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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 E N G I N E E R I N G C H E M I S T R Y
perature higher t h a n the temperature of liquid air, C., t h e condensate was placed in a Dewar s a y -140' flask and stirred with a test tube into which liquid C. was reached. Upon reair was run until -140' moval of the test tube containing t h e liquid air t h e condensate warmed up slowly, about 5' C. t o IO' C. per hour, thereby affording sufficient time for the withdrawal of t h e vapors. If t h e condensate rose t o a higher temperature t h a n was desired i t was a simple matter t o introduce a little more liquid air and cool it. Temperature measurements .were made with two pentane thermometers. They agreed with each other a n d gave within I . 5' C. the true melting points of chloroform and carbon disulfide, and the temperat u r e of solid carbon dioxide a n d acetone. Fresh liquid air as i t usually reached the laboratory from a plant C. near-by had a temperature of -193' The determinations of t h e traces of hydrogen sulfide, acetylene, carbon disulfide, ammonia, etc., t h a t might have been present in the gas were not attempted. Future work on t h e fractionation of artificial illuminating gas will cover the analyses of gas t h a t is used in other cities t h a n Pittsburgh and t h e separation of t h e illuminants in the coal gas before i t is mixed with carbureted water gas and in oil gas t h a t is used t o enrich water gas. CHEXICAL LABORATORY U.s. BUREAUO F MINES PITTSBURGH, P A .
SPEClFIC GRAVITY-ITS DETERMINATION FOR TARS, OILS AND PITCHES By JOHN MORRISWEISS Received September 24. 1914
T o the average chemist, the subject of specific gravity is one which, on first glance, seems t o present few, if any, difficulties. It is a p,roperty which is an absolute quantity for a n y substance a t a given temperature. Unlike many of t h e other properties of substances determined. in t h e t a r industry, it is not an arbitrary figure obtained b y a very definite method with very careful attention t o manipulative details, b u t may be determined by any method which is theoretically correct, t h a t is, when t h e mass and volume relative t o water are determined a t a n y specified temperature. Therefore, i t would seem t h a t on this test, a t least, laboratory workers should have no difficulty in obtaining consistent check determinations, both with themselves and others. As a matter of fact, i t has been the writer's experience, so far as t a r products are cpncerned, t h a t very few tests are susceptible of as grave differences in individual results as t h e specific gravity test. I n the writer's opinion, this is due partly t o t h e fact t h a t all workers do not give sufficient attention t o the importance of detail in this test, so t h a t often a method, perfectly correct theoretically, may, b y unintentional neglect, give incorrect results when carried out in practice. It is therefore necessary t o select a method based on sound theory, which can be carried out with t h e minimum amount of care b y the worker, and then
21
so standardize the details of manipulation t h a t , if directions are followed, t h e true result will be obtained with a sufficient accuracy for the purposes involved. It is the writer's intention t o review t h e specific gravity methods now in standard use in the laboratories of t h e Barrett Manufacturing Company, in the hope t h a t they may be of use t o chemists who have t o carry out specific gravity determinations on t a r and t a r products, or other similar materials. Most of t h e special methods described have been developed to a large extent in the writer's own laboratory. T h e descriptive part of this paper may be divided into t w o parts: First, oils; Second, tars and pitches. I n t h e course of the paper, attention will also be given t o temperature correction factors, their use and misuse. I-OILS
