Oct., 1918
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
and 9. Here the water solutions gave in every case colorations similar t o those obtained in the absence of the phenols used as reagents, and the tint was only slightly influenced by the latter. But the alcohol-extracted pulp gave, in these cases, very characteristic reactions which clearly show t h a t the cane shoots contain not only a laccase (8E, g E ) , but also tyrosinase (8D, S F , gD, and especially g F , which is such a characteristic reaction t h a t i t cannot be mistaken). The presence of a laccase is further shown by the tests with hydroquinone, pyrogallol, guaiacol, and tincture of guaiac. The effect on pyrocatechin may be due t o both laccase and tyrosinase, as pyrocatechin seems t o be acted upon by both of these enzymes. The reaction obtained with tyrosin itself was not very characteristic, for reasons already explained above, and also on atcount of the well-known interference with this reaction by other substances, particularly amido acids, which often have either a n inhibitory effect on tyrosinase, or may entirely change the color produced. Tests for oxidases with potassium iodide-starch solution also gave positive results with both extracted and unextracted pulp. This reaction is not due t o nitrites, because boiled juices do not give it, nor is it obtained in the presence of N / 2 sulfuric acid. The activity of both laccase and tyrosinase diminishes very rapidly, as was already pointed out b y Browne and b y Raciborski. But the peroxidase reaction with tincture of guaiac and hydrogen peroxide could be obtained in juices t h a t had been kept for weeks, preserved with toluene. I n the light of Bach and Chodat’s theory of oxidases this may be due t o the fact t h a t the organic peroxide part of the oxidase is quickly used u p when acting upon the polyphenols also contained in the cane itself, but that the peroxidase part of the oxidase is much more stable. Since the amount of tyrosin found in the cane by the writer was extremely small, i t would appear t h a t the dark brown color of cane juices in the absence of iron is due largely t o the effect of the laccase upon the polyphenols of the cane, and only in small part
817
t o t h a t of the tyrosinase upon tyrosin. The reaction is therefore greatly different from that taking place in beet juices. The question as t o the nature of the polyphenols has so far not been taken up. Schneller suggested pyrocatechin from analogy with the beet and from the green iron reaction. During the past grinding season several pounds of eyes which are rich in polyphenols were cut off from sugar canes, and dropped directly into alcohol. Cane tops also were sliced and treated in the same way. But in spite of these precautions the materials, which were kept in the laboratory, after several mofiths’ standing, had darkened so much that i t was found impossible t o isolate any polyphenols from them in a pure state. So far we have been unable to find any pyrocatechin in these solutions, although the positive result of Wolff’s test’ would point t o the possibility t h a t pyrocatechin or some related substance is present in the sugar cane. We intend t o approach this problem by a different method and hope positively t o identify any polyphenols or phenolcarbonic acids. SUMMARY
The presence in young cane shoots of a laccase, of tyrosinase, and of peroxidase has been established. I t is shown t h a t the dark brown color of cane juices obtained in the absence of iron is due to the action of the laccase upon the polyphenols present in the cane, and to a:small extent, t o t h a t of the tyrosinase upon the tyrosin of the cane. The dark green color of cane juices from the factory mill is due t o the interaction of the laccase, the polyphenols of the cane, and of the ferrous salts formed by the action of the organic acids of the cane upon the iron of the mill. The ferrousfsalts are rapidly oxidized by the oxidases of ,the cane t o the ferric state, and these give the characteris tic idark-colored compounds with the polyphenols of the cane. LOUISIANA SUGAR EXPERIMENT STATION New
ORLEANS,
LOUISIANA
LABORATORY AND PLANT METHODS OF ANALYSIS USED IN THE COAL-TAR INDUSTRY. 11-DISTILLED TARS AND P I T C m S By J. M. WEiSs Received August 20, 1918
DISTILLED TAR TESTS CZ-WATER.
TEST
C3-SPECIFIC
Identical with B2. (PYCNOMETER).
Iden-
GRAVITY (PLATINUM PLAN).
Iden-
GRAVITY
tical with B j . TEST C4-SPECIFIC
tical with B6. 1
THISJO~URNAL, 10 (1918), 732.
Identical with B 7. Identical with BIO.
IN B E N Z O L .
