Mill means less weight and greater strength--a reduction in dead weight load, result ing in less friction loss and savings in power, 'and smaller upkeep costs, because their cone shape reduces Ball and Liner consumption. W rite for descriptive Bulletin-- today. Hardinge YORK, PENNSYLVANIA, M ain O ffice a n d W orks Y O R K , 122 E. 42nd S t. F R A N C IS C O , 501 H o w a rd S t. C H IC A G O , 20S W . W ac k e r D rive DENVER, 817 17th S t. 1 TR A N SA C TIO N S A . I. M . E. Vol. 126 METAL MINING AND MINING GEOLOGY Metal-mining papers and discussion selected from the material presented before the Institute 1935-1937; Mining Geology (including Aviation), 1936-1937 Thirty-six papers: metal mining, 25; mining geology, 11. T he A u t h o r s: R. S. Archibald, G. C. Bateman, C. H. Behre, Jr., A. Berton, G. N. Bjorge, W. W. Bradley, E. L. Bruce, B. S. Butler, L. S. Chabot, Jr., J. J. Cros'ton, D. E. Cummings, L. T. Eliel, A. H. Fay, J. W. Fehnel, V. R. Garfias, P. W. George, O. A. Glaeser, A. C. Green, E. F. Hanson, T. Hatch, G. B. Holderer, J. D. Johnson, N. O. Johnson, C. A. Kumke, W. Lindgren, J. F. Magee, H. S. McQueen, W. H. Meyer, Jr., C. A. Pierce, W. B. Plank, A. J. M. Ross, S. M. Shallcross, G. Sherman, Q. D. Singewald, S. J. Staple, W. E. D. Stokes, Jr., R. W. Thomas, J. J. van Nouhuys, W. S. Weeks, J. F. Wiggert, E. Wisser, C. W. Wright, L. B. Wright. 633 PAGES Cloth bound, $5.00 to Nonmembers Canadian and Foreign Postage $0.60 extra A copy has been mailed to members of A.I.M.E. who have previously requested it. Those desiring this volume in addition to any other divisional volume for 1937 are entitled to one copy at $2.50. American Institute of Mining and Metallurgical Engineers 29 West 39th St., New York, N. Y. MINING TECHNOLOGY { T h is periodical is the medium through which the American Institute of Mining aud Metallurgical j^igineers effects initial prompt distribution of T e c h n ic a l P u b l ic a t io n s ( T . P . 's ) sponsored b y its Idustrial Minerals Division and its Committees on Mining Methods, on Milling and Concentration |d on Mining Geology. The contents of the annual volume of the T r a n s a c t io n s of the A.I.M .E. gating to the work of this Division and these Technical Committees will be chiefly selected from Ipers that appear in this publication. Papers and Publications Committee Albert J. Phillips, Chairman E. J. K ennedy, J r. Secretary Committee on Mining Methods J. Murray R iddell, Chairman Guy N. B jorge, Vice-chairman M. Leighton 7ice-chairman Industrial Minerals Division J. R. Thoenen, Chairman G. R. Mansfield B enjamin L. M iller Vice-chairman Vice-chairman den H. E mery Papers and Programs Committee G. R. Mansfield, Chairman H. I. Smith J. R. Thoenen Committee on Mining Geology B. S. Butler, Chairman jrles H. B ehre, Jr. Vice-chairman in M. B outwell D. F. H ewett g'F ice-chairman V icc-chairman Augustus Locke Vice-chairman E. S. Moore Vice-chairman ,, Committee on Milling Methods R obert H. Richards, Honorary Chairman E. W. Engelmann, Chairman II. B enedict ice-chairman T. B. COUNSELMAN V ice-chairman Arthur F. T aggart V ice-chairman 5 offers a complete line of chemicals fort centration. IN these past seven years hundreds of mills all over the Mining world have found that Cyanamid Service actually does make chemical buying as simple as an "over the counter" transaction. These mills have benefited by the economies of centralized purchases, combination shipments and bed-rock inventories. They have found that Cyan amid Service disregards distance . . . "that the Rand gets the same service as the Rockies". Just as important many mills have profited by the practical assistance of Cyanamid field engi neers and the Cyanamid Ore Dressing Labora tory in working out better flow sheets and apply ing exactly the right reagents to the ore being treated. They have found Cyanamid Service trustworthy and unprejudiced because Cyanamid Whether you are planning a new' mill < property in a remote district or da thousands of tons of proved ore on a 1 lished lode, you will find that it costs i take full advantage of Cyanamid Servio it costs far less when you consider allij taut economies. ORE DRESSING NOTES No. 7 flotation reagents, the most rapidli phase of flotation. The properties the newest reagents as well as the familiar chemicals are described, pleased to send not only a copy for] as many additional copies as may : others in your organization. AMERICAN CYANAMID COMPAI A COMPLETE METALLURGICAL CHEMICAL SERVICE 30 ROCKEFELLER P L A Z A ............... NEW YORK, N. 6 AMERICAN INSTITUTE OF M INING AND METALLURGICAL ENGINEERS Technical Publication No. 887 (Ci^abs A, Metal M ining, N o. 88) DISCUSSION OF THIS PAPER IS IN V IT E D . Discussion in writing (2 copies) may be sent to e Secretary, American Institute of Mining and Metallurgical Engineers, 29 West 39th Street, New ork, N. Y. Unless special arrangement is made,%discussion of this paper will close Sept. 1, 1938. Any scussion offered thereafter should preferably be in the form of a new paper. Shaft Sinking on the Gogebic Iron Range By W. A. K n o l l .,* Membeb A.I.M .E., a n d J. C. S u l l iv a n f (New York Meeting, February, 1938) T h e sinking of a new shaft at the Newport mine, Ironwood, Mich., as started in May 1931 and completed on Aug. 3, 1932. During this riod, 2665 ft. of shaft in granite was completed, at an average advance f 6 ft. per 24 hr. In November of 1930, experimental work was