The Weathering of Creosote H. E. GILLANDER,C. G. KIKG, University of Pittsburgh, E. 0. RHODESAND J. N. ROCHE, Koppers Products Company, Pittsburgh, Pa.
T
HE v a l u e of c o a l - t a r creosote as a wood pre-
fungus, exert a greatly increased inhibitory action towards the same f u n g u s w h e n p r e s e n t as mixtures of these same compounds. By working w i t h mixtures of t h e s e h y d r o c a r bons B a t e m a n was able t o show that the combined effect is the product of the percentage growths o b t a i n e d when each component is tested separately. This c o o r d i n a t i o n of action c o u p l e d with t8he e x t e n s i v e n u m b e r and v a r i e t y of compounds present in coal-tar creosote helps to explain its unusual fungicidal activity (6). T h e r e s u l t s of Bateman's work show that the fungicidal c o n s t i t u e n t s in creosote are made up of the group of hydroc a r b o n s d i s t i l l i n g below 270" C. and the tar acids and tar bases distilling above 270" C., also that the hydrocarbons which distill above 270" C., while not fungicidal, do possess pronounced inhibitory powers against fungus growth. Bateman has also shown that the toxicity of a creosote is a function of its percentage distilling below 270" C. This indicates that the group of hydrocarbons distilling below 270" C. comprises the essential fungicidal component of coal-tar creosote. Recent work by Schmitz and Buckman (12) on the higher boiling fractions of creosote points out the relatively small amounts of these materials necessary to exert marked toxic effects. For example, they have shown that one per cent of an oil, free of tar acids and tar bases, distilling between 285' and 350" C., inhibited the growth of Fornes annosus 95.6 per cent and the growth of Trainetes serialis 93.5 per cent. Studies leading to an evaluation of the permanence of creosotes have been reported by a number of investigators. Fredendoll ( 8 ) , Teesdale (15), von Schrenk and Kammerer (I,$), Curtin, Kline, and Thordarson ( 7 ) , and Ramage and Burd (11) have studied the evaporation of creosote from open pans and/or from wood blocks. Their work indicates that the loss of oil caused by evaporation is dependent upon the percentage of low-boiling materials in the original creosote. The last named authors also subjected impregnated wood blocks to the action of sea water. They report that losses in this case were smaller than those obtained in corresponding air evaporation tests and that the losses caused by sea water were confined entirely to the lower boiling fractions. Rhodes and Gardner ( I O ) , in a general study of the components of creosote, measured the vapor pressures of different fractions and showed that the presence of high-boiling materials reduces the vapor pressure of the more volatile constituents. Bateman (3) has developed an equation connecting the character of a creosote and its rate of evaporation. With this equation as the basis (4) he has formulated a relationship that considers (1)the character of the creosote, ( 2 ) the amount injected into wood, and (3) the preservative life afforded by
A machine is described in which small sapuood blocks evenly impregnated with creosote are exposed to continuous weathering cycles to allow the effects of weathering to be studied either as the results of individual factors or in the aggregate. T h e course of weathering is followed by removing a certain number of blocks at stated intervals and determining (1) their resistance to direct attack by f u n g i , ( 2 ) the percentage loss of oil, (3) toxicity of the extracted oil, and ( 4 ) the distillation range of the extracted oil. Data are gizten to show the degree of weathering brought about by the machine and the effect of various cycles. Toxicity-permanence interrelationships are deaeloped, and Ihe probable mechanics 0.f weathering of the oil in treated wood discussed.