TEST C7-CONSISTENCY
I n Paper I of this series’ the author presented t h e testing methods of The Barrett Company for crude t a r together with introductory matter t o which we would refer the reader of this paper All references t o previous tests noted in this paper refer t o the preceding paper.’ TEST
T E S T CS-INSOLUBLE TEST C~-VISCOSITY.
(SCHUTTE)
APPARATus-Schutte penetrometer (see Fig. IV) .z Stop watch. METHOD-The collar shall be filled by placing i t upon a flat tin roofing disk which has been coated with a thin film of vaseline and pouring a n excess of material into the collar. After cooling and contraction the‘excess material shall be cut off level with the upper edge of the plug by means of a heated knife blade. The collar shall be then immersed in water of the required temperature and left a t t h a t temperature for 1 5 min. The collar with roofing disk attached shall be screwed into the tube while the tube 1
a
Ann, inst. Pasteur, 31, 92. Figures are numbered consecutively in this series of articles.
~
818
T H E J O U R N A L O F 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 Vol.
SECT ION .r.u .LUG
*no*,na
OF
DETAILS. PENETROqETEh
SCUUTTE
@lo ,orIaGc
Tin D i s c
FIG.IV-ASSEMBLY OF
SCHUTTE PENETROMETER
is in position. The water bath shall just cover the shoulder of the tube. The tube shall be filled with water of the required temperature and t h e roofing disk removed by slipping it sideways. The time (measured by a stop watch) from the slipping off of t h e disk t o the sudden drop of t h e water in t h e tube, shall be noted and reported in seconds. PRECAUTIONS-Take extreme care t o keep t h e water bath within 0 . 5 " F. of t h e required temperature. See t h a t the thermometer used for taking this temperature is of tested accuracy. Note t h a t t h e thread on t h e collar is so cut t h a t it screws into t h e tube t o a n exact depth of l/4 in. Plug the small holes at t h e top of t h e tube around t h e handle with wax or pitch t o prevent leakage of water during t h e test. ACCURACY* 5 per cent. NOTES-AS the bitumen is displaced from t h e plug there is a very slight and gradual fall of water in the tube. The end-point is, however, a sharp and sudden drop and is unmistakable. If no temperature for t h e test is specified, the temperature (in even I O ' F., i. e., 40°, soo, 6 0 ° , etc.), at which the test gives results nearest t o I O O seconds, should be selected. TEST C ~ - C O N S I S T E N C Y
ble container, care being taken t o prevent loss b y volatilization or formation of air bubbles. T h e material shall then be poured into t h e collar in a thin stream until slightly more t h a n level with t h e top. The surplus shall be removed, after cooling t o room temperature, by means of a steel spatula, t h e blade of which has been slightly heated. The collar with plate attached shall then be placed in water at 5' C. and allowed t o remain a t t h a t temperature for at least 1 5 minutes. A suitable water bath shall be filled 3//4 full of water, placed over a burner and brought t o the temperature a t which i t is desired t o make t h e test. This temperature shall not be allowed t o vary during the test more t h a n 0.5' C. from the required point. The brass plate shall be removed from the collar a n d t h e latter with contents shall be screwed into the aluminum float, which shall then be immediately floated on the carefully regulated warm bath. As t h e plug of bituminous material becomes warm and fluid, i t is gradually forced upward and out of t h e collar until the entrance of water causes t h e collar t o sink. Unless otherwise specified, t h e time i n seconds (noted by a stop watch) from placing t h e float in water t o t h e t i m e the water breaks t h r o u g h the material shall be reported as the consistency of t h e material. PRECAUTIONS-NO test should be recorded if water finds its way into the float through the thread of t h e plug. This can be avoided by thoroughly coating the thread with grease or vaseline. Noms-In certain specifications it is required t o take the time from placing t h e float in water until the float sinks. This may make a difference of 5 t o I O seconds in t h e result. Tests are ordinarily made a t 50' C. At I O O O C. t h e test is not a t all sensitive for distilled tars.
FLOAT)^
APPARATUS-Float tester (see Fig. v). Brass plate, X 8 cm. Stop watch. METHOD-The brass collar shall be placed with t h e small end down on t h e brass plate which should be previously amalgamated with mercury by rubbing it first with a dilute solution of a mercury salt and then with metallic mercury. Sufficient of the material to be tested shall then be melted in a suitaj
1
Adapted from Bulletin 314, Office of Public Roads.
