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T H E JOCRYSL OF INDCSTRLAI, A N D ESGINEERING CHEMISTRY
pected f r o m the use of a plastic or solid mass of cement embedded in inoculated agar in order t o show t h e germicidal properties.’ Plate I is a photograph of a Petri dish containing agar inoculated with saliva upon which two mixes of plastic masses of cement were placed. T h e plate was incubated for 48 hours. The upper mix of cement is Caulk’s Crown & Bridge & Gold Inlay Cement and t h e lower is Caulk’s Crown & Bridge & Gold Inlay Cement a n d Caulk’s Copr-Zinc (four parts of the former t o one p a r t of the latter, b y weight). Colonies of bacteria are seen over t h e entire plate. There is a sterile area around each cement mix. t h e actual meawrement on t h e original plate showing sterility within the radius of from 6 t o 8 m m . in both cases. It would h a r e been impossible t o specify t h e comparative germicidal properties of these two cements from t h i s test, since it failed t o show a n y marked difference in t h e germicidal power. Reference t o the photographs shown in Series 7 of the experimental p a r t of this paper plainly shows t h a t t h e same materials vary widely in germicidal power. Plate 2 is a photograph of a Petri dish containing agar inoculated with saliva into which t n o solid cylinders of cement were inserted. T h e photograph shows the bacterial colonies t o approach t h e cement mass much more closely t h a n in t h e case of the plastic mass. This is exactly what one would expect, owing t o t h e insolubility of t h e set cement as compared with t h e solubility of t h e unset or plastic mass. T h e upper mix of cement in this plate is Caulk’s Crown & Bridge & Gold Inlay Cement, a n d t h e lower is Caulk’s Crown & Bridge & Gold I n l a y Cement a n d Caulk’s CoprZinc (four parts of t h e former t o one part of the latter, b y weight). Here again i t would have been impossible t o state whether one cement was more germicidal t h a n t h e other, since reference t o t h e photographs shown in Series 7 of the experimental part of this paper plainly shows these two materials t o vary widely in germicidal power. SL31314RI
Dental cements known as copper cements ” vary Iv-idely in chemical composition. T h e several types sold t o t h e dental profession are at present described almost entirely by t h e color of t h e povider, and include red. white, black, and varicolored cements. T h e color of these cements is largely due t o t h e compounds of copper used in their production, although pigments a r e used t o improve t h e color. Such additions m a y be considered t o be legitimate if t h e cement s h o n s t h e requisite germicidal power. Cuprous oxide, cupric oxide, a n d zinc oxide have marked germicidal properties. T h e addition of cuprous oxide, cupric phosphate. a n d cuprous Iodide, t o zinc oxide, enhances t h e bactericidal properties of t h e zinc oxide. T h e addition of varying amounts of cuprous iodide t o a “copper-free” dental cement shows t h a t t h e germicidal efficiency is increased in proportion t o t h e q u a n t i t y added. T h e addition of I per cent of cuprous 1 This
method is in quite common use for testing dental cements.
T‘ol. 7 , NO. 3
iodide t o a dental cement increases considerably t h e germicidal efficiency. Commercial “copper cements” show wide differences in germicidal eEciency, t h e color of t h e cement having no relation t o its bactericidal properties. Tests for germicidal properties of dental cements in “plastic” or “set ” condition are unsatisfactory if such mixes are placed in inoculated bouillon or agar-. agar, ov-ing t o t h e difference in chemical composition of the nutrient culture media and the saliva. T’isual. tests for inhibition of bacterial growth are purely qualitative tests and fail t o demonstrate the comparative germicidal efficiency of these materials. T h e comparative germicidal efficiency of “copper cements ” can be ascertained only b y methods which determine t h e number of living organisms killed on exposure t o t h e cement under fixed conditions. Much misleading information has been circulated in regard t o t h e germicidal properties of “copper cements.” This has been based upon ignorance of t h e manufacturer, or upon pseudo-scientific or in.. conclusive tests. CoIYcLuSIo~s
T h e germicidal efficiency of a dental cement is merely one of the properties which are of importance. M a n y other physical properties such as resistance t o saliva, hardness, crushing strength, constancy of volume, etc., are also of importance. T h e relation of t h e germicidal efficiency t o these other properties is being investigated in this laboratory, and t h e results will be published in future papers. Many of t h e bacteriological tests contained in this paper were conducted while t h e author was still associated with t h e Lederle Laboratories, a s Assistant Director of t h e Department of Chemistry. The author desires t o acknowledge his indebtedness to Dr. H. D. Pease, Director of t h e Department of Bacteriology of t h e Lederle Laboratories, and t o his assistants, for having conducted many of t h e tests. LABORATORIES OF THEL. D.
