April, 1931
INDUSTRIAL AND ENGINEERING CHEMISTRY
mercial oleic acid ( H ) . Curve G is smooth, a t all points below the mean line and is little different from other curves. Curve H is one of the most remarkable so far encountered in that it is practically a straight line. It has a slight curvature which carries it above the mean line, but for all ordinary purposes may be considered straight. Figure 4 shows the curves obtained by adding increasing amounts of double-distilled cottonseed fatty acids to doubledistilled coconut oil fatty acids ( I ) , double-distilled corn oil fatty acids ( J ) , and double-distilled garbage-grcase fatty acids ( K ) . Curve I is irregular, showing three distinctly different curvatures, but a t all points is below the mean line. At its greatest separation it is 4.1 degrees below. Curve J is a gentle, smooth curve, very slightly depressed a t 50 per cent, a t all points above the mean line, but a t its greatest separation is only 0.75 degree above. Curve K shows two different rates of curvature, both, however, convex to the mean line. Figure 5 shows the curve obtained by adding increasing amounts of double-di~t~illed cottonseed fatty acids to a high-
415
grade commercial oleic acid. It has been verified as to general form with other cottonseed fatty acids mixed with other red oils and consequently is not to be considered an anomaly. Its greatest distance above the mean line is almost 6' C. This appears all the more remarkable when it is considered that a t 25 per cent cottonseed fatty acids the titer is 0.5 degree below the mean line and rises to 5.5 degrees above after the addition of only 5 per cent more cottonseed fatty acids. Further work is planned to determine which constituent of the cottonseed fatty acids causes this unexpected result when mixed with oleic acid. Acknowledgment
Acknowledgment and thanks are due for the assistance of various co-workers in the laboratories of Armour Soap Works in determining many of the actual titers. Literature Cited (1) American Chemical Society, Fat Analysis Committee, IND. ENC% CHBM.,18, 1346 (1926).
Isolation and Identification of a Polysaccharide from Southern Yellow Pine' E. Leon Foreman and D. T. Englis CHEMICAL LABORITORY, UNIVERSITY OF ILLINOIS, URBANA, ILL
TUDIES of the composition of American woods have been made primarily with the idea of establishing the value of the different species for use in certain industries. I n the course of these analyses mgny interesting observations have been made of products of more or less secondary interest a t the present time, but which may later prove to be of significance. One of these is a water-soluble polysaccharide called e-galactan. This material was Erst isolated from the western larch by Schorger and Smith (3). On the basis of an unusually high yield of purified galactose obtained by hydrolysis of this polysaccharide, these investigators concluded that the polysaccharide contained only this one sugar as its monosaccharide component. The abnormally large ttmount of furfural formed by distillation of the compound with 12 per cent hydrochloric acid was attributed to a peculiar structure of the galactan molecule rather than to the presence of a pentosan residue. More recently, however, Wise and Peterson (4) have definitely shown that the e-galactan yields a pentose constituent which they have identified as arabinose. A series of analyses indicated 11.95 per cent of anhydroarabinose and 84-85 per cent of anhydrogalactose. Schorger and Smith have also pointed out that most of the coniferae were characterized by the presence of galactans P i n u s palustris, P i n u s seratina, P i n u s heterophvlla, and Pseudotsuga taxifolia were found to give mucic acid on oxidation by nitric acid. Pinus tueda gave anomalous resultsnegative with two samples and positive with one. Quantitative determinations were not attempted, as they had already shown that the mucic acid method gave unreliable results when sugars other than galactose were present. During an investigation of the action of high-pressure steam on southern yellow pine (Pinus palustris) now being carried out in this laboratory, it was noted that certain of
S
1
Received February 4, 1931.