conucted on 65 ft. of shaft through 22 ft. of overburden where ledge was countered, and this work convinced the operators that all drilling could e done with vertical holes with the blasting relief to a 4 ^ -in . hole drilled ertically in the center of the cut. The reason for not adopting the conventional V-cut was to get away om damaging the shaft steel. The blasting in a Y-cut naturally tends throw the broken material upward, but with the cut as adopted e relief was in a horizontal direction to a large extent. The scheme of ucking employed made it necessary to keep the steel shaft sets within ft. of the bottom at all times. This could not be done without serious mage with a V-cut when blasting in granite. The cut as drilled also ~oke 10.83 ft. per round of drilling, which was considerably more than e experience with a V-cut in the same material. The extended cut duced proportionately the delays for charging, blowing smoke and ndling drilling equipment in the shaft. Another advantage was the ease in drilling vertical over inclined holes, d the preservation of the proper spacing of the drill holes at the bottom the cut. D kelling Air was carried down the shaft in an 8-in. flanged pipe line at a presxe ranging from 95 to 100 lb. This line was extended to within 100 ft. the bottom, where a valve and a 4 by 4 by 6-ft. tee was connected to it. * j|> each side of the tee was connected a nipple and elbow, the resulting |a n of the two elbows being about 4 ft. Lengths of short 3-in. hoses | Manuscript received at the office of the Institute Nov. 26, 1937. | * General Superintendent, Pickands Mather & Co., Ironwood, Mich. | f Mining Engineer, Pickands Mather & Co. r--------------------------------------------:-------------------------------- -------- --- f Copyright, 1938, by the American Institute of Mining and Metallurgical Engineers, Inc. M i n in g T e c h n o l o g y , May, 1938. Printed in U. S. A. 2 REACTION OF TH E LINING BODY TO MINERAL DUSTS ing fibrosis or the formation of scar tissue. This reaction is a result' stimulating connective tissue, the supporting framework that holds functional cells of all organs in place. The connective tissue of the li is composed of the same elements as the connective tissue in the lur although it assumes different forms in the two organs. Since it has b* shown conclusively th at free silica has the same effect upon conned tissue regardless of the organ in which it happens to be located, it has 1 assumed that the reaction to other minerals will also be demonstrable <| connective tissue in any part of the body. Experience is indicating tM this is true except in regard to the fibrous silicates composing the asbestd group. Thus far these substances have had little effect outside the and have produced fibrosis only in that organ. The capacity ol 'an; particulate mineral to provoke fibrosis can probably be determined v equal facility in all organs whose structure permits the accumulation i retention of injected material. The minerals used for the tests to be discussed have been analy chemically and petrographically to make certain of their purity. T have been pulverized in mills, elutriated in water to secure particle*! microns or less in diameter and again analyzed to check their comp tion. By weight 1 per cent and 10 per cent suspensions have been pared in physiologic salt solution and sterilized at low pressures. Rab have been injected by ear vein with 1 gram of particles, administered; 20 doses over a period of 2 months. Guinea pigs have received a sr 200-mg. injection directly into the abdominal cavity. At least rabbits and five or more guinea pigs have been used to test each mine The animals have been killed at intervals during a two-year period ; observe the reaction of the tissues and to determine whether changes progressive nature have occurred. Capacities of M inerals to Provoke R eaction All of the observations have not yet been completed but the &cpanying tables indicate the scope of the investigation and the maxim;' period that each substance has been in contact with the tissues, minerals tested have been grouped in the following classes: 1. Uncombined silica, of which most forms are active tissue irrita 2. Silicates, which in most instances are either inert or productive;:, slight chronic inflammation. 3. Nonsiliceous minerals, which in general act like the silicates. 4. Mixtures of free silica with other minerals, in which the action',; the silica is retarded and modified in varying degrees. Signs Used in Tables The capacities of these different minerals or combinations of mine to provoke reaction in the tissues of living animals have been com- LEROY U. GARDNER 3 and the results indicated by numerals and plus signs in the accompanying tables as follows : indicates the minimum reaction, consists merely of phagocytosis; i.e., the ingestion of the particles by wandering " dust cells." Inert substances apparently remain inside the bodies of such cells for indefinite >eriod without exerting appreciable effects upon the surrounding tissues. + indicates th a t the mineral may be very slightly irritating. As a anifestation, microscopic accumulations of lymphocytes (chronic flammatory cells) are found in the immediate vicinity of the dust cells. 2 + indicates that the fixed connective tissue cells directly adjacent the dust cells have been irritated and there is slightly more evidence if chronic inflammation. 