IO, No. I O
D ETAI LS . TesTcP-
0, . F L O A T
FIG. V-ASSEMBLY OF FLOAT TESTER
Oct., 1918
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 T E s T c ~ - D I S TILL ATI o N'
APPARATUS-see Fig. VI. Flask: The distillation flask shall be a 2 5 0 cc. Engler distilling flask, having the following dimensions :
................................ .................................. ...... ..................... e of tubulature. ....... ..... ..................... ..................... .... .....................
Diameter of bulb.. Length of neck.. Diameter of neck.. Surface of material t o low Length of tubulature. Diameter of tubulature.. Angle of tubulature..
8.0 15 .O 1.7 11.0 15.0 0.9 7sa
cm. cm. cm. cm. cm. cm.
A variation of 3 per cent from the above measurements shall be considered allowable. Thermometer: The thermometer shall conform t o the following requirements: The thermometer shall be made of thermometric glass of a quality equivalent to suitable grades of Jena or Corning. It shall be thoroughly a n n e a l e d . I t shall be filled above the mercury with inert gas which will not act chemically on or contaminate the mercury. The pressure of the gas shall be sufficient t o prevent separation of the mercury column a t all temperatures of the scale. There shall be a reservoir above the final graduation large enough so t h a t the pressure will not become excessive a t the highest temperature. The thermometer shall be finished a t t h e top with a small glass ring or button suitable for a t taching a tag. Each thermometer shall have for identification the maker's name, a serial number, and the letters "A. S. T. M. Distillation." The thermometer shall be graduated from o o t o 400' C. a t intervals of I O C. Every fifth graduation shall be longer t h a n the intermediate ones, and every tenth graduation beginning a t zero shall be numbered. The graduation marks and numbers shall be clearcut and distinct. The thermometer shall conform t o the following dimensions : Total length maximum, 385 m m Diameter of 'stem, 7 mm.; permissible variation, 0.5 mm. Diameter of bulb, minimum, 5 mm.; and shall not exceed diameter of stem. Length of bulb, 12 5 mm.; permissible variation, 2.5 mm. Distance 0' t o bottom of bulb, 30 mm.; permissible variation, 5 mm. Distance: 0' to 400'. 295 mm , permissible variation, 10 mm.
The accuracy of the thermometer when delivered t o the purchaser shall be such t h a t when tested a t full immersion the maximum error from o o t o z o o o C. shall riot exceed 0.5'; from 200' t o 300' C., it shall not exceed I O C.; from 300' t o 37 j oC., it shall not exceed I 5' C. The sensitiveness of the thermometer shall be such t h a t when cooled t o a temperature of 74' below the boiling point of water a t t h e barometric pressure a t the time of test and plunged into free flow of steam, the meniscus shall pass the point I O ' below the boiling point of water in not more t h a n 6 seconds. Condenser: The condenser tube shall have the following dimensions: Adapter. . . . . . . . . . . Length of straight tube Width of t u b e . . Width of adapter end of t u b e . .
......
-
........
....................
70mm. 185 mm. 12-15 mm. 20-25 mm.
1 See "Standard Method for Distillation of Bituminous Materials Suitable for Road Treatment," A. S. T. M. D-20-16, published in 1916, A. S. T.M. Standards, pages 540, e l seq.
819
Stands: Two iron stands shall be provided, one with a universal clamp for holding the condenser, and one with a light grip arm with a cork-lined clamp for holding the flask. Burner and Shield: A Bunsen burner shall be provided, with a tin shield 2 0 cm. long by g cm. in diameter. The shield shall have a small hole for observing the flame. Cylinders: The cylinders used in collecting the distillate shall have a capacity of 2 5 cc. and shall be graduated in 0 . I cc. METHOD-The apparatus shall be set up as shown in Fig. VI, the thermometer being placed so t h a t the top of the bulb is opposite the middle of the tubulature. All connections shall be tight.
yp#
P
, ,
jt."'".
c+
.
DETAIL
OF D l S T l L L A T l O t i FLASU
L
FIG.VI-ASSEUBLY
FOR
DISTILLATION TESTOF DISTILLEDTARS D-20-16
A. S. T. M.
If the presence of water is suspected or known, the material shall be dehydrated before the test is made (see B3). One hundred cubic centimeters (see note) of the dehydrated material t o be tested shall be placed in a tare.d flask and weighed. After adjusting the thermometer, shield, condenser, etc., the distillation is commenced, the rate being so regulated t h a t I cc. passes over every minute. The receiver is changed as the mercury column just passes the fractionating point. The following fractions should be reported: S t a r t of distillation t o 110' to 170" 170° to 235O 235Oto 270' 270't.o 300' Resid ue
110' C. C.