I n this connection we shall consider oils from coal t a r and other tars, presupposing sufficient quantities of material for the ordinary test. I n addition, we shall deal with methods t h a t are used when only small quantities of oil are available (less t h a n 2 0 cc.) as is the case in road compound testing, where 'the specification calls for the distillation of I O O g. and a subsequent specific gravity of the distillate oil; and also, when a Hempel distillation, according t o t h e Forest Service method for creosote oils, is carried out, and specific gravities are required on the narrow fractions taken. A . O V E R 100 CC. O F O I L AVAILABLE-POT any ordinary work, a standardized hydrometer gives sufficiently accurate results. Our custom for creosote oils is t o have a set of three, i. e., 1.000t o 1.080, 1.070 t o 1.150, and I . I j 0 t o 1.230, compared t o water a t 15.5' C. These are approximately 2 2 5 mm. long; the stems are about 1 2 5 mm. in length and t h e bulbs 24 mm. in diameter: such dimensions adapt them for use in a I O O cc. cylinder of the ordinary type. They are subdivided t o I in t h e third place of decimals. For oils lighter than water, similar hydrometers of different ranges are used. The standard temperatures a t which the specific gravities of creosote oils are taken are I 5.5 O C./I 5.5 ' C., and 38' C./15.5' C. As most oils are liquid a t 38' C., there is no reason why specific gravities should not, when t h a t temperature is required. be taken a t t h a t exact point. If, however, for a n y reason the reading is taken a t a point above t h e one desired, as is often t h e case, a correction may be made b y adding 0.0008 for every degree Centigrade t h e temperature is above the standard. T o express this in a formula: Sp. gr. 15.5'/15.5'
=
Sp. gr. X'/15.5' 0.0008 (XO-
+
15.5')
If, for any reason, a specific gravity bottle or pycnometer is used a t a temperature higher t h a n normal, this correction cannot be applied directly. It is clear t h a t with a pycnometer, the oil must be compared with water a t t h e same temperature, owing t o the fact t h a t t h e absolute capacity of any container varies with the temperature. It is necessary first t o calculate t h e specific gravity X/15.5' from t h e found figure of X / X and then apply the correction factor given
T H E J O U R N A L 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
22
above. This can be done conveniently by multiplying t h e figure a t X / X by the specific gravity of water a t X " compared t o water a t 1j.5'. T h e figure for water can be obtained or calculated from density tables given in many reference books. T h a t is: Sp. gr. r j . g o / l j . g O = Sp. gr. X/X X Sp. gr. water X/lg.j0 o.ooo8 (X-15.5") It should be borne in mind t h a t this correction factor of o.ooo8 per degree centigrade is t o be used only on coal t a r creosote oils. It is necessary because these oils are frequently solid a t 1 5 . 5 ~C., and t h e specific gravity must of necessity be taken a t a higher tempcrature. Coal t a r light oils and distillates from other tars are usually liquid, and can be taken a t 15.5' C. Therefore, no very exact correction figure for such substances has been determined. However, if great accuracy is not desired, t h e same factor can be used for these other materials, if suitable means of cooling arc not a t hand.
Vol. 7, No. I
A piece of ordinary glass tubing ai about 7 mm. outside diameter is sealed a t one end with a short platinum wire melted into the glass where sealed. This is allowed t o cool, and about g-IO g. of mercury,
+
u.
or
LESS T H A N I O 0 CC. B U T NOT M O R E THAN 2 0 CC.
AVAILABLE-such cases are comparatively rare, the occasions being when a two-ounce mailing sample is received by a iaboratory, and, therefore, there is insufficient for a hydrometer test. Here it is best t o use a Westphal balance with the regular plummet. I t is necessary i n this case t o take t h e specific gravity compared to water a t the same temperature, 'and Torrect t o the desired temperature in the same way as described under A , for the correction of pycnometer gravities. C . L E S S T I I A N 2 0 CC. Of OIL AVAILABLE-The method described can bc used whcn as little as 8 cc. of oil are available, and is rapid, convenient, and sufliciently accurate. Any laboratory possessing a Westphal balancc can readily use it. As its largest use is in taking specific gravities of small fractions obtained from a Hempel distillation of creosote oil, and as these frequently have limpid points above 50' C., we oiL
Fir. I
have fixed on 60' C. as the standard temperature a t which to make such measurements. A special plummet is used, which is small enough t o go in an ordinary I D cc. cylinder. This plummet can be made readily by any laboratory worker with elementary glasshandling knowledge.
