F e b . , 1914
T H E J O U R N A L O F I N D L - S T R I A L A N D E N G I N EERILVG C H E M I S T R k’
s t a g e s : T h e f i r s t , when i t is s a i d : “Such a t h i n g is a b s u r d or impossible.” T h e secoiid s t a g e , a f t e r t h e p a t e n t descriptions h a v e become public, a n d h a v e given o t h e r s th; m e a n s t o i m i t a t e a n d t r y t o find loopholes i n t h e p a t e n t claims, begins when i t is s a i d : “ T h e t h i n g is n o t new.” A n d j i t i a l l y , a f t e r t h e usefulness of t h e i n v e n t i o n h a s become so obvious a n d t h e details connected t h e r e w i t h h a v e p e n e t r a t e d t h r o u g h t h e h a r d skulls of t h e laggards. t h e n it s o u n d s : “ T h e r e is n o i n v e n t i o n a t all.” Lawyers are great i n this game. Hyatt’s invention w e n t t h r o u g h e v e r y one of t h e s e t h r e e s t a g e s a n d were i t n o t for t h e P e r k i n M e d a l , m a n y of us m i g h t h a v e f o r g o t t e n t h a t t h e r e ever was such a m a n as H y a t t , a n d t h a t t h e r e mas a t i m e when celluloid did n o t exist, o r involved v e r y difficult problems. His p a t e n t s were assailed o n t h e g r o u n d t h a t o t h e r s before h i m h a d used solvents a n d c a m p h o r in con.junction with nitrocellulose, b u t i t was studiously o m i t t e d t h a t his predecessors h a d used these ingred i e n t s u n d e r e n t i r e l y different conditions, for entirely different purposes, a n d could n o t produce i n t h a t w a y , H y a t t ’ s valuable technical effect. T h e r e r y solvents which p r o v e d a b a r t o a n y i m p o r t a n t applications for molded plastics, H y a t t did a w a y w i t h , when h e con.ceived his t h e r m o p l a s t i c mass. Some of t h e e a r l y d r a w b a c k s i n t h e technical applications of H y a t t ’ s discovery were none o t h e r t h a n chemical experts with which his financial backers s u r r o u n d e d h i m . H y a t t k n e w n o c h e m i s t r y , b u t he knew well observed f a c t s i n t i m a t e l y connected with t h e details of t h e work h e h a d u n d e r t a k e n . His knowledge of nitrocellulose was o b t a i n e d piece-meal b y his own experimenting. F a c t s f o u n d i n books h e a c c e p t e d o n l y a f t e r he h a d verified t h e m . It so h a p p e n e d t h a t h e f r e q u e n t l y noticed t h a t p r i n t e d s t a t e m e n t s d i d n o t agree with his o w n observations. One of t h e chemical e x p e r t s insisted t h a t “cellulose was cellulose,” regardless of t h e source of s u p p l y , provided i t was sufficiently purified, a n d t h a t nitrocellulose m a d e f r o m a n y k i n d of p u r e cellulose h a d t h e s a m e properties. H y a t t knew b e t t e r when h e f o u n d t h a t t h e article
c
91
m a d e f r o m r a m i e , t h e strongest a n d most expensive cellulose, was i n c o m p a r a b l y superior t o t h a t o b t a i n e d f r o m c h e a p c o t t o n o r cheap p u l p cellulose. Some chemical experts also m a d e t h e positive s t a t e m e n t t o his b a c k e r s , t h a t his process would surely l e a d t o terrific explosion because he was h e a t i n g in a h o t press n o t h i n g less t h a n g u n c o t t o n , which was k n o w n t o be a violent explosive. T h o u g h H y a t t s t a t e d t h a t h e h a d been using his process for q u i t e a t i m e a n d still was alive, i t was objected t h a t t h i s was simply d u e t o sheer good luck which would cease a t some t i m e ; if ever i t h a p p e n e d t h a t b y accident or carelessness, t h e h e a t in his presses rose a little higher, a violent explosion was b o u n d t o occur, a n d t h i s n-ould be t h e e n d of t h e celluloid i n d u s t r y . These a r g u m e n t s were n o t b y a n y m e a n s w i t h o u t logic. ,4t t h a t t i m e , it is d o u b t f u l w h e t h e r a n y chemist who knew t h e chemical properties of nitrocellulose would n o t h a v e t h o u g h t i t t h e height of folly t o h e a t t h i s s u b s t a n c e u n d e r pressure. H y a t t n o t being a chemist, preferred ’to t r y a n d see for himself w h a t would occur. H e t o o k a good-sized block of celluloid a n d h e a t e d i t i n t h e h y d r a u l i c press a t a t e m p e r a t u r e f a r superior t o t h e relatively low t e m p e r a t u r e s he was using i n practice. H e tells me t h a t h e was sufficiently impressed b y all t h e . t h r e a t e n ing t a l k of t h e chemical experts t o screen himself f r o m t h e press b y m e a n s of several thicknesses of cross b o a r d s behind which h e could p e e p o n a n d see w h a t was going t o occur. After t h e t e m p e r a t u r e rose t o t h e point when t h e celluloid began t o be d e s t r o y e d , t h e block s t a r t e d sizzling on a c c o u n t of t h e emission of gaseous p r o d u c t s . But h e c o n t i n u e d t h e experiment u n t i l he m a d e s u r e t h a t n o t h i n g worse occurred t h a n t o spoil t h e material. T h e pessimistic chemical experts h a d failed t o t a k e i n t o consideration t h a t t h e i n t r o d u c t i o n of such a large p r o p o r t i o n of c a m p h o r h a d profoundly modified t h e properties of nitrocellulose. T h e y h a d also over-. looked t h e f a c t t h a t soluble nitrocellulose is n o t nit r a t e d so m u c h a s t h e more explosive higher n i t r a t e d cotton. L. H . BAEKELASD