C.
C.
C.
To determine the amount of residue, the flask is weighed again when distillation is complete. During the distillation t h e condenser tube shall be warmed when necessary t o prevent the deposition of any sublimate. The percentages of fractions shall be reported both by weight and by volume. NOTE-It is usually impractical t o accurately measure I O O cc. of the materials used for distillation. Therefore, the weight corresponding t o I O O cc. should
T H E J O U R N A L O F 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 Vol.
820
be calculated from the predetermined specific gravity and this amount weighed into the flask. For example, if the specific gravity is I . 189,the operator should weigh out 118.9g. for t h e test. PITCH TESTS TEST DP-SPECIFIC
GRAVITY
(PLATINUM PAN)
This is identical with B6 with t h e special note t h a t care must be taken t o prevent the formation of air bubbles on the pitch when immersed in water. T E S T D3-SPECIFIC G R A V I T Y (PYCNOMETER) This is identical with B j with the same modifying note as given under D2.
D4-SPECIFIC G R A V I T Y ( S U S P E N D E D C U B E ) APPARAT us-Chemical balance. Wooden bridge : Usually supplied with balances. This consists of a small wooden beaker support which holds a beaker over the balance pan and a t the same time allows the pan to oscillate freely without contact with the bridge a t any point. METHOD-A lump of pitch shall be suspended from the hook above t h e left-hand pan of the balance by means of a fine waxed silk thread in such a manner t h a t the cube is about one inch above t h e pan and its weight noted. The bridge shall be applied with a beaker of freshly-boiled distilled water 3t a temperature of about 13' C. (55' F.). The lump of pitch (still suspended from the, hook) shall be immersed in the water, the temperature allowed t o rise t o 1 5 . 5' C. (60' F.), and the weight in water noted. The weight of the pitch in air divided by its loss of weight in water gives t h e specific gravity. PRECAcTIoNS--'I'Vhen weights are taken see t h a t the balance pan swings freely and does not touch the bridge or beaker. See t h a t the pitch cube is free from air bubbles.
IO,
n
C U B E of PITCH-
Wlr
TIN
SHlLLD
D U N S E N BVICNE BRAS
TEST D
TEST D6-WATER MELTING POINT APPARATUS-see Fig. V I I . Pitch mould. Hook made of No. 1 2 B. and S. gauge copper wire (diam. 0 . 0 8 0 8 in.). Beaker, 600 cc., Griffin's low form. Thermometer: The thermometer shall conform t o the following specifications: Total length.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370 t o 400 m m . Diameter.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bulb length.. . . . . . . . . . . . . .
6 . 5 to 7 . 5 mm.
4 . 5 t o 5 . 5 mm.
IO
The scale shall start not less than 7 j mm. above the bottom of the bulb and extend over a distance of 240 t o 2 7 0 mm. The graduations shall be from o o t o Soo C. in i / 5 0 C. and shall be clear c u t and distinct. The thermometer shall be correct t o 0 . 2 5 ~C. as determined by comparison at full immersion with a similar thermometer calibrated a t full immersion by t h e Bureau of Standards. The thermometer shall be furnished with a n expansion chamber at t h e top and have a ring for attaching tags. It shall be made of a suitable quality of glass and so annealed as not t o change its readings under conditions of use.
TEST
INSOLUBLE IX B E N Z O L ( F R E E C A R B O N ) All matter as to apparatus, method, precautions, and accuracy given under B7 (except as' noted below) apply t o this test on this material. S P E C I A L NOTE-If the pitch is hard enough, grinding the material taken for test will be advantageous in aiding the subsequent solution. It is well t o examine the carbon residue for foreign matter, such as wood slivers, pieces of bagging, etc. If such foreign matter is present, t h e test should be rejected. The requirement (as given under B7) t o pass t h e material hot through a go-mesh sieve does not apply to these materials.
No.