3 + signifies localized nonprogressive fibrosis. The injured connec,ive tissue cells have begun to multiply as a result of irritation but the iroliferation does not progress far and remains localized in a zone close the irritating particles. 4 + is more widespread fibrosis, which is suggestive of silicosis but shich has not attained m ature hyaline form. 5 + represents the standard reaction to normal quartz. The functional tells of the organ are injured and destroyed; the phagocytes, irritated by he silica they contain, are stimulated to migrate and concentrate the articles in focal areas. More tissue is injured by the resultant high local oneentrations, and fibrosis of a peculiar and characteristic type develops, iuch fibrosis takes the forms of nodules about the collected masses of ilica; it may also be diffuse when the particles are so numerous that the ihagocytes fail in their attem pt to remove them. 6 + and 7 + are necessitated by the very rapid fibrosis caused by rystobalite and tridymite. With these toxic substances the phagocytes at constitute the primary line of defense are apparently paralyzed at the tset. The moribund cells do not even attem pt to remove the irritant nd as a consequence the particles are not collected in focal areas. They main scattered and injure the tissues wherever they lie, and the fibrosis a t rapidly follows is diffuse rather than nodular in type. 8 + is used for the very acute inflammation th at immediately follows jections of dispersed colloidal silica and sodium silicate. Often the ocess is so rapid and extensive th at death promptly ensues. In non,tal cases moderate degrees of proliferation or fibrosis may develop later but rapid elimination of the fluid irritant fails to maintain the reacn indefinitely. I Class I --U ncombined Silica i; The following table lists the different forms of free silica which have low been tested and indicates their comparative capacities to provoke action. The responses to all except tridymite and dispersed colloidal 4 REACTION OF THE LIVING BODY TO MINERAL DUSTS silica have been followed for at least a year. Tridymite has killed ev< animal within a period of 3 months. Colloidal silica in the standard do used for all these minerals has been followed for only months. Table 1.--Free Silica Crystalline Forms Cryptocrystalline Forms Amorphous Forms Normal q u artz............... 5 + T ridym ite....................... 7 + 6 + Vitreous silica .......... 5 + Chalcedony.................... 5 + Tripoli (Seneca, M o.). . 5 + F lin t................................ 5 + Colloidal silica, dis- \ fig persed .........................'M g Colloidal silica, gel. .. .h'3j O p a l............................... I S * D iato m ite..................... j |j| In supplementary experiments it has been demonstrated that the do of 1 gram arbitrarily selected for intravenous injection into rabbits | excessive with pure free silica. As small an amount as 0.05 grams quartz will produce essentially the same effects, although at a somewl slower rate. Other injection tests have shown th at the rate of reaction to silica 1 inversely proportional to the size of the particles. A splinter of qua several millimeters in diameter, which has been embedded in the cor tive tissue beneath the skin causes no fibrosis within a period of one ye Intravenous injection of particles 10 to 12 microns in diameter excites? formation of microscopic tubercle-like nodules, which are cellular rati than fibrous in character and which increase very little in size dur a period of two years. The same weight of particles 1 to 3 microns j diameter is responsible for the progressive fibrosis that has been descril as characteristic of quartz. If a gram of particles 1 micron or less diameter is injected in the same manner, acute degenerative cha develop in the organs where they lodge and most of the animals are within 3 months. Obviously the reaction to silica is related to the ante of surface in contact with the tissues. The behavior of the amorphous silicas requires comment. In dispersed colloidal form, silica is a very active tissue poison. In ss doses it causes acute degenerative changes (8 + ), which are followed limited degree of proliferation simulating the early stages of the resp to quartz. When such colloidal silica has gelled, it loses all capacityS affect the tissue. One year after injection the only visible reaction is i presence of phagocytes filled with the particles. Opal, a natural ac phous silica, is moderately irritating and sets up cellular changes, wi temporarily progress like those induced by quartz. Later, however, reaction subsides, leaving a limited amount of scar tissue. On the oil hand, celite, an amorphous silica composed of siliceous diatome provokes a progressive fibrosis indistinguishable from the read to quartz. LERO Y XT. G A R D N E R 5 Class I I --Silicates The artificial silicate of sodium, not listed in Table 2, has an effect very much like that of dispersed colloidal silica (8 + ). When injected in the standard doses its effect is uniformly fatal. Minute repeated doses totaling 13 mg. when injected directly into the lungs of guinea pigs failed to produce fibrosis after a period of 4 months. The other silicates, with the exception of the mica, biotite, have [generally proved to be as inert as silica gel. M ost of them have provoked |only the initial reaction of phagocytosis (+ ) or have produced very slight | degrees of chronic inflammation (+ ) in the immediate vicinity of the