ORIGINAL PAPERS THE C O M P O S I T I O N OF P A I N T V A P O R S B y HENRY4 GARDIER~
Received December 18, 1913
Freshly p a i n t e d surfaces give t o t h e s u r r o u n d i n g air a .peculiar odor. I n closed rooms, t h i s odor is pron o u n c e d . Its n a u s e a t i n g effects a r e well k n o w n . P a i n t e r s a r e i n t h e h a b i t of s t a t i n g t h a t t h e v a p o r s of fresh p a i n t h a v e a “ l e a d y smell.” T h i s is p r o b a b l y d u e t o t h e f a c t t h a t white lead is used a s t h e base u p o n which t h e m a j o r i t y of p a i n t s a r e p r e p a r e d . T h e p a i n t e r h a s t h e r e f o r e a l w a y s associated t h i s p i g m e n t with t h e characteristic odor of fresh p a i n t . Some cases of illness a m o n g p a i n t e r s h a v e been ascribed t o t h e effects of p a i n t v a p o r s . People occupying freshly decorated sleeping rooms which a r e n o t well v e n t i l a t e d , h a v e a t 1
D C.
Assistant Director, T h e Institute of Industrial Research, Washington,
t i m e s complained of illness f r o m t h e s a m e cause. E. C. Baly’ examined spectroscopically t h e v a p o r s f r o m basic c a r b o n a t e - w h i t e lead p a i n t , a n d f o u n d el-idences of metallic lead t h e r e i n . T h e v a p o r s f r o m basic sulfatewhite l e a d p a i n t o r zinc oxide p a i n t . when examined in a similar m a n n e r , showed t h e absence of metallic cons t i t u e n t s . Some cases of lead poisoning a m o n g p a i n t e r s could be ascribed t o t h e v a p o r s f r o m basic c a r b o n a t e white lead p a i n t s , if l e a d c o m p o u n d s could a c t u a l l y be f o u n d present in such vapors. X r m s t r o n g a n d Klein,? a f t e r conducting a n e l a b o r a t e series of t e s t s , concluded t h a t lead is n o t present i n t h e v a p o r s f r o m white l e a d p a i n t . b u t t h a t t h e toxic effects produced b y such v a p o r s are d u e a l m o s t entirely t o t h e volatile cubs t a n c e s given off b y t h e t u r p e n t i n e present. 1 2
The Ozl a n d Colouv Trades Journal, May 6, 1911, p 1518 J . S C. I , 34, 320 (1913)
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T H E J O U R i V A L O F I ; V D U S T R I A L A N D EiTTGIYEERING C H E M I S T R Y
T h e writer h a s m a d e a series of t e s t s which confirm t h o s e of A r m s t r o n g and Klein, insofar as t h e i r results are concerned w i t h t h e non-metallic c o n s t i t u t i o n of p a i n t v a p o r s . The writer’s t e s t s , h o w e v e r , s h o w that t h e vapors from paint apparently contain carbon monoxide, the poisonous n a t u r e of which is t o o well k n o w n t o b e c o m m e n t e d u p o n . T h e a m o u n t of c a r b o n monoxide e v o l v e d is also s h o w n t o b e directly influenced b y t h e t y p e of p i g m e n t s used i n t h e p a i n t . The definite presence of a l d e h y d e s and organic acid s u b s t a n c e s i n p a i n t vapors has also been established b y t h e s e tests. T h e d a t a p r e s e n t e d has b r o u g h t f o r t h considerable i n f o r m a t i o n r e g a r d i n g t h e p h e n o m e n o n of oxidation as a p p l i e d t o linseed oil a n d linseed oil p a i n t s . T h e results a r e g i v e n w i t h a view t o a w a k e n i n g f u r t h e r res e a r c h w o r k of a similar n a t u r e . An outline of t h e t e s t s m a d e is h e r e w i t h p r e s e n t e d , t o g e t h e r w i t h a s u m m a r y of t h e results o b t a i n e d and i n s o m e i n s t a n c e s a discussion of t h e data. Many of t h e tests outlined were m a d e in d u p l i c a t e . EXPERIMENT 1.-Four cylinders each 30 in. long and g in. in diameter, were formed of galvanized sheet iron. One end of each cylinder was fitted with a removable lid. The other end was closed. The seams were all soldered. The tanks were numbered from I to 4. The interiors of the tanks were brushcoated with raw linseed oil, soya bean oil, tung oil, and menhaden oil, respectively. The tanks were weighed previous to and subsequent to the application of the oil, in order to determine the amount of oil applied. The tanks were individually connected up to a train of three Woulff bottles, the first of which contained 66 sulfuric acid, the second and third containing a saturated solution of barium hydrate. Vacuum was applied