Fir.. I1
making a column about 35-40 mm. high, is placed in the tube. It is now cut off t o within 20 mm. of t h e top of the mercury, and sealed off with a blowpipe flame. T h e plummet when complcted is about 55-60 mm. iong over-all, and should have a weight of from I O t o 1 2 g. A picture of the Westphal balance equipped with such a plummet, is shown in Fig. I. Beside the balance is shown t h e heating bath used, which consists of .a quart open-top tin can and a ring burner. I n using t h e plummet, t h e weight necessary t o balance i t in both air and water a t 60" C. is noted. Similarly, the weight required t o balance t h e plummet in oil a t 60- C. is observed. Then l f a = weight required t o balance plummet in air, b = weight required t o balance plummet in water, c = weight required t o balance plummet in oil, c- a Specific Gravity of Oil = -- ~. b-a T h a t this is theoretically correct may be shown by the following reasoning: h - a represents t h e lifting force exerted hy water on the plummet, or, a volume of water equal t o t h a t of the plummet has a weight which is represented b y h - a . Similarly, c - a represents the weight of a volume of oil equal t o the volume of water whose weight is represented by h - a. As with equal volumes, specific gravity is taken as the relative wcight of the substance t o water, ca Specific Gravity of Oil = ~- -~ as given above 6-a' Occasionally, especially in road compound speci-
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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 ENGINEERING C B E M I S T R Y
fications, the specific gravity of the oil at I j . 5 " / 1 j . S o i s required. This may be obtained approximately by multiplying the figure found a t 60"/6o" by the specific gravity of water a t 6 o o / i j. j o ,and adding 0.036 t o t h e result. Sometimes there is even too little of the fraction for this method, in which case recourse must be had t o some other device. A I cc. specific gravity bottle may be used, b u t m.e have found t h a t a I cc. pipette a n d a piece of sealed glass tubing, a s shown in Fig. IT, is very convenient for this purpose. T h e pipette is standardized by drawing water a t 60° C. u p into the pipette several times t o warm it, then adj the mark, wiping off the outside with a b paper, inserting i t in the glass tube sealed at,,one end, a n d weighing i t on the balance. The pipette is then dried and the process repeated with the oil to be tested. A piece of rubber tubing on t h e end of t h e pipette, which is removed before weighing, serves t o protect i t from the moisture of the mouth. A small piece of German silver wire, twisted about the pipette near the top, is formed into a ring t o support i t from the hook above t h e balance pan (see Fig. 11). With this arrangement, results a,ccurate only in the second place of decimals can be obtained. 11-TARS
with tar. The weight of the pan filled with t a r is taken first in air and then in water a t 15.5' C . Let a = weight of pan i n air. b = weight of pan in water. c = weight of pan plus t a r in air. d = weight of pan plus t a r in water. C - a Then Specific Gravity of Tar = ( b C) - ( a d)
+
+
After the test, the pan is held by a pair of tongs and warmed over a burner, the t a r pouredout, the pandipped in benzol or naphtha, and burned off, t h e entire cleaning operation being complete in two minutes. One standardization suffices for a considerable period: of time, and need be repeated only when a new thread is taken, or whcn high-ash materials, such as blast. furnace tar, are being handled. T h e method is quick,. clean and accurate.