dust-filled cells. Talc and muscovite have caused a little more extensive [inflammation (2 + ), but with the former this change has shown no tend:iency to progress in 2 years. The response to both muscovite and biotite |has been under observation for only 6 months, but in this period biotite | has excited definite proliferative changes (3 + ), which now look as if they would progress. The ultimate effect cannot yet be anticipated. It is of interest to note that the two sericites are almost inert. One of them was selected by Professor Larsen, of Harvard, as a fibrous type comparable |to the form that Jones believed was an im portant cause of silicosis. [ Table 2 lists the various minerals now under investigation and indijcates their comparative irritating powers for the maximum period of observation. The " deaths" noted in the rabbits injected by vein are of jjmechanical origin and are of no significance to the subject under discus sion. A larger unit dose of the same minerals has had no effect when Ejected into the abdominal cavity of guinea pigs. The experience with the finely ground asbestos minerals, anthophylite, amosite, amphibole, crocidolite and chrysotile, has been most instruc've. In the liver and other organs none of them has caused even a ggestion of the fibrosis th at characterizes the picture of pulmonary bestosis. Furthermore, there has been no formation of asbestosis jodies, those peculiar structures always found in human and experi mental asbestosis of the lungs and due to a deposit of iron and albuminous aterial on the surface of the fiber. The absence of reaction in extrapulmonary tissues to fibers ground as finely as these (3 microns) consti tutes part of a chain of evidence which may ultimately demonstrate that the fibrosis in pulmonary asbestosis is due to mechanical irritation by ng, flexible, mineral fibers. In the lung, which moves actively in espiration, such foreign bodies would be more apt to injure the tissues .echanically than they would when embedded in a relatively immobile _;an like the liver. If the irritation from asbestos were chemical in (feature one would expect th at it would affect connective tissues in any part If the body and th at fibrosis would develop most rapidly upon injection of irery fine particles, which present such a large surface to the tissue. 0 H h l("]'( l \ Ol T l i K l , L \ l \ ( i HOD'i U) M l \ K l i \ l , 1 U M l'y m .i. 2. 1 '.Uifi'io s y m i >n r u h M i e ht OU H Air s a U u i : KV 14 ER \ oh vch eus and !Ud'n-:v (; cuip \ .net}- Maxi mum '1 n:u* Oh-^ Months i A n h \ cirons PlllvMlllMt 0 S (K:Sl.,0i M e ta silio a t es Kuldspai X a-M icrocim e 24 tR SiO y V \ roxciio R hodonite 0 A m phibole A m hopliyllne 12 nioM t e- G fibrous X a-Treiiiolite G A m phibole 3 C ro c id o h te 6 Beryl 1 O n h o s ih e a t us i. R 2S i 0 4) . . G aniel Topaz Hydrous : H 20 c r v s t a l l i - za ion. . Xeoht c H .0 es-ent ad M ica Alm aiidite? 24 Sdlim am te 24 A nalciie i 24 M uscoc le t) i Serieitofibrous 21 Sencito-plat y 24 i B iotne 2 ; S e rp e n tin e Serpent ire 0 and O h r \ s o t le1 9 Talc 1 bale 24 ( l i a 11 c o i 1 1 1 o 12 !t t ) ^ n,, 1, p;,a.,,,, 3 Ilalloysito 0 M ontioor'- 0 JU J ; J M y ' \ ,i', T11 M1' ' 1 s i ] , - T e a i , h r, hrbtm r M axi- mu m Tune M onths 1 '1 is^ue UmiH.o* - 12 0 -+- i 1 2 r 4 +!s -r s A s T 0 D eath- r 12 r 12 A - U A N ot to U a y 12 2 + 1 -r 12 - 12 D eaths T> ___ 9 1 D o n t lis _ 12 -r 4 D o n t lis 1 o ] 2 -- 12 D eaths -- , i 1 ) ' U" 2 -y ,________r 1 u N o t to\.' 3 + ; N o t t<>\. T j N o t torn. 2 + 4- N o t t(iv. 2 -- 2 -T - U i ].];<n i u r i n > \ i :k The ca rbte of mIk-oii fSi(' i an artificial compound widely used as abra hue produced prucUcaliv no reaction Th e masses of particles lie mort in the tissue for years wi thout provoking more t h an a strictly localized, nonprogrc-sMve chronic inflammation of slight degree. Animals inhaling high foiiceuliarions of this dust for 2$4 years have shown no more reaction in the lungs than has been discovered in oilier organs after injection subcuuuieous injection, lias excited neither inflammation nor fibrosis. Colorimetric tests for the a m o u n t of soluble silica, liberated in the heat-sterilized, saline suspensions of different forms of free and combined silica are now being made. As far as this part of the work has progressed, it has been impossible to establish a ny correlation between the degree of solubility a vitro and the capacity to provoke reaction in the living body. If anything, the least active forms of silica seem, to be the most soluble. The inert, silica gel yields 126 6 parts of soluble silica pm million while the very active quartz gives a figure- of 6 6. The solubilities of the silicates vary widely, as might be expected; lialloysite showed a solubility of 4.5 j).}).m , while amphibole gave 43.7 and glauconite 52.3 p.p.m. I t is emphasized that these figures represent solubilities in unbuffered isotonic "sodium chloride solution. When similar tests have been made at the pH of the body in serum or other fluid, un doubt edl y there will be differ ent results, Inn it hardly e-eiin probable t h a t the existing ratios will be reversed. C lass III- -NoxsTiuenors M ixerals Table 3 shows that, except for the toxic sulphides and dolomite, the nousilieoous minerals like the silicates have very little effect upon the tissues. Dolomite is readily soluble and its high alkalinity undoubt edl y is responsible for the effects produced in tin- concentrations injected. By Inhalation, r t icios (amid enter the lungs at one time t h a t the K'id-baso equilibrium of the body would not bo disturbed Certain generalizations are permissible even at this incomplete stage vf the studv Klee silu obviously capable of producing a rapid and [progressive fibrous reaction, winch no other mineral can even approxi mat e. The sdicatcs, as a class an- not irritating suhst nnee" rYcrnti.