v01. 6 , N O .
2
common to each tank. The discolored sulfuric acid from each test had an acrid odor. The bottles containing barium carbonate had an odor suggestive of aldehydes. RESULTS: These tests indicate that the phenomenon of oxygen absorption which takes place when oils are spread in thin layers and exposed to the air, is accompanied by the evolution of considerable amounts of organic substances. Large quantities of carbon dioxide are simultaneously evolved. EXPERIMEKT 11.-A series of paints was prepared from those opaque white pigments which are most widely used in the manufacture of exterior and interior paints (basic carbonate-white lead, basic sulfate-white lead, zinc oxide, and lithopone). The oil used was raw linseed oil. No turpentine or drier was added. The lead pigments were ground to a thick paste with I O per cent of oil. The zinc pigments were ground to a paste with 15 per cent of oil. Oil in the proportion of about 7 gals. to the cwt. of paste was then added to each paint, the quantity of oil added in each instance being sufficient to make paints containing approximately 60 per cent pigment and 40 per cent oil. Each of the four iron cylinders described in Experiment I was then cleaned and painted on the inside with one of the four paints.. An effort was made to spread the same amount of paint in each tank. After painting, the tops were placed upon the tanks and they were connected up to Woulff bottles containing various reagents as shown in Fig. I . Uniform vacuum was applied to the end of each apparatus, and a @-hour run was made. The air passing into the apparatus was scrubbed through a I O per cent solution of caustic soda and then passed over soda lime in order to remove the carbonic acid present. The glass tubes coming from the ends of the cans were bent as shown in the illustration, to hold back any particles of paint which might be carried over, although such occurrence seemed highly improbable and such precautions unnecessary. A part of each exit tube was heated with the flame of a Bunsen burner, in order to
FIG. I-APPARATTJS
FOR DETERMINING CHARACTEROF VAPORSFROX PAINTED SURFACES I-Solution KOH, 10 per cent 4-Heated Glass T u b e 5-Sulfuric Acid 66’ 2-Soda Lime 6, 7-Barium Hydrate Solution 3-Metal Cylinder Painted on Inside
to the end bottle. The air entering the tank was scrubbed through a I O per cent solution of caustic soda, and then passed over soda lime to eliminate carbon dioxide. Soon after the tests were started, the sulfuric acid in the first bottle of each train became discolored. Within an hour the acid had assumed an amber color. The barium hydrate contained in the other bottles became opaque within a short time. At the end of a 2-day run, the sulfuric acid was dark red, and the barium hydrate solutions contained a dense white precipitate which proved to be barium carbonate. Each series of apparatus was disconnected and the coatings on the interior of the tanks examined. The amount of air passing through the tanks in z days was evidently insufficient to complete the oxidation of the oils which under normal conditions would have been quite dry in that time. The linseed oil was very soft and tacky. The soya bean oil was but slightly oxidized. The fish oil was somewhat tacky, but it had dried to a greater extent than the other two oils mentioned. The tung oil was very hard and dry. The smell emanating from the tanks was most unpleasant, being somewhat characteristic in each instance of the type of oil used. A certain nauseous smell, however, was
break up, if possible, any organic form of lead or zinc, which might be present in the vapors, since certain organic compounds of lead may not respond to tests for lead as made with ordinary reagents. I n every test the sulfuric acid contained in the bottle next to the tank was turned amber color within 5 minutes after the beginning of the test, thus showing that the drying paints were giving off considerable organic matter. After a $+hour run, the acid in each bottle was dark red. The amount of carbon dioxide evolved in each test was considerable. No quantitative determination of carbon dioxide was made in any case. At the end of the experiment, the cans were re-weighed t o determine the amount of oxygen absorbed. To the writer’s surprise, there was recorded a loss of weight in one test, and but slight, if any, gains in the other tests. The basic carbonate-white lead paint lost 2 per cent by weight. The basic sulfate-white lead paint and the zinc oxide paint neither gained nor lost, the weight of the films remaining constant. The lithopone paint showed less than I per cent gain. The bottles containing the sulfuric acid were removed from each train and the contents examined. Upon dilution with water,