A N D PITCUES
A. TARS-With tars, the method used depends on t h e consistency of the materials handled. For thin materials, like water gas tars, a specific gravity bottle which is a combination of the Regnault and t h e Hubbard types, of approximately j o cc. capacity, is usually employed, tilling the bottle with t a r and adjusting t o the mark a t t h e specified temperature of I j . 5 ' C . T h e water content of the bottle having been predetermined a t the same temperature, a simple division gives t h e specific gravity. For the more viscous coal tars, such a method is not applicable. Our standard practice on these materials is t o use the same type specific gravity bottle' and partially fill with tar, adjusting t o the mark r i t h water. This method, howevcr, has several disadvantages, i. e . , i t is slow a n d tedious, the large-mouth bottle has a tendency t o leak if the stopper is not very carefully ground, and there is considcrable breakage of the bottles. Accordingly, we developed in our laboratory what we call the "platinum pan method," and use i t almost exclusively ' for viscous t a r s and pitches. A drawing of this pan is shown in Fig. 111, and a picture 01 the same in It is made use in Fig. I V . entirely of platinum, and the supporting wires are joined t o t h e pan a n d t o each other b y heavy platinum solder. It has a total weight of about 7 E. The method of use is simple. It is suspended from the balance pan by a fine, waxed silk thread, and its weight in air and water a t I j. j oC. determined. T h e pan is then ignited over a burner, let cool, and filled %
2.3
S . R. Church, THISJ o o a m ~S,(1911). 227; 6 (1913). 195.
FIG.
1v
The use of the hydrometer on tars, though close enough for very rough work, is not t o be recommended. For coal t a r works tests, i t is sometimes used, a factor of 0.00068 j per degree centigrade being used as a temperature correction. B. P I T C H E S - H e r e the bottle method is standard for the softer pitches, with t h e alternative of suspension by a thread in air and water for pitchcs which are hard enough. For the same general reasons given under tars, we find the pan method more convenient and equally accurate. A lump of the pitch, if hard enough, is used without melting. In the harder pitches, good checks are not obtained as readily as with softer ones. This is because i n cooling the melted material, voids are formed in t h e interior, due t o contraction after the surface has hardened. For ordinary work, our practice is to take a lump of the pitch as i t comes t o hand, though in some very exact work we have s l o ~ l y
24
T H E J O U R N A L 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
cooled t h e pitch under slight pressure, t o avoid t h e formation of voids. T h e slow cooling always caused a marked increase i n apparent specific gravity with t h e harder pitches, while with soft pitches t h e difference is negligible. T h e writer hopes t h a t this paper on t h e homely subject of specific gravity will be useful i n some measure t o workers in general, a n d can s t a t e t h a t , i n his experience, t h e methods recommended here are rapid, convenient, a n d sufficiently accurate, RESEARCH DEPARTMEKT, BARRETT MANUFACTURING Co. 17 BATTERY PLACE. NET%' YORK CITY
OILS OF THE CONIFERAE: IV. THE LEAF AND TWIG OILS OF DIGGER PINE, LODGEPOLE PINE, AND RED FIR By A. W. SCHORCER Received November 2, 1914
It is well known a t t h e present time t h a t t h e oleoresins of t h e digger pine ( P i n u s s a b i n i a n a ) a n d Jeffrey pine ( P i n u s jejveyi) yield oils consisting almost entirely of n-heptane. Examination of t h e leaf a n d twig oil of t h e digger pine has revealed t h e very interesting fact t h a t heptane was present in t h e sample t o t h e extent of only about 3 per cent, t h e remainder of t h e oil consisting of aromatic bodies which are principally terpenes. It m a y be assumed with safety t h a t this small percentage of heptane was derived from t h e small twigs during distillation, since t h e latter were n o t separated from t h e leaves. T h e phytochemical processes taking place in t h e leaves a n d in t h e woody portions of t h e tree are, accordingly, entirely different, since t h e oil from t h e former consists of aromatic compounds a n d t h e oil from t h e latter of aliphatic derivatives. Anisic acid was obtained b y oxidation of certain fractions of t h e oils from digger and lodgepole pines. Lack of material prevented obtaining conclusive evidence a s t o t h e parent substance from which t h e anisic acid was derived, a n d for t h e same reason t h e presence of borneol a n d certain terpenes can n o t be shown with absolute certainty. T h e d a t a obtained, however, should be of i m p o r t a n t assistance t o t h e chemist who is fortunate enough t o obtain material for further investigation. LEAF A N D T W I G OIL OF DIGGER PINE
(Pinus s a b i n i a n a , DOUGL.) T h e physical a n d chemical constants of t h e oils are given in Table I. T h e sample of 238 grams gave t h e following fractions: I O O ~ - I ~ 6~ . 0~ ,per cent; 152'-160', 10.0 per c e n t ; 1 6 0 ~ - 1 7 0 ~5, 2 . 0 per cent; 1 7 0 ~ - 1 8 8 ~ 1, 5 . 0 per c e n t ; 1 8 8 " - 2 3 5 ~ , 8.5 per c e n t ; 235'-2goo, 2.3 per c e n t ; residue, 6 . 0 per cent. HEPTANE-The lower boiling portions of t h e oil were fractionally distilled a n d repeatedly t r e a t e d with concentrated sulfuric acid. B y this t r e a t m e n t 7.2 grams ( 3 . 0 per cent) of oil were finally obtained, having t h e specific gravity 0.7013 at I 5 ' a n d boiling between 9 8 . 5 a n d 101'. P u r e n-heptane boils at 98.4' a n d has a specific gravity a t I ~ of O 0.6880.