servative is well known. Wood impregnated with creosote is r e n d e r e d i m m u n e to attack by fungi, marine borers, and termites for many y e a r s . The fact that it is so permanent has made d i f f i c u l t the study of changes and losses that are known to take place slowly in the creosote because of weathering. Up t o the p r e s e n t time the usual method for evaluating a creosote or for comparing one creosote with another has consisted in treating railroad ties or test fences with the different creosotes under test and observing their behavior over periods of ten to twentv-five vears or longer. Obvious& sucii a test is valuable and is the final criterion, but it should be supplemented by a laboratory method that will give comparable results in a short time. With this object in mind an apparatus and technic have been developed, and studies have been made of the factors involved in weathering, the relative importance of these factors, and the mechanism by which they act. The weathering of a creosoted material begins as soon as the timber has been impregnated and placed in service. As the weathering proceeds, the composition of the oil changes owing to a gradual loss of the lower boiling hydrocarbons, tar acids, and tar bases by evaporation and water leaching. Such changes in composition as these are accompanied by a decrease in the toxicity of the creosote. Loss of portions of the oil results likewise in a smaller amount of oil remaining t o protect the wood. The ability of a creosote t o resist such losses and to remain in the wood intact is a measure of its permanence. It is evident that these factorstoxicity and permanence-are interrelated, and that any estimation of the preservative value of a creosote--its service efficiency-must take into account both factors. While these facts have been recognized generally, research has been confined mostly to studies of the toxic action of creosote. The effects of weathering and, in particular, the relation between toxicity and permanence have not been as thoroughly investigated. The literature records an extensive amount of n ork on the toxic action of creosote. Bateman and co-workers (a)have shown that the characteristics of creosote that m w k it as a superior protective agent against fungus attack are not endowed upon it by specific compounds or even by certain groups of compounds, but that all the compounds and groups of compounds investigated are toxic towards fungi, the degree of toxicity being dependent upon the water solubility and molecular weights of the various compounds. It was found that the hydrocarbons distilling above 270" C., while their solubilities in water are so small that singly their saturated solutions exert only a moderate inhibitory action on a
creosote. lie lriis presented a graphical represetitation of this relationship. The application of tlrese various researches to our understanding of tlie actrial >\-eatlieringof creosote has been small. r. 1 he literature on toxicity, alttrougii it presents a fairly complete pictnre of tlie toxic principles of creosote, includes Sew data that r:onnect those principles with our understanding of permanence. The cunnection is iniportant Imause tlie toxicity factor of a creosote is not static but is continually changing, being dependent upon the changing composition of t.l,e oil in tltc wood ilie
F,Gu,%I':1.
WE,.rnliRTN . ,s
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OF
1h.r~ .AND A l a
IlI17,l.LATION R A r a E l i j P S K C&Nf
I1 270° C .
270 355' C .
Residue
.*:I 6
'30. X
19.Y
11.9
51.8 49 2
8.R 8 8
40 7
1'1.0 29.0 38.2 42.6 C2.9
% Il.ll
38.6 48.8 26.8
I8.R
4R.i
I'?.ClYlilS
(:oxrmuous mi) Am UIT~IOVPWnmn. One hundred test blocks, having an avoriige impregnation of 16.7 pounds uf oil per cubic fwt (2157.2 kg. per ciihic meter) Were used in this experintent. The water phase was omitted from the rveatliering le, and tlre air temperature in the hood was adjustcil to 67" C. by means OS an outside resistance so that the result,s conld be compared with tlw previous experiment. Blocks contaiiiing progressively wenthered oils were removed for anrilpis of the oils at tho end of 3, (i11, , and 15 wceks. Deternrinntions of tile degree of n.eat,tioriirg included calculation of the percentage loss of oil and the distillation ranges of the oils. These data are presented in Table 111.
V a ~ r a . r , c o N OF Iloou TEMIPEH.I~.URE. T o find the effects uf various hood temperatures on the rate at which oil was lost
from tho blocks, the heating units in three hoods were readiusted so tliat the air teninerntures in the hoods were 70". gob, and 110" C . It wa8 found tliat the acceleration in the riite of loss NILS proportional to the temperature differential and that the rise in tlie air teinperature of tlie iiood brought abont a proportional rise in tlre block surFacc ternperatnre. As stated previously, a hood air temperature of 90" C. corresponded t u a block surface temperature of (i2" to 63" C .
IN DUSTR IA L
February, 1934
E N G I N E E R 1 N G C H E R.I I S T R Y
I ND
CONTINUOUS \vArER .4ND AIR WITHOUT HEAT. Creosoteimpregnated blocks were subjected to the action of a continuous water phase on the weathering machine, the heaters in the hoods being disconnected. Air had little chance to act, since the blocks were covered with a water film even when not submerged. At the end of 6 weeks of weathering it was found that 52 per cent of the creosote had been lost. Using the method of calculation given previously, it was found that the total loss of oil (52 per cent) was made up of a 36 per cent loss due t o mechanical action and a 16 per cent loss due to the leaching or true weathering action of water. The loss of oil due to the leaching action of the water was confined almost entirely to the fraction distilling below 270" C.