F e b . , 1914
T H E J 0 l r R N A L 0 F IA‘D U S T RI A L A N D E XGI LVEE R I N G C H E M I S T R Y
the acid in the bottle, through which the fumes from the drying basic carbonate-white lead paint had been passed, became opaque. It was a t first thought that this cloudiness of the diluted acid might be due to the presence of lead sulfate, formed by the absorption of volatile lead compounds eliminated by the drying paint. Alcohol was added to a portion of the liquid. It immediately became clear, thus indicating the absence of lead X very thorough examination of the liquid was then made, and not a trace of lead was found. The sulfuric acid through which the vapors from the other paints were passed, was also examined. No metallic compounds were found. The experiments were repeated, the only refinement being that of introducing in front of the sulfuric acid bottles in the trains connected to the lead-painted cylinders, a bottle containing strips of filter paper saturated with sodium sulfide solution. The papers were not darkened in either case, thus giving further indication of the absence of lead compounds. I n another experiment, one of the cylinders was painted with basic carbonate-white lead paint and the gases evolved were passed through a heated tube, finally being drawn through a 2 per cent solution of nitric acid. The test was run for forty-eight hours. The acid was evaporated on a steam bath. The residue was taken up with dilute acetic acid and a few drops of water. It
lead paints each required about IOO cc. permanganate solution. The acids in the trains connected to the cylinders painted with zinc paints required from 19 to 39 cc. of permanganate, that connected to the lithopone cylinder requiring the least amount. The solutions of acid thus oxidized were transferred to separatory flasks and shaken with ether. The ether solutions were thoroughly washed with water and then evaporated. In each instance a dark substance which had the appearance of heavy oil was left as a residue. This substance was found to be soluble in alcohol, in which solvent very acid reactions were given. No attempt was made to identify the acids present. Their complex nature would make such determination rather difficult, especially when working on small quantities. RESULTS: I . The above experiments indicate that the vapors from drying paints contain acids of a water-soluble nature. These acids apparently contain formic acid. The amount of such acid evolved may be influenced by the type of pigt,nent present in the paint. The basic pigments are apparently more active than the neutral or inert pigments. 2 . Organic acids of a fatty or aromatic nature are apparently evolved from drying paints. The amount evolved may bear some direct relation to the pigment present in the paints. The basic pigments apparently are most active in this respect.
FIG. 11-APPARATUS FOR DETERMINATION OF COz 1-Solution KOH, 10 per cent 2 , 14-Iodic acid in t u b e ; Soya Oil Bath 3, 4, 15. 16-1 per cent K I Solution 5-Soda Lime
was tested microscopically1 for lead after the addition of copper acetate and potassium nitrate. No response for lead was shown in the test. RESULTS: The results of these tests indicate that drying paints, containing zinc or lead pigments, do not emit volatile compounds of a metallic character. When spread as thin films, oil-pigment paints are capable of evolving considerable amounts of organic substances without showing any material increase in their respective weights. EXPERIMEXT 111.-Experiment I1 was repeated after cleaning the interior of the tanks and applying fresh coats of paint. The first Woulff bottle in each train contained distilled water. The second bottle contained 66’ sulfuric acid. After a @-hour run, the contents of the first bottle in each train were examined. The water in each instance was acid in reaction. There were required for neutralization from I cc. to 14 cc. of N/IO KOH. The water in the bottle connected to the cylinder painted with lithopone showed the lowest amount of acid, while the water connected to the cylinder painted with basic carbonatewhite lead showed the largest percentage of acid. The presence of carbon dioxide in the water may partially account for the acidity of these tests. A portion of the neutralized acid was tested qualitatively for the presence of aldehydes. Small amounts of aldehydes were found present. Formates were also found present. The sulfuric acid in each of the four bottles was diluted with water and titrated with N / I O potassium permanganate to determine the amount of reducing substances present. The acids in the trains connected to the cylinders painted with white Page 167, “Lead Poisoning and Lead Absorption,” Legge and Goadby. Longmans, Green & Co., Publishers.