-'.n-i' species possess n nt at mg pi opt rties whose nature 1las not yet been defined. JlXon,siliceous particles are inactive, except the minerals t ha t arc definitely pt-oisonous T)icm o b s r n m h-o- are not nr v : Wet -imph coniine what if cas loip ht on r o o o c 11 i/s-d ft nerailv accepted befit1 Coal the pvni,erln-s of 1--1> j---s.. W s R E A C T I O N O K T U K U Y 1 M I 1101)1 T O M I N E R A L D O S T S of investigators, does not satisfactorily explain all the observations th.n have been presented in this paper. Our demonstration of a marked variation in reaction to different f o r o of amorphous silica suggests t h a t if solubility plays any part in the procev it is not the only one. The form in which t he soluble material exists probably much more, import ant as indicated b y t he loss of activity ass-.~ T able Ncusiliccous Mineral's Effect on Habbits Guinea Pigs Other Tebts Mineral Ma x i mum Period Ob served, M onths 1 1 Tissue ; action . Maximum Ob- M onths Tissue Reaction Maximum Period i Observed, M onths Tissue Tvpe a R e a c Test, tion D i a m o n d ........... ............................. | 36 j + Coa l, b i t u m i n o u s .............................. , 1 2 i 2+ 12 Coal, a n t h r a c i t e (1 76 per c e n t I S1O 2) 12 ! x 12 A l u m i n u m o x i d e ....................... ! 24 12 Rutile .......................... j | 11 1 1 M a r b l e .......................................... Gypsum, satin spar ... j 3 i _ + i 41 3L 0-r 11 3 31 G ypsum , calcined . .. . 6 Galena . . . . C h a l c o p y i i t e ............................ I r o n s u l p h i d e ................................. I Zi nc s u l p h a t e (r oa s te d su lp h id e ) j 11 1 F l u o i i t e (S 1O 2 0 8 p e r cen t) . . j IS Dolomite . . . . ................... 4 0 d a y s 0 5+ 2 -t- (Cal cif ) 24 8 Abscess and repair 8 S t 2 + 12 2+ 1 H + 0 Deaths Toxic Abscess fi brous, repair ! 2+ . Deaths 1 Inhaled 0 SubQ - SubQ SubQ . 0 SubQ InhSuKL = Inhal*-:: 1 i l.KKOI 1 UAUDN EK 9 i able 4 indicate.") the Quantities of free silica, administered in associa tion with other minerals th at have iailed to produce fibrosis in various periods ol observation, d h e injection of 3.3 grains of granite dust t h a t was proved to contain 1 gram of quartz did not cause as much reaction in a year s time as the quartz alone provoked during the period required for its administration. One gram of the particular sample of South African mine dust employed contained 0.7 gram of quartz, an d yet after 16 m o n t h 1' of contact with the body the response had not at tai ned a mature stage. The reaction was not nearly as extensive nor as advanced T able 4.-- Mixtures of Silica and Other Substances Effect on M ineral an d Silica C ontent Rabbits Guinea Pigs Maximum Period Ob served, M onths Tissue Reac tion Maximum Period Ob served, M onths Tissue Reac tion Maximum Pci lod Ob- M onths "Tissue T y p e of R e a c "Test tion H e m a tite (6 pei c e n t SiOz). . . . 12 A n th r a c i te (10 13 p e r c e n t S 1O 2) .. 12 + C r u d e f lu o r i te (10 39 p e r c e n t S1O 2) . . . . 12 3+ G r a n i t e (35 p e r c e n t S1O 2) 15K 4 + . 12 2+ standard dose (0 3 giam S iC R ) 3ar s t a n d a i d d o s e (1 0 g i a m biCR) . 15 3+ 12 2+ F e u u g in o u s ch e rt (50 per cen t SiCh) 22 3+ s t a n d a r d dose (0.5 g r a m S 1O 2) . . . 12 4+ 2 x s t a n d a r d do se (1 g r a m SiO T 19 5+ so A f r ic a n m i n e d u s t (70 p e r c e n t S1 O 2) 16 4+ 12 + 42+8" + 12 + 21 0 11 2+ 11 * Inhaled 12 3+ 30 2+0 22M + + 12 3+ 26" 12 3 + 12 3+ " 42 m o n t h b 111 t h e d u s t i n g r o o m + 8 m o n t h s m a n o r m a l a t m o s p h e r e , a n d , s im i la r l y , 2 2 ^ 2 m o n th s m the du&tmg 10 0 m + 26 m onths in a norm al a tm o sp h eie b In one 01 tw o a n im a ls n o d u la r fibrosis (4-j-) d eveloped 111 the l y m p h n o d e s d ia m in g th e lu n g s b u t pulmonary fibiosis was lacking ciated with gel formation in colloidal silica. Here again more observat: is necessary before any conclusions can be reached. Class I V -- M ixtures TLr. 1na+ m i m of minerals to be dCciW'-wd includes natural and ar m i. ficial mixtures of free silica and other substances. In m any respe: Ihese are the most important, for mixtures rather t h an pure silica ; encountered in most industrial atmospheres. Only part of the beha* rlafbj of the mixed dusts can properly he discussed in this section (leading w inieepa] mot cri al It whl he sboun that ior the period of obsn VGtlO'u pnWCJHA. Ulr M, ila.1n' an. ut ,'m,j.1.1.K. fuli.>. " wi 1.1 VOM e m o l l l i f e Ms ,l' . . . . . . ll.M. VP I r u ]' ]"' 1 In' eompopoiM- oi i as that provoked by 0.5 gram of pure quartz in l l h months. At the opposite end ot the s e n e s is hematite, a gram of which contained only 3 mg. of free silica Since this quant it y is only about one-tenth the amount ol pure quartz necessary to cause fibrosis, it is not anticipated that silicotic reaction will ever develop. t lie observations to date make it seem probable that if a mixture contains much more than the minimal effective dose of free silica, fibrosis may ult imat ely develop but, at a very slow rate'. The time required >nd the character ol such fibrosis will probably var y with the properties .4 the adulterant dust Some oi these substances seem to be more potent 'ha i, <>l i i e i i n tempoi ;n by i n h i b i t i n g llu action oi Mica, 1 oi c\,amide. 