EFFECTO F CONTINCOUS HEATAND -4IR HOURPER DAY
WITH \ y A T E R OVTE
The previous experiments showed that ii continuous water phase in the weathering cycle resulted in an excessive loss of oil due to the mechanical action of water. While the extent of this action was determinable, such a large loss of whole oil tended to obscure the results of truc. weathering. A water phase should be present in the weathering cycle, and yet the mechanical removal of oil should be prevented as far as possible. This condition could best be realized by making the water phase intermittent. Data on water absorption showed that the test blocks absorbed as much water during the first hour of an 8-hour test as they did during the following 7 hours. From this it was evident that but little increase in the rate of leaching would be gained by keeping water in the cycle for more than one hour a day and that reducing the period of the water phase would greatly reduce the amount of oil lost through mechanical action. On the basis of the studies made using the partial weathering cycles, the other factors in the cycle-that i4, the rate a t which the wheels revolved, the hood temperature, and the air delivery rate-appeared to be entirely satisfactory. Consequently a cycle consisting of those factors as they were, plus a water phase modified to the extent that it would be present in the cycle only one hour in twenty-four, would accomplish the weathering of the oil in a manner closely approximating actual service weathering. TABLE
Iv.
EFFECTOF WATER
WEATHERING PERIOD Weeks 0 1 3 5 9
Loss O F OIL
CONTIXUOUS
OXE HOURPER
HEAT h\D
,4IR
WITH
DAY
DISTILLATION R W G EI S P E R CEINT 0-270' C 270-355' C Residue
FUNGICID4L
CONCB
%
% 36.8 19.0 43.6 23.2 21.3 53.1 11.2 53.9 34.6 50.1 40.2 8.9 50.7 57.2 4R., 4.8 45.5 64.7 D~TA RECALCULITID TO SHOK G F ~ A M S REMAINING F R O l f 100 GRAMS O F 0.0 33.7
0.1 0.3
0.8 2.0 4.0
growing cultures of Lentinus lepideus gave negative results, showing that the amount and character of the oil remaining in the blocks was such that it was able completely to protect the wood. Figure 4 shows the blocks photographed at the end of 2 months of exposure. The exact concentrations, distillation ranges, and fungicidal powers of the oils present in the 5- and 9-week blocks are given in Table IT'. For purposes of comparison a control dish containing an untreated block that had been subjected to fungus attack for a like period is also shown in Fiqure 4. Attention is called to the high degree of weathering obtained, the large loss of material which distills between 270' and 355' C., the small loss of oil distilling above 355" C., the low fungicidal power of the oil at the end of 9 weeks of weathering, and the negligible loss due to the mechanical action of water. OCTDOOREATHE HE RING
O F TEST
BLOCKS
These tests were carried out so that comparisons could be made between the weathering brought about by different seasons of the year, as well as between weathering obtained under outdoor conditions, and that obtained by the use of the weathering machine. The blocks were weathered while hung from wires on the roof of a building. The winterweathered blocks had a r average initial impregnation of 15.0 pounds and the summer-weathered 16.5 pounds per cubic foot (240 and 264 kg. per cubic meter). The same oil was used as in previous experiments. The data for the test follow: DISTILLATION RANQEI N PERCENT
~~EITHERISG
SEASON
Winter Summer
iVinter Summer
PERIOD
Lo34 OF OIL C-270' C. 270-355O C. Reaidue
%
Weeks 11 9
19.8
44.4 47.1
.. ..
11 9
14.4
51.9 48.9
28.3 36.2
DATA RECALCULATED A S GRAMS REMAININQ FROM 100 GRAMSO F ORIGINALOIL 11.0 Z8.9 15.7 7.6
-5.9
19.2
The data shoTv that there was no great difference between winter and summer weathering with this creosote. Comparisons between the summer veathering and that obtained by the machine show that the machine produces a marked degree of acceleration and that it weathers the oil in the same way as did the outdoor conditions. The acceleration brought about by the machine can be noted by referring the loss of oil due to 9 weeks of summer weathering (47.1 per cent) to Figure 3 which shows that this loss took place on the machine in 16 days. Measurable quantities of material distilling between 270" and 355" C. were lost as,the result of outdoor weathering.