CAULK COMPANY
MILFORD, D E L A W A R E
DRYINGTPROPERTIES OF LINSEED OIL TREATED WITH COBALT, LEAD AND MANGANESE ELAEOSTEARATES’ By LOUISE Wise
A N D ROBERT A. , D U K C A S Received December 15, 1914
Since the manganese, lead and cobalt linoleates have been successfully used in the preparation of siccatives in t h e manufacture of boiled oil, i t seemed of interest t o a t t e m p t t h e preparation of the corresponding salts of a-elaeostearic acid, a probable isomer of linolic acid,2 a n d t o s t u d y t h e drying properties of linseed oil which had been treated with these soaps. a-Elaeostearic acid, which occurs as t h e triglyceride in Chinese wood oil, gives t h e oil its characteristic properties of gradually crystallizing on exposure t o light3 and of gelatinizing when heated to about zoo’ C. The free acid is a n unstable, crystalline compound, 1 This is a brief abstract of the thesis submitted by Robert A. Duncan in partial fulfilment of ,the requirements for the degree of M.A. in the graduate school of the University of Missouri. f Kametaka, J. Chem. SOC., 83, 1042. 3 Cf. Ware and Schumann, THISJOURSAL, 6 (1914), 806.
Mar., 191 j
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
m. p. about 48 O C., resinifying rapidly in air a n d changing readily into its p-isomer, m. p. 71 ', when its ethereal or alcoholic solutions are exposed t o light. Since some of t h e derivatives of elaeostearic acid also readily undergo change on exposure t o light a n d air, due precautions were taken in the preparation of t h e metallic elaeostearates. One hundred grams of commercial Chinese wood oil (with a saponification number of 190) were heated with about IOO cc. of 2 0 per cent hour, in a darkened flask under alcoholic KOH for a reflux condenser, a slow stream of hydrogen being conducted through t h e reaction mixture during t h e saponification. On cooling, t h e potassium soap' separated in t h e form of radiating clusters of white needles. The product was recrystallized five times from 90 per cent alcohol, a n d dried in a darkened Drexel bottle at 100' C., i n a current of dry hydrogen, or i n vacuo. All filtrations were made b y suction a n d solutions were never exposed t o direct sunlight. The dried, powdered soap, when decomposed by acids yielded a-elaeostearic acid (melting a t 44' C.). I n spite of all precautions taken t h e potassium soap was never obtained in. absolutely pure state. The lead elaeostearate was prepared b y treating a clear, aqueous solution of t h e potassium soap with a n aqueous lead acetate solution, rapidly filtering t h e resulting i'nsoluble precipitate, washing thoroughly vacuo, over with water, a n d drying t h e product fused CaC12. The manganous a n d cobaltous soaps were prepared b y very similar methods using MnC12 and, CoC12, respectively. The metallic soaps all undergo marked decomposition at 50-60" C. a n d resinify rapidly on exposure t o air. The dry lead soap is a white powder,2 containing 28 per cent of lead whereas the theoretical percentage lead in lead elaeostearate is 2 7 . 0 j . The manganese soap is also a nearly white powder containing 9.96 per cent manganese, t h e calculated percentage i n manganous elaeostearate being 8.97 per cent. The cobalt soap, when first precipitated from its solution, formed a pale pink curd which rapidly darkened t o a rich purple. The dried soap, which was apparently not homogeneous, contained 9.05 per cent cobalt, whereas t h e theory for cobaltous elaeostearate requires 9.56 per cent. All of these heavy metal soaps, when dissolved in linseed oil, cause a marked increase in t h e rate of drying of t h e oil. I n order t o obtain comparative data in our drying tests, four Io-gram samples of a good commercial'linseed oil were placed in test tubes and treated as indicated below: Sample
B... . . , . . . . , , . . . . . . . .
0.2957 0.3695 0.2990 0.1072
Mixed with g. manganese elaeostearate g. lead elaeostearate g. cobalt elaeostearate g. litharge
Both B a n d D contained 0.1 g. (or I per cent) lead whereas A contained 0.926 j g. manganese a n d C contained 0.0287 g. cobalt. The mixtures contained equivalent amounts of t h e "drier." since in each case t h e ratio equivalent weight of metal : weight of metal i l z weight of drier t a k e n was constant. These mixtures together Cf. Cloez, Compt. rend., 83, 934. Cloez, LOC.cit., who prepared this soap. 27.74 per cent lead.