10! 0 at !(! 13 per cent of - can- al a. piango A l 1' ' no non li).39 m , ); in s i t ; ] i <j ' i t u s i i i i i 11 \ i a n ) j j : i a l or a: ad. a.t (.<t i l c J u s i o o n o o U- \ c t m e u ; i 11] , H um wn- i( t 'i 11 (1; rougholU (he \ a r u m s ;i 'P'";iK (!, leu l i b! !;, T h e Min.i 11_cc 1)a ];i' i!)- undoubtedly oiDerate <- lung- t i l t a c t u m o'; silica inhaler t \ n h other dust I:i addition, siliceous an oi li rr k i n d s <if i in i'll rlt - n a i ] I n m o'o ] n f i ) , >1 1 n \ phcrc. TJu* resultant aggregate are so heavy t hat t hey ml! to the groan . or so large t ha t t hey cannot be inhaled. T h u effect r e t a r d ' the accumula tion of dust in the lungs The right-hand colum n' oi Table 4 indicat- i'ow \ cry slight luu been the response to prolonged inhalation of differ/ mixtures. The at mo-phenc com entratioiu m these expo: inn lits liav- been high, aIn ays m exec-- oi 500 million particle' per eubm foot of a:: (light-field counts; and in many i n s t a n ce ' m excess ol 800 million In x animal has there been appreciable reaction in the lung', ami much less ~ suggestion of nodule formation With crude fluorite and granite, earl; silicotic nodules developed in the lymph nodes draining the lungs; wit pure quartz, on the contrary, an exposure of 12 to IS mont hs to a con centration of only 100 million particles per cubic loot has produced gen eralized nodulation throughout the lung- The varying degrees of tisu- rcacuoii are paralleled by the amount el 'hit a detected by chemicm analysC' of the l ung' Alter 22 months inhalation ol (`h e n , for examr.b the lung tissue revealed 10 25 per cent of ash. of which T l S per cent v.n- sihea Alter 19 1>months m one-third the concentration of pure q u a r t the lung yielded 12 27 per cent of ash ni di a silica content of 39.0 r e cent Thus it is concluded th a t the substances other t han silica in mix- ,, dusts play an important part m modiiving i t ' inlhionce on the body, ax - that the hazard from such dusts w not only proportional to the quant::; of free ' i l i c a but i s inversely modified by tin other component '. 1 J X !-'].( ] JO \ 1 Yo coup nnUomi jul A tin' el l o c i o: n 1 ;ib'd (iu-is <)']< ]]111s; lie. V P Is non ledge oi' tin infiuenee of mi io t io n ' V11y ioi'Ii oi , of tin i j o t l y i v Inch tissues art olaijj,a^(d ! 1}jv t s). j uos 111Y( 1J' i!'s m ill I su~] m ss ' Oi oils, os i 1WAf 1A l llA TtllK r i h i ' o ' ns a w n m . i l a) uc s, 's1 11" & 1 ' 1'ds t o re; r n , lm t uia ! 0(|hj- !ll(lh! Cif! Ah'-j n niio i :a p m p A / n ' <i i; i s; S1;i 11 | )-I \ OI 1 S- ) -i 11 <1'('(! ' i ;f r ' Tlit 1in A 1, " n o I 1', 5! iY1A %-;r mi' ;' i,u - c\ i 1 i,i 11' >,, O, , d o , . . Os , . . \ ,i> ` ........ e 1 " ' ' i ` a. ' 'A! : ,,' V - 1sH*> I ~i 'i.cmwjJitiUtiSfiSES 1,0' i (, \ !i D\ u ; - l > fN*'j x u p o n ,,) t .b.-.vUo-i-. S u n i.-t icai u n a i v s c - si.wnu<; i 11a I - uc b i n d i v i d u a l - b a t e n u m b m o:'!' l u b n r c u l o - i - t )i : cotiicm- moni'K-r- o! t ! popuhomn, and ti.nl tlu-, injection is often extremely o] runic, cau-ing >ym])lom> only m tin' liter years-- of iiic. K\|HTinicntaJ methods Hive duplicated tlumo findings m animals and nmm,.n ..... .... ; dial ai r oj -omo value m understanding t he ntecha- m-iii' involved. Time1will not permit a delaik d discussion of 1hi.-, pha-e of t io .subject Here it suffices to state t hat of t he different minerals- tested only free silica has a c cry marked influence upon susceptibility to tuberculosis. \\ itli calcium compound- there i- a tendency to deposition in the areas of tuberculous degeneration and an accelerated healing ol the infection. Some oj the noiisilieeous dusts eause -light loeal extensions of the infec tion, which quickly heal to form -mall sears. The silicates as a class- i have not yet been proved to be any more potent than nonsihocous min erals On the other hand, free -ilica, in the body at lca-t. -eeum to have a specific stimulating effect upon the growth of tubercle bacilli These organisms grow with unusual rapidity m tissues being killed by high loeal concentrations of silica: in old silicotic scars t hey arc able to remain alive for long periods of time but ('ease to multiply aeti\ ely. In human beings with quiescent encapsulated loci of tuberculosis, phagocyte- m a y in time transport enough silica panicle.- into the foci v here the bacilli are localized to cause them to multiply and spread. The disea-e t hat result- is the extremely chronic combination of silicosis and tubemilo-is known as 11-ilicotuberculo-isd' The same condition a p p a r ently can al-o he produced by new imeeiion from tut bout, in silicotic1 subjects with marked i mmu ni t y to tuberculo.-is. Whether the- m ec ha nisms governing such i m mu ni t y are altered by silieo-i- has, not boon disom ored In -llicotic animals and in men with no immunity to tuber culosis, a first infection with the tubercle line dins aftei the tea-turn to dust is inatuis pioduces an unusually acute reaction ("povinoduhn- tuber- cnlo.