ORIGINAL OIL
Accordingly, the weathering cycle was arranged to include heat with the hood temperature a t 90" C. (block surface water one hour a day, and temperature a t 62" to 63" C.), moving air. The wheels were revolved at the usual speed, giving five cycles per hour. One hundred test blocks with an impregnation of 16.7 pounds of creosote per cubic foot (267.2 kg. per cubic meter) were used. Blocks containing the progressively \\-eathered oil were removed for analysis at the end of 1, 3, 5 , and 9 weeks. The percentage loss, the distillation range of the remaining oil, and the fungicidal power of the remaining oil for five periods during the ttlst are given in Table IV. Figure 3 shows the rate at which the oil was lost from the test blocks. Direct exposure tests of the weathered block5 to actively
181
OPEN-P-4N EVSPORITIOKT E S T S In this study of the evaporation of creosote from a free, liquid surface the purpose was to evaporate the oil to the point a t which the loss mould be equal to its percentage distilling to 270" C. and then to determine the composition of the residual oil. The evaporations were carried out in straight-sided dishes that afforded a constant oil-surface area. The dishes mere mounted on a slowly revolving and tilted platform that prevented the formation of suiface films of crystals. A slow stream of air from an electric fan passed over the oil surfaces. The results from four evaporations conducted a t different temperatures mere as follows : EVAPX, TIME Days 78 14 4
1
EVAPN. TEMP. O C .
25-28 56 67 90
LOSS
DISTN. R.ANGE OF R E ~ I D V OIL ~L
0-270° C.
270-355'
C.
Residue
70 45.4 44.5 45.4 45.4
0.4 1.5 1.2 1.5
64.5 64.0 64.2
..
:34.7 34.0 34.2
..
182
INDUSTRIAL AND ENGINEERING
The data are presented graphically in Figure 5. The results of these experiments indicated that within the limits of the fractionating accuracy of the apparatus practically all of the material distilling below 270" C. must leave before evaporation of material boiling above 270" can take place. I n order to learn whether such a phenomenon existed for the 235" C. point also, an evaporation was carried out a t room temperature to a loss equal to that point (27.4 per cent). Distillation of the residual oil showed 9.2 per cent
Y
€VAPORAT/ON
T/M€
/N
WCEnJ
FIGURE5. EFFECTOF TEMPERATURE ON RATEOF Loss CREOSOTE FROM A FREELIQUID SURFACE
OF
distilling to 235" C. and indicated that material distilling above 235" C. had evaporated along with material disfilling below 235" C. Further evaporation tests run to losses equal to the original amounts distilling to 300" and 350" C. showed less than 1.5 per cent distilling below these points in the residual oils. The results of these evaporation tests indicate that (1) evaporation of creosote occurs in such a manner that practically all of the material distilling below 270" must leave before evaporation of higher boiling material can occur, (2) evaporation of the higher boiling material takes place fractionally in a general sense, and (3) a great increase in the rate of evaporation is brought about by a moderate increase in temperature.
Vol. 26, No. 2
CHEMISTRY
broken down to the point where it failed to protect the wood against fungus attack as shown by the direct exposure tests, it had been heavily nreathered. The distillation data in Table IV show that 96 per cent of the 0" to 270" C. fraction and 56 per cent of the 270" to 355" fraction had been lost at the end of the 9-week period. The fungicidal power of the oil had become one-fortieth of the original. Figure 3 shows that the rate of loss of oil had become very small at the end of the 9 weeks of weathering, indicating that the oil had approached practically a constant composition. Apparently only slight additional changes in the characteristics of the oil could have been brought about by further weathering. The data from the final run may be used to show the interdependence of the permanence and toxicity factors of the creosote by means of a simple equation. This is possible because the weathering method gives exact data on the original impregnation, the percentage loss of oil, and the toxicity of the residual oil remaining in the wood. These data are correlated in an equation that gives the excess amount of creosote remaining in the wood (test blocks) as the ratio of the amount of creosote in the wood to the amount of creosote necessary to protect the wood; in other words, the equation tells whether or not the residual oil remaining in the wood is able to protect it against fungus attack: = per cent excess creosote
where A B C
= = =
original impregnation, kg. per cubic meter oil remainingin test blocks, % fungicidal concn. of residual oil (560 kg. is taken as the weight of one cubic meter of wood; 100 per cent water saturation is assumed for the wood.)