* Cf.
with a control E (which contained simply I O g. of linseed oil) were then heated'for 6 hours in a n electric oven a t 3501375' F., a n d shaken a t intervals during t h e period of heating. The oils were allowed t o cool a n d settle, a n d were later used in the drying tests. I n carrying out these tests, glass plates of uniform size weighing about 2 5 g. each were used. An exact area of 42.9 sq. cm. was marked off on each plate b y means of a glass cutter and t h e plates were carefully cleansed, dried a n d weighed t o t h e nearest 0.1 milligram. Thin films of oil taken from Samples A , B , C, D a n d E were then spread as uniformly a n d as rapidly as possible over the exact areas outlined on t h e plates. The latter were again weighed without delay a n d laid horizontally in a ventilated, dust-free glass cabinet, which was exposed t o diffused daylight. At frequent intervals (every'few hours during t h e first few days) t h e plates were accurately and rapidly weighed a n d replaced in t h e cabinet, t h e room temperature at t h e time of weighing being invariably recorded. The j drying tests, which were run in duplicate, extended over a period of nearly 450 hours. Since, in these tests, t h e oil films were by no means identical in thickness and in order t o assure ourselves t h a t these differences did not materially affect t h e rate of drying or gain in weight,l we undertook a similar series of drying tests (using a boiled oil containing I per cent lead, as litharge) in which oil films covered identical areas b u t varied considerably in thickness. Our results, Table I , indicate t h a t during t h e drying process the percentage gain in weight at t h e end of definite time intervals, is practically independent of the film thickness. TABLBI-EBFECT OF FILMTHICKNESS ON RATEOF DRYING Temp. PER GAIN CENT IN Time of a t time of WEIGHTIN GRAMSOF FxLnr drying weighing A_----WEIGHT OF FILM Hours C. I I1 I11 I I1 I11 n 23 0.0 0.0 0 . 0 24 1.5 1 . 8 2.1 2.0 5.5 4 . 6 5.4 5.0 21.5 21 8 . 7 7 . 8 7.5 8.5 21 11.5 1 1 . 9 1 1 . 4 11.3 23 1 5 . 6 15.9 1 5 . 8 23 27 25 16.1 1 5 . 3 15.8 23 30 15.2 1 5 . 0 1 5 . 2 19 .. 35.5 13.9 1 4 . 4 1 4 . 4 A7 22 1 3 . 5 14.1 14.2 22 14.8 1 4 . 4 14.6 50 59 25 14.8 1 5 . 0 1 4 . 8 70.5 25 13.9 1 3 . 8 1 4 . 0 25 13.9 1 3 . 8 1 4 . 0 79 25 84 13.5 1 3 . 8 1 4 . 0 27 95.5 13.9 13.2 14.0 108 9 . 3 1 0 , s 11.8 Wa) 20 122 10.2 1 1 . 4 12.0 20 132.5 1 l . t 11.4 12.2 147.5 24 10.) 1 1 . 4 12.2 18 180 10.7 1 1 . 4 12.2 22 250 11.1 1 0 . 8 11.4 (a) A t the end of 108 hours, the sudden decrease in weight of the oil films may have been influenced b y the drop in temperature.
I n t h e accompanying graphs t h e abscissas represent t h e hours of drying, while t h e ordinates represent t h e percentage increase (or decrease) in t h e weight of oil film. In all cases smooth curves have been drawn, the two curves of each set representing t h e results of duplicate drying tests. I n t h e case of untreated oil, these duplicates do not check closely, whereas in t h e other cases t h e curves are very nearly coincident. Since Gardner2has shown t h a t a drying oil filmloseslarge 1
1
His analysis showed
203
This had been previously indicated by Lippert. 2. angew. Chem.,
iaw, p. 42. 2
THISJOURNAL, 6, 91.