-i-" ), winch t e rm in at e' mindly F o i u m a t c h such cases arc rare Mi \ inr e- of silica and materia)-- like la-mat ite and coal wax muse v. id, -pic-ad extensions <.1 i m- ' ' ncuimg \\UI) 1he l o t mat mi) oi in a. -si \ c - c a n - Po--ilily ,-oine of the -n- c.d'cd i ongiomcrnU type- -I simple -ill! in 'nnnan being- aff-c O, d m n u n c Wiua 12 KEACTION OF THE LIVING BODY TO MINERAL DUSTS Being organs connected with the outer atmosphere, the lungs would soon become clogged with foreign material if they were not protected. They have a system of filters to prevent dust and bacteria from entering and another system for eliminating such particles as pass the first line of defense. The filtering apparatus is found in the tortuous passages of the nose, throat and wind pipe, which are lined with a sticky, mucous mem brane, covered with vibratory hairs whose motion, like that caused by wind upon a field of grain, wafts foreign particles toward points from which they can be expectorated. The eliminating mechanism consists of the wandering phagocytes, or dust cells, mentioned in other organs and a system of fine drainage vessels, the lymphatics. The latter are found in the pulmonary framework, chiefly in the walls of the blood vessels, bronchi and some of the partitions dividing groups of air spaces. The dust cells move freely over the inner surfaces of the terminal air spaces and ingest any particles that may be present. They carry the foreign material to the lymphatic vessels, by which both cells and their contents are transported to lymph nodes. The latter act as sedimenting reser voirs ; they are located both in the framework of the lung itself and in the connective tissue about its root. By these means the delicate membranes forming the walls of the air spaces are kept clean and in condition to permit a free interchange of gas to and from the blood capillaries that they contain. The mechanisms are adequate for ordinary atmospheres. It is only when man thoughtlessly pollutes the air he breathes with excessive quan tities of fine dust that his protective apparatus fails him. When this : happens the dust cells begin to accumulate in the delicate connectivetissues about the lymphatic vessels and are no longer eliminated. If the exposure continues, they form larger collections in these locations and then gather on the walls of the air spaces themselves. The fibrous minerals of the asbestos group present an unusual problem to the protective mechanisms. They are too long to be transported by mobile dust cells, consequently they are rarely found in the lymph nodes' inside or outside of the lungs. Most of them remain in or upon the walls.; of the terminal bronchial tubes, where they irritate (perhaps by median-'1' ical means) and cause a fibrosis, which gradually extends toward the) periphery of the lungs. The injection experiments already cited indicate the effect that differ-* ent forms of mineral particles may be expected to produce upon connec tive tissues. If any of the particulate dusts should accumulate in the" lungs in appreciable quantities, it will have the same effect in this organ) and its associated lymph nodes. The active forms of free silica that arej inhalable should produce progressive fibrosis. Asbestos will cause] fibrosis, though in another form. Other mineral dusts with a few possible) exceptions will have little effect. LEROY U. GARDNER 13 N onspecific Pneumoconioses The nonsiliceous materials and most of the silicates as they accumulate in the lymph nodes and in the connective framework of the lungs cause pigmentation, with or without microscopic accumulation of inflammatory cells in the immediate vicinity of the dust. The walls of the air spaces themselves are involved only after very unusual exposures. The gross effect upon a lung thus involved is to produce linear and focal deposits |Of pigmentation throughout the organ. The largest ones occur in the vails of the branching treelike blood vessels and in the lymph nodes. iSmaller ones are found in the partitions between groups of air spaces. All jpf these deposits are soft and impalpable because there is no associated ibrous reaction. The shadows of such changes on an X-ray film appear largely as a thickening of the treelike branches of the blood vessels. The lymph nodules inside the lung are too small to cast an appreciable shadow; Ihe larger ones at the root are not dense enough to offer any contrast with |h e shadows of other structures immediately about and over them. In X-ray pictures, linear exaggeration is characteristic of the reaction all the nonspecific types of dust. It may also be produced by some ironic infections and by hardening of the pulmonary arteries. From Etere examination of a film one cannot determine the cause. This is not iunfortunate as might be inferred because such alterations do not interire with the function of respiration and do not give rise to clinal symptoms. Silicosis With free silica the initial reactions are essentially the same as those ipth other dusts. But the irritating particles kill the phagocytes when po many of them are ingested and in smaller numbers they stimulate acreased migratory activity. Wherever the cells concentrate enough jica particles in contact with connective tissue, the latter undergoes iiaracteristic proliferation terminating in nodule formation. Since the iphatic system collects and concentrates the particles in the lymph odes, the first evidence of silicosis occurs in these