93
AND
CO IX VAPORSFROM PAINTED SURFACES 6,i-Bottles Painted on Inside 8-Fuming Sulfuric Acid 9-Distilled Water 10-13, 1 7 , 18-Barium Hydrate Solution
T h e aldehydic reducing substances a n d t h e acids which a r e evolved f r o m p a i n t s are, n o d o u b t , responsible for t h e odors which a r e coincident t o t h e drying of p a i n t s . I n t h e writer’s opinion, however, t h e r e are also evolved s u b s t a n c e s of a more poisonous n a t u r e . I n a s m u c h a s large percentages of carbon dioxide are formed, it is a t least possible t h a t carbon monoxide m a y also be produced. T h e following experiments were designed t o d e t e r m i n e whether t h i s gas is really formed EXPERIMENT 1V.-After many attempts to devise a suitable apparatus in which to determine the percentage of carbon dioxide or carbon monoxide which might be evolved by drying paints, the apparatus shown in Fig. I1 was found to be most satisfactory for the purpose. The first experiment made with this apparatus was conducted upon raw linseed oil. The interiors of two carefully weighed glass botdes, each having a capacity of one gallon, were coated with linseed oil. The oil was poured into each bottle and allowed to flow over the entire area of the interior, this being accomplished by revolving the bottle. After draining out the superfluous oil, the bottles were re-weighed to determine the amount of oil used for the test. Cork stoppers carrying glass air-tubes, were then inserted. The stoppers were thickly coated with paraffin to make them air-tight. The apparatus was connected up as shown in Fig. 11. Vacuum was applied a t one end. As the purpose of the experiment was to determine the presence and amount of carbon dioxide or carbon monoxide in the vapors from the oil, the air entering the bottles was first freed of its content of carbon dioxide and carbon monoxide. This was accomplished by first
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T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERIiVG C H E M I S T R Y
scrubbing i t through a solution of caustic soda in order to remove the carbon dioxide. The air was then run through a U-tube containing iodine pentoxide heated in a bath of soya oil to 150' C. a t which temperature carbon monoxide is oxidized to carbon dioxide.' The iodine liberated was absorbed in a I per cent solution of potassium iodide and the carbon dioxide formed was taken up by the caustic soda and soda lime in the subsequent train of apparatus. After the tests had been running for 15 minutes, the fuming sulfuric acid in bottle 8 was turned amber color, showing that organic substances evolved by the oil were being absorbed. The absorption of these organic vapors by the sulfuric acid prevented such vapors from interfering with the subsequent train of liquids in which the percentage of carbon dioxide and carbon monoxide were to be determined. Bottle IO containing saturated barium hydrate, the strength of which was determined by titration, showed a slight precipitate of barium carbonate at the end bf the first Io-minute run. At the end of a 5-hour run, bottles 10-1 I and 12 showed quite a noticeable deposit of barium carbonate. Bottle 15, containing potassium iodide, did not change color until the tests had been under way for over an hour. At that period the reagent became slightly yellow, showing that some iodine had been carried over into this bottle, thus indicating the presence of carbon monoxide in the vapor. The barium hydrate in bottle 1 7 at the same time became cloudy, showing that traces of carbon monoxide which had been evolved, had been oxidized and absorbed as carbon dioxide. The percentage of carbon monoxide evolved by the drying oil in five hours was determined by titrating the barium hydrate contained in bottles I O to 13 with N / I Ooxalic acid, using phenolphthalein as an indicator. The titration was made direct. The amount of carbon dioxiGe found present was 0.016 per cent. The amount of carbon monoxide was not measurable, although i t was shown to be present in traces. RESULTS: This experiment indicates that linseed oil in drying gives off traces of carbon monoxide. EXPERIMENT V.