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T H E JOL-RNAL OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
MANGANESE SOAP
CO6ALT
SOAP
Yol. 7 , No. 3
Mar., 1915
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amounts of carbon dioxide a n d traces of organic compounds,l soon after exposure t o air the weight2 of the film a t a n y stage of t h e drying process is dependent on the resultant of t h e gain due t o oxygen absorption a n d these losses. The drying process is a continuous one and there can be no definite point on a n y of t h e curves a t which this process may be termed complete. We are, however, inclined t o agree with Lippert t h a t the highest point on t h e curve may be advantageously used in judging the relative rates of drying. When this maximum is reached the film is tough and elastic, the surface may be termed “dry” a n d we are probably justified in saying t h a t the most rapidly drying oil film reaches its maximum weight in the shortest space of time. The curves indicate clearly t h a t the addition of the three elaeostearates greatly increases the rate of drying of linseed oil. The three sets of curves are quite similar a n d indicate very similar drying properties. The film containing the manganous soap probably dries most rapidly.3 I t s maximum gain in weight is t h e lowest of t h e series. The litharge a n d lead elaeostearate drying curves resemble each other very closely although the latter shows a somewhat greater .gain during t h e first stage of the drying process. The general similarity of these curves leads us t o the conclusion t h a t t h e drying action depended solely on the presence of the lead, a n d was quite independent of t h e nonmetallic radical in the drier. The cobalt soap-oil film has drying properties similar t o those of the oil film treated with lead soap, but loses more rapidly t h a n t h e latter after the maximum gain in weight has been reached. I n conclusion we beg t o t h a n k the Standard Varnish Works of Staten Island, Tu’. Y., for supplying the Chinese wood oil used in this work. CHEMICAL LABORATORY, UNIVERSITYOF MISSOURI COLUMBIA 1 Klein has very recently shown that Gardner’s results do not prove the presence of carbon monoxide in the vapors given off by drying linseed oil films. Cf. THISJOURNAL, 1, 99. 2 Cf. Sabin, I b i d . , 3, 81. * This point is more clearly indicated in an unpublished set of curves representing the results of drying tests with the same linseed oil treated with these soaps at 250-70’. The curves are somewhat steeper than those given herein.
20;
VANATIONS OF THE PHYSICAL CHARACTERISTICS OF A PETROLEUM RESIDUUM WITH INCREASING PERCENTAGES OF GRAHAMITE By H. ROSSBACHER Received November 23, 1914
I n the technology of asphaltic materials the fluxing
of asphaltites such as Grahamite a n d Gilsonite in asphaltic or semi-asphaltic petroleum residuum plays a very important r6le. It is well known t h a t the effect of increasing the proportion of the asphaltite is t o raise the melting point and lower t h e penetration of t h e product. The object of this paper is t o present a graphic representation of the alteration of the physical characteristics of a sample of Mexican residuum o n fluxing with it increasing percentages of Grahamite. DESCRIPTION OF E X P E R I M E N T S
Typical samples of Mexican residuum a n d Grahamite were taken (Table I ) ; the flux was weighed into a copper beaker of about 2 j 0 cc. capacity and heated t o 475-485’ F. a n d t h e finely powdered Grahamite was added with stirring. Stirring a n d heating a t t h e TABLEI-MATERIALSUSEDIN EXPERIMENTS GRAHAMITE MEXICAN RESIDUUM 1 ,0039 Sp. gr. 7 7 O F . . Sp. gr. 77’ F. 1.1822 78” ...... Per cent Shutte 77 F . None CSI insoluble.. Fixed carbon 53.77 0.31 per cent Ash CCh insoluble.. 1.17 8 8 O Be. naphtha insoluble.. 2 1 . 5 0 per cent CSz insoluble (hot) 0 . 8 3 Flash point.. 457a F . CClr cold 95.65 insoluble hot 74.75 Fire point.. 505 F. 8 8 O Be. /cold 99.46 naphtha Evaporation loss: 97.12 13.4 per cent insoluble hot 20 hours at 485O F . .
........... ............ ........... ........... ............. ..............
1
~
.......
above temperatures were continued until the solution was complete. About a n hour was the average time required, varying, of course, with the percentage of asphaltite t o be fluxed. Percentages of Grahamite from o t o 3 0 were used (Table 11), the coarseness of the product in t h e latter case indicating t h a t the limit of solubility was being approached. T h e “Ring a n d Ball” melting points noted in Table I1 a n d Fig. I were determined b y the method developed in t h e Chicago laboratory of the Barrett Manufacturing Company. T h e melted sample is poured into a brass cylinder 6/8 inch high, exterior diameter 13/16 in., interior diameter 3/4 in.: copper wire is soldered t o t h e cylinder for suspending it in t h e bath. When t h e sample has cooled t o room temperature i t is cut off level w i t h , t h e top of t h e cylinder a n d a brass ball
I