the concentrated aqueous extracts yielded a polysaccharide material which later proved to contain galactose and arabinose and to resemble the polysaccharide of the western larch. Isolation of Arabinogalactan from Pinus Palustris
The treatment of the wood with high-pressure steam, the Masonite process, has been described (1, 2). The "cyclone condensate" mentioned in this investigation is the aqueous material accumulating in the cyclone separators. Some extraction of the fiber occurs here. The cyclone condensate was evaporated in vacuo to a thin sirup. The sirup was defecated with lead acetate and deleaded with disodium phosphate. The clarified sirup was slowly poured into six volumes of 95 per cent ethylalcohol with constant stirring. After the precipitated polysaccharide had settled, the supernatant alcohol was decanted carefully. The polysaccharide was washed by decantation with alcohol until the material was well dehydrated, and then washed several times with ether. The precipitate was filtered onto a Buchner funnel and dried in the vacuum oven a t 70" C. To ascertain whether the substance was formed on exploding the wood or whether it was a natural constituent of the wood, a portion of the wood was extracted. The wood was first extracted with ligroin (b. p. 65-110" C.) in a Soxhlet apparatus for 8 hours. The residue from the ligroin extraction was extracted with water for 40 hours in the apparatus described by Wise and Peterson (4). The extract was concentrated and the polysaccharide precipitated exactly as they recommend. The arabinogalactan as isolated was a white, tasteless powder, readily soluble in water but insoluble in alcohol and ether. The polysaccharide had practically no action on Fehling's solution, but was readily hydrolyzed by heating
INDUSTRIAL AND ENGINEERING CHEMISTRY
416
with 2 per cent hydrochloric acid for 2 hours a t 100" C. The hydrolyzate was strongly reducing. Hydrolysis:.of Arabinogalactan Chemical Constituents
Three grams of the dried polysaccharide were dissolved
in 150 cc. of 2 per cent sulfuric acid contained in a 250-cc. beaker. The beaker was covered with a watch glass to prevent excessive evaporation and placed in an air bath which was maintained a t 100" C. for 8 hours. The solution was cooled and nearly neutralized with a hot aqueous solution of barium hydroxide. The alkali was added slowly and with constant stirring to prevent local overheating. The neutralization was completed with barium carbonate. The neutralized hydrolyzate was evaporated in vacuo to a thin sirup. The sirup was treated with ethyl alcohol to precipitate a small amount of gum which was always present, filtered, and the alcohol removed by evaporation in vmuo. The hydrolyzate was then treated with methanol containing a small amount of acetic acid and seeded with a crystal of galactose as described by Wise and Peterson. When, after standing in the ice box for 3 days, no crystals separated, the methanol was removed by evaporation in vacuo. five grams of diphenylhydrazine dissolved in the least amount of 95 per cent ethyl alcohol were then added and the solution allowed to stand at room temperature for a week. At the end of this time the crystalline precipitate of mixed diphenylhydrazones was filtered onto a small Buchner funnel and washed several times with ether to remove unchanged
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diphenylhydrazine. The hydrazones were then fractionally crystallized from 75 per cent alcohol. After three fractionations the less soluble fraction melted at 186-3.87' C., which was unchanged on recrystallization. The melting point of 1-arabinose diphenylhydrazone prepared from Special Chemicals Company 1-arabinose melted at 185-186' c. under the same conditions. A mixture of the two melted a t 185-186' C. The more soluble fraction melted a t 157-158' C. A sample of d-galactose diphenylhydrazone melted a t 155-156" C. A mixture of the two melted at 156-157" C. Araban was determined by distillation of the arabinogalactan with 12 per cent hydrochloric acid and precipitation of the furfural as the phloroglucide. The quantity indicated was 12.2 per cent. The presence of galactose was further established by treatment of the polysaccharide with nitric acid and isolation of mucic acid. Acknowledgment
The authors wish to thank The Masonite Corporation for furnishing the cyclone condensate and wood chips used in this investigation as well as for the use of their laboratory during a part of this work. Literature Cited (1) Boehm, IND.ENG.CHEN.,32, 493 (1930). (2) Kirkpatrick, Chem. Met. Eng., 84, 342 (1927). (3) Schorger and Smith, J. IND. END. CAEN., 8, 494 (1916) (4) Wise and Peterson, I b i d . , aa, 362 (1930).
Dimensional Analysis Applied to the Thermal Conductivity of Liquids' J. F. Downie Smith2 37 GORHAM. Sr., CANBRIDQE, MASS.
Assuming that thermal conductivity of liquids is a Variables Affecting Thermal Conductivity of function of molecular weight, density, specific heat, s e a r c h one is conLiquids viscosity, gas constant, thermal expansion, and comfronted with the probpressibility, an equation has been derived by dimenlem of the determination of The first thing to do is to sional analysis connecting these variables. This equaa particular p r o p e r t y of a settle which properties affect tion is: fluid or solid. It often hapthe thermal conductivity of kK'/i z'/d pens, also, that this deterliquids. -c'/a p l /X'/a a mh/rt = 4 mination is difficult and reI n 1923, B r i d g m a n (3) By making certain modifications this equation can be quires special technic and exsuggested an equation giving k pensive equipment. I n such thermal conductivity, k , as simplified, and a graph is shown connecting a case it would be extremely a f u n c t i o n of the gas con2 L - ,-C convenient if this property stant, a, the v e l o c i t y of with ( K C ml/2 This graph shows a maximum could be c a l c u l a t e d from sound in the liquid, v , and error in thermal conductivity of 4.5 per cent. known values of other properthe mean distance of separaties which are more readily obtion of centers of the moletainable. If, however, it is known that the property wanted cules, d, assuming an arrangement cubical on the average. is a function of several other properties, it may be a long, The equation is tedious process to find the function. The application of 2av dimensional analysis usually simplifies the problem by reduc(1) k = F ine the number of semrate Quantitiesthat vary. Engineers are, in-generai, not familiar with this subject, and, of course, it is dimensionally correct, so in this article the principle is considered in some detail, The arrangement of the variables in the equation could avoiding proofs of the theorems. The particular problem have been determined by dimensional analysis without having is to derive an equation for thermal conductivity of liquids in the picture portrayed by Bridgman in his derivation provided terms of other properties. that k is a function of a, v, and d. The procedure is as follows:
REQUENTLY in re-
F
(5)
.
e).
u
1 Received 9
September 25, 1930. National Research Fellow, Harvard University Engineering School.
k
=
+l(a, v , d ) or +(k, a, v d ) = 0