PINS
SECTION THKV
FIG. VII-ASSEMBLY
METHOD-(a)
OF
BK.LSS MOULD
TESTFOR WATERMELTINGPOINT
Pitches having melting points between C . ( I I O " to 1 7 0 ' F . ) . Acleanshaped half-inch cube of pitch shall be formed in the mould and placed on the hook of wire (see Fig. VI1 for detail of method of placing t h e cube on the wire). The apparatus shall be assembled as shown in Fig. VII, placing 400 cc. of freshly-boiled distilled water a t 1 5 . 5 ' C. in the beaker. The thermometer shall be placed so t h a t the bottom of t h e bulb is level with t h e bottom of t h e cube of pitch and shall be immediately contiguous to, b u t not touching, the cube. The pitch cube shall be suspended so t h a t its bottom is one inch above t h e bottom of the beaker and allowed t o remain in t h e water a t 15.5' C. foG'5 min. before starting t h e test. Heat shall then'be applied in such a manner t h a t the temperature of t h e 43" C. artd 77'
Oct., 1918
water is raised 5' C. (9' F.) each minute. The temperature recorded by t h e thermometer a t the instant t h e pitch touches t h e bottom of t h e beaker shall be reported as t h e melting point. ( b ) Pifiches having melting points below 43' C. (110' F.). These shall be tested exactly as under a , except t h a t t h e water at t h e start shall be 4' C. (40' F.) and t h e cube shall be allowed t o remain 5 min. a t this temperature before starting t o apply the heat. PRECAUTIONS-The use of boiled distilled water is essential, as otherwise air bubbles may form on the cube and retard its sinking. The rate of rise must be uniform and not averaged over the period of the test. All tests where t h e rise is not uniform shall be rejected. A variation of not more t h a n fo. 5' C. for any minute period after the first three is t h e maximum allowable. ACCURACY-
82 I
T H E JOURNAL. OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY
The thermometer shall be furnished with a n expansion chamber a t the t o p and have a ring for attaching tags. It shall be made of a suitable quality of glass and so annealed as not t o change its readings under conditions of use. It is desirable not t o have a supplementary bulb above t h e main bulb, b u t if this is done, such supplementary bulb must not be separated from the main bulb by a distance of more than 2 mm. 6 Vh'' 4 V4"
-
I
* 1 ' F.
E LP VAT ION DETAIL
NOTES-Pitches of t h e a range of consistency can ordina.rily be molded a t room temperature, but, if necessary, cold or hot water can be used t o harden or soften them. Pitches of the b range can be conveniently formed in water of about 4' C. (40' F.). A sheet of paper placed on t h e bottom of the 600 CC. beaker and conveniently weighted will prevent t h e pitch from sticking t o t h e beaker when it drops off, thereby saving considerable time and trouble in cleaning. This method shall not be used on pitches above 77' C. (170' F.),water melting point. Such pitches shall be tested as under ~ 7 . T E S T Dy-AIR
PLAN
o f
COPPEL C U P
MELTING POINT
APPARATUS-Melting point oven (see Fig. VIII). Tripod: The oven shall be mounted on a suitable tripod. of such size t h a t it supports the outer edge only of the oven, leaving the bottom exposed directly t o t h e heat of the burner. Burner: A Tyrell burner of type A. H. T. 22884, E. & A. 1462 shall be used for heating. I t shall be provided with a suitable chimney (A. H. T. 22984, E. & A. 1590): Hooks: %lade of N o . 1 2 B. and S. gauge copper wire (diam. 0.0808 in.). Copper Cup: This shall be of about 5 0 cc. capacity, in size I ~ / Z in. deep. b y I'/Z in. diameter. It shall be provided with a wooden handle (see Fig. VIIII. Thermometer: This shall conform to the following specifications : Total length.. .............................. Diameter of stem.. ........................... Bulb length ................................. Bulb diameter.. ............................
380 t o 385 mm. . 6 . 5 t o 7 . 5 mm. N o t over 14 mm. 4 . 5 t o 5 . 5 mm.
The graduations of the scale shall be from 30' to 160' C. in I / z ' C. and shall be clear cut and distinct. The 30' m.ark shall be a t least 7 5 mm. above the bottom of the bulb. The length between the 30' mark and t h e 160' mark shall be between 2 3 0 mm. and 2 7 j mm. The thermometer shall be correct t o 0 . 2 j ' C. as determined by comparison at full immersion with a similar thermometer calibrated a t full immetsion by the Bureau of Standards.