-Experiment IV was repeated, coating the interior of the bottles in this case with basic carbonate-white lead paint in place of raw linseed oil. The test was run for five hours. The amount of carbon dioxide produced in that time was 0.0305 per cent. The carbon monoxide evolved amounted to 0.006 per cent. The experiment was made with basic sulfatewhite lead paint in place of basic carbonate-white lead. The experiment was accidentally interrupted. The experiment was again repeated, using zinc oxide paint in place of the white lead paint. The amount of carbon dioxide evolved was 0.0292 per cent. The amount of carbon monoxide evolved was 0.0039 per cent. The experiment was again repeated, using lithopone paint in place of the zinc oxide paint. The amount of carbon dioxide evolved was 0.022 per cent. A mere trace of carbon monoxide was found. Experiment V was repeated with a basic carbonate-white lead paint. The first bottle leading from the painted bottles contained fuming sulfuric acid to intercept and collect the organic vapors. The second bottle contained water. The third bottle contained alkaline bisulfite solution to collect any traces of aldehydes which, if evolved by the paint, might possibly escape absorption by the sulfuric acid. The fourth and fifth bottles contained water and caustic soda solutions, respectively, the latter to collect the carbon dioxide or phenols evolved. The vapors passing from the last bottle were passed through a U-tube containing small lumps of caustic potash. The LT-tube was immersed in hot soya oil. At the end of a 5-hour test, the U-tube was removed from the hot oil and the lumps of caustic potash removed and examined for the presence of formates which, 1 "Method Used for Examination of Tunnel Gas," b y D r A. Sydell, Hygienic Laboratory, Washington, D. C.
Vol. 6, No.
2
if present, would indicate that absorption of carbon monoxide had occurred. After dissolving the potassium hydrate in water, making acid with tartaric acid and distilling over barium carbonate suspended in water, the filtrate from the barium carbonate was treated with a small percentage of bichloride of mercury. After the solution had stood over night, a very faint precipitate of calomel was observed, indicating the presence of carbon monoxide. RESULTS: These experiments would tend to show that the highly basic pigments stimulate the evolution of organic substances from linseed oil paints, especially influencing the amount of carbon dioxide and carbon monoxide evolved. T h e a m o u n t of air e n t e r i n g t h e p a i n t e d b o t t l e in a 5-hour r u n w a s insufficient t o c a u s e any m a r k e d oxidat i o n . T h i s explains w h y s u c h s m a l l a m o u n t s of c a r b o n dioxide and c a r b o n monoxide were o b t a i n e d . The extremely small quantities present made t h e analytical d e t e r m i n a t i o n s a m a t t e r of g r e a t care. T e s t s e x t e n d i n g over a g r e a t e r period s h o u l d b e made, i n o r d e r t o s u b s t a n t i a t e t h e figures p r e s e n t e d . T h e writer is designi n g a n o t h e r t y p e of a p p a r a t u s in which i t is h o p e d more accurate determinations m a y b e made. EXPERIMENT VI.-In this experiment a portion of lithopone paint was reduced with 15 per cent of turpentine and then applied to the interior of the bottles. At the end of three hours, the percentage of carbon dioxide evolved was 0.04, while the percentage of carbon monoxide was 0.003. This result may be due to the oxidation of the turpentine. RESULTS : Turpentine apparently accelerates the reactions which are responsible for the formation of volatile products from drying oils. The oxidative properties of the turpentine are probably responsible for this result. G E N E R A L DISCUSSION O F RESULTS
T h e results o b t a i n e d i n E x p e r i m e n t 11, in which t h e p a i n t films s h o w e d b u t slight if a n y increase of weight a t t h e e n d of the t e s t s , a r e interesting. T h e y may b e partially accounted for b y assuming t h a t t h e amount of a i r passed t h r o u g h t h e t a n k s i n 48 h o u r s w a s v e r y small. It will b e well at t h i s p o i n t t o discuss t h e exp e r i m e n t s o n linseed oil a n d oil-pigment p a i n t s , as m a d e b y Sabin.' H e describes a series of t e s t s i n which v a r i o u s p a i n t s were applied t o s m a l l glass p l a t e s , t h e increase i n weight s h o w n by t h e p a i n t s being recorded at different periods. A t t h e e n d of 7 d a y s , r a w linseed oil s h o w e d a g a i n in weight of 18 p e r c e n t , while w h i t e l e a d p a i n t s h o w e d a g a i n of a p p r o x i m a t e l y I j per cent. T h e writer carried o u t a similar series of t e s t s with a s e t of p a i n t s m a d e u p w i t h 60 p e r c e n t of p i g m e n t a n d 40 p e r c e n t of r a w l i n s e e d ~ o i l . T h e g a i n i n weight of t h e films at t h e e n d of 7 d a y s w a s a s follows: Per cent Linseed oil, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Corraded white lead. . . . . . . . . . . . . . . . . . . . . . . Sublimed white lead ........... Zinc oxide.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lithopone. . . . . . . . . . . ..