It can be seen that 100 per cent excess creosote represents the border line with this equation, for any smaller percentage means that there is not enough of the particular type of creosote in the wood to protect it. Calculation of the per cent of excess creosote for the initial and for the final test
DISCUSSION OF RESCLTS
The data show that the weathering machine is able to bring about the same changes in the characteristics of a creosote as would be expected to occur under service conditions. This follows, in part, because the various factors responsible for the weathering are regulated so that they are no more intense than those encountered in service. Further, since the oils are weathered while contained in wood, all contingent factors bearing on this point are involved in the method, and the results are capable of direct interpretation. A t the same time, the weathering method offers a high degree of acceleration; a 9-week weathering period brings about changes that are reached only after many years of actual service. The method allows the course of weathering to be followed, affording data on both permanence and toxicity for each test period during the run. These data are analytical in nature and cover the original composition of the creosote, the original impregnation of t,he wood, the percentage loss of creosote, the composition of the residual creosote, and the fungicidal power of that residual creosote. In addition, the machine furnishes standard weathered blocks that may be used for direct exposure tests against cultures of different fungi. The data for the final run are given in Table IV. Studies of the effects of the individual weathering factors in the other runs had shown what could be expected from each one, and t h e set-up for the final run was so adjusted that each factor had as extensive an effect as possible without interfering with the effects of the other factors. Although the creosote at the end of 9 weeks of weathering on this cycle was not
so000
40000
JOO00
L O 000
/oooo
0
0
e
Y
6
6
/O
WEEKS L y A C E l Eie47ED WcQ;rrviNG FIGURE 6. TOXICITY-PERMANENCE RELATIONSHIPS FOR A GRADE1 ERICA AN WOOD-PRESERVERS' Assocr~~rox CREOSOTE
periods of the final run show that the wood originally had 47,700 per cent excess creosote, and that at the end of the run this figure had dropped to 421 (a total decrease of 99.1 per cent in the protective power of the creosote), but yet there remained more than the minimum quantity required to
February, 1934
I N D U S T R I A L AND E N G I N E E R I N G C H E M I S T R Y
protect the wood. Since representative blocks which contained exactly the same quantities and types of creosote as those represented in Table IV had been exposed to fungi cultures with negative results, it can be said that this method of calculating the ability of residual oil to protect wood is largely substantiated. When the per cent of excess creosote is plotted against the weathering time, the result is a measure of the service efficiency of the creosote, for it coordinates the toxicity factor and the permanence factors as represented by the per cent remaining and the time. Figure 6 represent$ the data of Table IS' plotted in this manner. The curve shows that initial toxicities, by themselves, have little practical significance. Initial toxicity figures are evaluations of the poisonous properties of creosotes before they have been subjected to weathering conditions. As soon as they arc placed in service, their characteristics begin to change as the result of evaporation and water leaching. At first, as shown in Figure 6, this change is quite rapid, but the curve flattens out after the more volatile constituents have left the mood and the rate of decrease in protective value can be said to be slight after the initial period has been passed. It is possible that the flat portion of the curve represents the condition of a creosote during the greater part of its service life. The data obtained from partial weathering cycles show that evaporation brought about by heat and air is responsible for the larger portion of the changes in characteristics of creosote brought about by weatheoing. Work of previous investigators has indicated that evaporation at temperatures lower than 30" C. is slow and that oils distilling above 270" C. can be considered to be practically permanent a t such a temperature. However, slight elevations in temperature, such as those resulting from direct exposure to sunlight, cause large increases in the rate of evaporation and also raise the vapor pressures of materials distilling above 270" C. to a point where significant percentages of this material also can be lost. The action of water is subordinate to that of heat and air, causing relatively small losses of oil by actual weathering processes. A secondary action of water is reflected in the mechanical removal of whole oil. The extent of this action on creosoted wood in service cannot be stated from