organs. When only a tie silica has been inhaled the only changes th at appear may be found the nodes. The development of fibrosis in the sedimenting areas literates the channels and the efficiency of the drainage system is ipaired. Subsequently inhaled silica now accumulates in and about ilymphatic vessels inside the lungs. A mixed linear and nodular type fibrosis ensues. The shadow on the film at this stage cannot always be ierentiated from that produced by other forms of dust. Generally, itw e v e r , minute nodules develop simultaneously in the walls of the air ices. Only when the nodules in the latter position become large enough 14 REACTION OP THE LIVING BODY TO MINERAL DUSTS to cast definite shadows is one justified in making a diagnosis of silic when supported by a history of exposure. When enough silica has b inhaled and large numbers of " discrete fibrous nodules are uniform distributed throughout all portions of both lungs," the disease is matu Silicosis will then progress regardless of further exposure. But t. progression is self-limited. The nodules will attain a maximum diame of 4 to 6 mm., and then they cease to grow. They never progress u~ the whole lung is replaced by scar tissue. In this stage of " disc nodulation" there are still large amounts of uninvolved lung tissue ca able of carrying on the function of respiration. As a consequence, sym toms are not necessarily produced. The subject may be somewhat sh of breath on sudden and unusual exertion. At his customary work he generally unaware of any limitation. He has nonclinical silicosis. This is the classical picture of silicosis th a t has developed in an oth wise normal lung. If portions of the pulmonary tissue have been d~ aged by previous infection or by other causes, the silica is deposited loc in excessive quantities. The irritating particles act upon the previo injured cells and accentuate the existing inflammatory reaction. A sive area of diffuse fibrosis ultimately develops in this location, while other parts of the lungs the customary discrete nodules are formed, the massive fibrosis reaches the pleura, this structure participates in reaction and chronic fibrous adhesions develop, which fix the lung to chest wall so th at it cannot move with respiration. To compensate the obliterated air spaces, those in other parts of the lung dilate, produ the condition known as emphysema. The man with areas of mas fibrosis and associated chronic pleurisy and emphysema is short of brea This symptom may be so severe that he experiences it even while at He is almost always disabled and often totally so. Silicosis with Infection One of the puzzling features of these cases of massive fibrosis is t origin. In the particular case, has the scar tissue developed upon basis of an infection that has healed and is free of living bacteria or the organisms th a t caused it still alive? This leads us to the subject tuberculosis, the most common type of infection to complicate silic Tuberculosis may arise from latent infections, which were establis before the subject had become silicotic, or it may result from new ii tions, acquired subsequently. Tuberculosis complicating silicosis is to be unusually chronic, the area of disease is often detectable in an X ! film for years before it gives rise to the ordinary symptoms and be tubercle bacilli appear in the sputum. For these reasons it is hand differentiate from conglomerate silicosis developing in lungs damaged a healed infection. The physical examination and the clinical beha of the subject may give a clue but in many cases symptoms are absent LEROY U. GARDNER 15 only repeated X-ray films taken year after year to determine the rate and extent of progression can establish the nature of the underlying cause. When the conglomerate disease is due to an infection th at is still active, it manifests itself ultimately by the symptoms of intoxication, fever, loss of weight, malaise, etc.; but by this time the localized area of fibrosis has broken down and perhaps formed a cavity; and tubercle bacilli have appeared in the sputum. Anyone can now recognize the condition as tuberculous. From this time on the patient becomes rapidly worse and is generally dead within a few years. There are other forms of tuberculosis in the silicotic, a very rare, acute form and a somewhat more common one, which from the outset behaves like tuberculosis in the general popula tion. These offer few diagnostic problems because they cause charac teristic symptoms. Simple silicosis can and is being prevented. In its discrete form, as it develops in normal lungs, it causes so little disability that the existing cases are not a great problem. In its conglomerate form, on a background of previous injury it causes dyspnoea and is disabling. The cases th a t have already developed must be pensioned as they become disabled; the system of preemployment examination and the measures for reducing atmospheric dust concentrations will probably prevent more from occurring. The great problem remaining before us today is the prevention of new tuberculosis in men who already have silicosis and the treatm ent of the silicotuberculosis th at has developed but is now in latent stages. The way has already been charted for the prevention of new infection. Treatment demands new methods, for those now used so satisfactorily for ordinary tuberculosis are not yielding encouraging results. This is the challenging problem th at must be solved.