14.0 6.4 7.1 5.4
5.9
T h e s e tests i n d i c a t e t h a t oil-pigment p a i n t s d o n o t g a i n i n weight t o t h e s a m e e x t e n t as r a w linseed oil. Heretofore, h o w e v e r , i n v e s t i g a t o r s h a v e n o t g i v e n consideration t o t h e possibility t h a t p i g m e n t s m a y s t i m u l a t e n o t o n l y t h o s e processes which cause t h e oil t o increase i n weight t h r o u g h t h e a b s o r p t i o n of oxygen, 1
THISJOURXAL, 8 , 84.
Feb., I914
T H E J O r R S A L O F I S D I ’ S T R I A L A S D E*VGI-VEERI*VG C H E M I S T R Y
b u t also t h o s e processes a n d reactions which cause t h e oil t o eliminate r o l a t i l e s u b s t a n c e s , which m i g h t det r a c t materially f r o m t h e weight of t h e p a i n t . I n t h i s connection i t is of i n t e r e s t t o cite t h e t e s t s of Olsen a n d R a t n e r ’ u p o n t h e d r y i n g of linseed oil. T h e y record a gain i n weight of 18 p e r c e n t at t h e e n d of approxim a t e l y I O weeks. T h e y also showed t h e elimination of a p p r o x i m a t e l y j p e r c e n t of c a r b o n dioxide a n d ~j per cent of w a t e r . SUMMARY O F CONCLUSIOXS
I. W h e n linseed oil o r similar d r y i n g oils a r e s p r e a d in t h i n layers, t h e a b s o r p t i o n of oxygen which t a k e s place is accompanied b y t h e evolution of considerable a m o u n t s of c a r b o n dioxide a n d organic substances. C a r b o n monoxide is also evolved i n small a m o u n t . 11. Oil p a i n t s containing l e a d or zinc pigments d o n o t e m i t volatile c o m p o u n d s of a metallic n a t u r e . 111. D r y i n g p a i n t s evolve water-soluble acid s u b s t a n c e s such a s formic acid, a s well a s acid s u b s t a n c e s which a r e a p p a r e n t l y of a f a t t y n a t u r e . C a r b o n dioxide a n d c a r b o n monoxide a r e also p r e s e n t i n t h e v a p o r s f r o m t h e d r y i n g p a i n t . T h e t y p e of p i g m e n t used i n t h e p a i n t m a y directly affect t h e a m o u n t a n d c h a r a c t e r of t h e volatile s u b s t a n c e s p r o d u c e d . Basic p i g m e n t s a p p a r e n t l y s t i m u l a t e t h e evolution of such products. IT’. Aldehydic s u b s t a n c e s a r e present i n t h e v a p o r s f r o m d r y i n g oil p a i n t s . T h e s e s u b s t a n c e s p r o b a b l y h a r e a m a r k e d bactericidal effect u p o n pathogenic b a c t e r i a a n d would t h u s a c c o u n t for t h e s a n i t a r y value ascribed t o oil-pigment p a i n t s . T h e writer desires t o t h a n k H. C . F u l l e r , L . G. C a r mick a n d t h e staff of T h e I n s t i t u t e of I n d u s t r i a l R e sea:ch f o r t h e i r assistance i n carrying o u t t h e a b o v e experiments. RESE~RCH WASHINGTOS
I N S T I T U T E OF INDUSTRIAL
METALLOGRAPHY AS-APPLIED TO INSPECTION By WIRT TASSIN
Received December 11, 1913
T h e s u d d e n failure of engineering s t r u c t u r e s of m e t a l . t h e s t a t i c physical t e s t s of which, before use, pointed t o t h e good q u a l i t y of t h e materials. is well k n o w n . S u c h failures h a r e usually been a t t r i b u t e d t o a socalled deterioration k n o w n as “ f a t i g u e . ” W h e t h e r or n o t r e p e a t e d stresses below t h e elastic limit of t h e m e t a l can set u p such a deterioration m a y be questioned. One f a c t h a s however been p r o v e n bey o n d all question, a n d t h a t is t h a t i n a n y m e t a l t h e r e a r e a l w a y s present c e r t a i n s t r u c t u r a l conditions, t h e i n fluence of which a r e e i t h e r favorable or unfavorable t o “fatigue.” T h e c h a r a c t e r of these s t r u c t u r a l conditions is indic a t e d i n p a r t only, a n d t h e n o f t e n b y c h a n c e , b y t h e s t a t i c a n d d y n a m i c tests. I t m a y , however, be completely revealed b y metallographic m e t h o d s , t h a t is, b y t h e s t u d y of t h e s t r u c t u r e of t h e m e t a l as seen o n t h e e t c h e d surface u n d e r t h e microscope. T h e possibilities of metallographic m e t h o d s as a n a d d i t i o n a l safeguard t o d e t e r m i n e q u a l i t y h a v e been 1
J S C. I , 31, 9 3 ; (1912).