the results of this work, but it should be noted that the large surface-volume ratio of the test blocks has magnified the extent of this action. The actual weathering of creosote by water is confined to the more polar compounds and to the hydrocarbons distilling below 270 " C. The rates of evaporation obtained in the open-pan evaporation tests are given in Figure 5 and show the decided increase in rate that is brought about by small increases in the evaporation temperature. The curves show that these small temperature increases will bring about measurable evaporation of materials which distill above 270" C. These curves also show that any statement concerning the border line between permanent and nonpermanent oils must be qualified by giving the evaporation temperature. Examination of the distillation data of heavily weathered oils in the present work indicates that appreciable volatilization of materials which distill above 315" C. took place from test blocks which had a maximum surface temperature of 63" C. It should be noted that the curves in Figure 5 cannot be compared directly to those representing the rate of loss of oil from wood (Figure 3) because the surface-volume ratios differ widely. The open-pan evaporation tests have uncovered some interesting facts concerning the process by which creosotes evaporate. These tests have shown that evaporation of practically all of the material boiling below 270" C. must
183
take place before there can be any appreciable loss of higher boiling materials. Furthermore, evaporation of the higher boiling materials takes place in the same order as their distilling temperatures-in other words, by fractional evaporation. At first sight, these results would appear to be a t variance with the weathering of creosote impregnated in wood, for analyses of oils weathered while in wood always showed losses in both the 0-270" C. and 270-355" C. fractions while there was never a complete loss of the 0-270" C. fraction. However, it must be remembered that the weathered oil extracted from test blocks was an average oil, being made up of heavily weathered oil from the outer portions of the blocks and oil from the interior of the blocks which had not been weathered to the same extent. It is possible t o correlate these results to form a picture of the mechanism of weathering. The actual weathering of the creosote in the test blocks took place in the following manner: (1) loss of the 0" to 270" C. fraction from the oil contained on and near the surface of the wood as the result of evaporation and water leaching. (2) fractional evaporation of the material boiling above 270" from the surface oils t o an extent depending upon the evaporation temperature; (3) a slow feeding of constituents from the interior to the surface oils replacing those constituents which previously had been lost from the surface oils; and (4)volatilization and solution of this last material. I n this manner, the oil in the wood became progressively weathered.
ACKXOWLEDGMENT Acknowledgment is made to the Koppers Products Company of Pittsburgh, Pa., for laboratory facilities for conducting this work and to the Forest Products Laboratory, Madison, Wis., for cultures of F o m s annosus and Lentinus lepideuq. LITERaTURE CITED
(1) Am. Wood Preservers' Assoc., Proceedings, 28, 47 (1932). (1A) Atwood and Johnson, "Marine Piling Investigations," D. 120. Natl. Research Council, Washington, 1924.Bateman, E., Proc. Am. Wood-Preseroers' Assoc., 16, 251 (1920); 17, 506 (1921); 18, 70 (1922); 19, 136 (1923): 20, 33 (1924); 21, 22 (1925). Ihid., 24, 35 (1928). Ihid., 27, 142 (1931). Bateman, E., U. S. Dept. Agr., Tech. Bull. 346 (1933). Buchanan and Fulmer, "Physiology and Biochemistry of Bacteria," Vol. 11,p. 218, Williams & Wilkins, 1930. Curtin, L. P., Kline, B. L., and Thordarson, W., IND.ESG. CHEW..,19, 1340 (1927). Fredendoll, P. E., Proc. Am. Wood-Preservers' Assoc., 7 , 107 (1912). Kurth, E. F., and Sherrard, E. C., IND.ENG.CHEM.,23, 1156 (1931). Rhodes, F., and Gardner, F. T., Ihid., 22, 167 (1930). San Francisco Bay Marine Piling Comm., Final Rept. on Marine Borers and Their Relation to Marine Construction on the Pacific Coast, 1927; Ramage, W. D., and Burd. J. S., IND. ENQ.CHEM.,19, 1234 (1927). Schmitz, H., and Buckman, S., Ibid., 24, 772 (1932). Schmitz, H., and Others, I b i d . , Anal. Ed., 2, 361 (1930). Schrenk, H. von, and Kammerer, A. L., Proc. Am. Railwey Engrs.' Assoc., 15, 635 (1914). Teesdale, C. H., U. S. Dept. Agr., Forest Service C'irc. 188 (1911). RECEIVED August 8, 1933. Presented before the Division of Industria1 and Engineering Chemistry at the 86th Meeting of the American Chemical Society, Chicago, Ill., September 10 to 15, 1933. This paper, taken from a thesis submitted by H. E. Gillander to the University of Pittsburgh in partial fulfillment of the requirements for the degree of doctor of philosophy. is Contribution 271 from the Department of Chemistry of the University.