V O ~ 7. , NO. I
ff-PINENE-The fraction boiling a t 156-157 ' h a d 0 . 8 6 1 8 a n d ( ~ ~ 2 -26.24'. 0 0 A good yield of pinene nitrosochloride was obtained. T h e nitrosochloride was thoroughly washed with methyl alcohol a n d dissolved i n a small a m o u n t of hot chloroform. T h e crop d150
PHYSICAL AND CHEMICAL CONSTANTS OF THE LEAFAND TWIGOILS Ester No. Optical after Per cent Sp. p. Ref. :nd. rotation Acid Ester acetylayield 15 15 aD200 No. No. tion of oil Sample DIGGERPINE: 2493 0.8566 1.4670 -20.93' 2.05 11.98 37.16 0,102 2494 0.8543 1.4708 -38.36' 1.91 9.48 29.84 0.085 2496 0.8517 1.4671 -30.75' 1.47 6.77 25.86 0.078 LODGEPOLE PINE: 2495 0.8690 1.4831 -17.84' 0.90 32.30 0.234 6.02 RED FIR: 2529 0.8665 1.4861 -16.70' 0.75 0,154 9.93 36.22 TABLEI-THE
of crystals obtained on cooling, after washing with alcohol, melted a t 104-10j '. From t h e chloroform mother liquor a further a m o u n t of crystals was obtained on addition of methyl alcohol. These crystals after washing with methyl alcohol melted a t I D j '. T h e nitrolpiperidine derivative melted a t I I 7 '. T h e t o t a l a-pinene fractions amounted t o 58 t o 59 per cent. T h e relatively small a m o u n t of oil boiling between 160-1 7 0 ' was examined for @-pinene with negative results. LIMoNErz-The t o t a l limonene fractions amounted t o about 24 per cent. T h e fraction boiling a t 1701 7 5 ' a n d having 0LD21° -40.79' gave negative results for phellandrene. Sylvestrene was apparently a b s e n t since t h e dihydrochloride obtained melted a t 49-50'. T h e fraction boiling at 1 7 5 - 1 7 7 ' yielded a tetrabromide melting a t 1 0 4 ', t h e melting point of limonene tetrabromide. E S T E R FRACTION-The portion boiling at 206-23 j ' was saponified a n d distilled with steam. T h e recovered oil was t h e n oxidized with a saturated solution of potassium permanganate a n d again distilled with steam. Only a few drops of oil having t h e odor of camphor were obtained. O n acidifying t h e oxidation liquor a n acid was obtained t h a t crystallized from h o t water in t h i n needles a n d sublimed readily, giving crystals melting a t 183-184'. A portion of t h e acid weighing 0.1637 g. required 10.62 cc. of N / I O N a O H for neutralization, giving a neutralization equivalent of 1 5 4 . 2 . T h e properties of t h e acid showed i t
OCH3
t h e latter melting t o be anisic acid, CaH4