95
recognized, b u t t h e i r usefulness h a s been limited b y t h e lack of p r o t a b i l i t y in t h e , appliances necessary for t h e i r use. T h i s h a s m a d e i t difficult, if n o t impossible, t o s t u d y t h e forging, t h e casting or t h e b a r as a whole, with t h e result t h a t t h e metallographic field h a s been limited t o t h e e x a m i n a t i o n of more or less small specimens c u t f r o m t h e piece a n d which. like t h e b a r used for t h e machine t e s t s , m a y or m a y not be representative of t h e whole. It is t h e purpose of t h i s p a p e r t o describe a complete metallographic outfit which is p o r t a b l e a n d m a y be used either in t h e mill o r t h e l a b o r a t o r y a n d is serriceable for t h e s t u d y of t h e forging, t h e b a r or t h e casting a s a whole; t o give c e r t a i n t y p e s of s t r u c t u r e f o u n d i n t h e ferrous m e t a l s ; t o give a list of certain probable causes for failure a n d t o outline a scheme for their detection a n d t h u s s u p p l e m e n t o t h e r m e t h o d s of t e s t i n g . THE APPARATUS
T h e a p p a r a t u s i consists of a microscope, illuminating device a n d a c a m e r a , all self-contained. Fig. I , .I. B a n d
C. T h e microscope, Fig. 2 , consists of a barrel, b , a n d a d r a w - t u b e , d , m o u n t e d on a h a n d l e a r m provided with a coarse a n d a fine a d j u s t m e n t . A t t a c h e d t o t h e barrel is a shoulder, c, which holds a r o d , Y , controlled b y a set screw. T h e base of t h i s r o d rests o n t h e pinion h e a d of t h e h a n d l e - a r m a n d when lockcd m-ith t h e s e t s c r e n p r e v e n t s t h e coarse a d j u s t m e n t f r o m o v e r r u n ning when using t h e c a m e r a . T h e whole is carried o n a base which is t h e s t a g e . T h r o u g h t h e center of t h e s t a g e is a 1-inch circular opening which affords free space for t h e objective when examining large masses below it. Leveling screws a r e provided, one i n e a c h of t h e f o u r corners of t h e s t a g e , which p e r m i t t h e a d j u s t m e n t of t h e microscope perpendicular t o nearly a n y surface. T h e illuminating device consists of an a r m . a , in Fig. 2 , which locks i n t o t h e microscope barrel b y means of a t h r e a d e d collar. T h e a r m serves t o c a r r y t h e condensing a r r a n g e m e n t m a d e up of a telescope t u b e , t t , which carries t h e lenses. T h e t u b e is m o u n t e d in a sleeve, y, provided with a s e t - s c r e x t o lock i t i n a n y position. A h a n g e r , h , f r o m t h e a r m is a t t a c h e d t o t h i s sleeve b y m e a n s of a t r u n n i o n controlled b y a set-screw which p e r m i t s t h e t u b e as a whole t o be t i l t e d a t a n y angle. -4 vertical a d j u s t m e n t is provided for b y a set-screw a t t h e o u t e r e x t r e m i t y of t h e a r m . T h e r e a r of t h e telescope t u b e carries a shield, X X , pro\-ided with clips t o hold t h e source of light when electricity is used a n d is s l o t t e d t o hold a rod a n d a movable l a m p carrier when gas is used. T h e source of light m a y be a n acetylene j e t or a n electric l a m p . W h e n acetylene is used t h e gas m a y be o b t a i n e d f r o m a generator or f r o m a prestolite t a n k . The supp o r t for t h e l a m p is a rod which locks i n t o t h e slot in t h e shield of t h e illuminator. On t h e rod is placed t h e movable carrier for t h e source of l i g h t , see B , Fig. I . T h e n electricity is used t h e l a m p is carried i n a socket fixed in an insulated m e t a l hood a n d held i n 13Ianufactured by Bausch and Lomb, Rochester, K Y