FIG. VIII-ASSEMBLY
OF AIR MELTING-POINT TEST(FOR PITCHES)
METHOD-The copper cup (see Fig. VIII) shall be half filled with pitch and carefully heated until melted. The cube shall then be formed by pouring into t h e mould and allowing t o cool. The cube shall be suspended in the oven on a hook of proper length so t h a t its center rests on a level with an imaginary line running through t h e centers of the observation windows. The bottom of the thermometer bulb shall be level with the bottom of t h e cube of pitch. The temperature of the oven is raised exactly j" C. (90 F.) each minute and t h e temperature recorded by the thermometer a t t h e instant the pitch drops t o the bottom of t h e oven shall be taken as t h e melting point. ~REcAuTIoNS-care shall be taken t o avoid noticeable evolution of vapors in t h e heating and melting of t h e pitch. If necessary a n oil bath may be used. The apparatus should be set up in a place free from drafts and if necessary protected by means of a shield set apart from the apparatus. The oven itself must not be lagged. The rate of rise must be uniform and not averaged over t h e period of the test. Any tests where t h e rise is not uniform shall be rejected. A variation (after the first 3 min. of the test) of * I' C. is the maximum allowable. Not over two cubes shall be run in the oven a t the same time,
T H E J O U R N A L O F 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 Vol.
822
and these shall not be pitches with melting points more than j' C. (9' F.) apart. The cubes shall be close t o but not touching t h e thermometer and equidistant from it.
4-
I-PLAN
IT-E L E V A T I o N m - s E c T ~ONTnqOUGn CENTER
U
u
I
GALVANlZEb PAINTED
LINE
IrON
bLACK.
" FIG. IX-DETAIL
OF
S H I ~ L FOR D AIR MELTING-POINT TEST
NOTES-This method shall be used only on pitches melting above 77' C. (170' F.). To make results by this method comparable with result obtained in water, 6 . 5' C. (12 F.) may be added t o the observed melting point, but the results of melting-point tests must always be reported in terms of the method by which the test is made. I n a laboratory free from drafts a shield is not necessary. If one is needed, a convenient type which can be easily constructed is shown in Fig. IX.
IO,
No.
the bottom of the bulb. The thermometer before use shall be checked at full immersion against a thermometer calibrated a t full immersion by the Bureau of Standards, and the readings used thereby corrected. Burner: The oven shall be heated by a Tyrell burner (A.H. T. 22884, E. & A. 1462),provided with a chimney of the type A. H. T. 22984, E. & A. 1590. Assembly of apparatus: Shown in Fig. X. Each dish shall be placed on a round l/d-in. asbestos pad of approximately the same diameter as the dish. The bulb of the thermometer shall rest in a pan of suitable high-flash oil, on a similar asbestos pad. The pan in which t h e thermometer bulb is inserted shall be higher than the others and need not be made of nickel. The height shall be such t h a t t h e thermometer bulb is completely immersed in t h e oil. Not more t h a n 4 pans, including the one with t h e thermometer, shall be run in the oven a t one time. The pans shall be arranged symmetrically with respect t o t h e center of the shelf of the oven. METHOD--Approximate~y I O g. of pitch shall be weighed into a dish, placed in the oven, held at 163' C. ( 3 2 5 ' F.) * z o C. for 7 hrs., removed, allowed t o cool in a desiccator, and the loss of weight noted. PRECAUTIoNs-The oven should be set up in a place free from drafts and should be regulated t o temperature before t h e dishes are inserted. NOTE-where the laboratory has a reasonably uniform gas pressure, it is advisable t o have a burner of the A. H. T. 22860 type permanently connected by iron pipe under t h e oven and provided with a shutoff cock. The regulation of the burner can then be left in t h e same adjustment between tests, thereby obviating all but minor adjustments during the test. T E S T D I I-SLIDE
APPARATUS-water-jacketed
oven (of type A.
m
TEST D I O - E V A P O R A T I O N
APPARATus-Copper drying oven, 8 in. X 8 in. X in., A. H. T. 41500, E. & A. 3030. The oven shall be completely covered inside and out with in. asbestos board, excepting the outer bottom surface. The dqor of the oven shall also be covered inside and out with the same thickness of asbestos. The shelf of the oven shall be 2 . j in. above the bottom of the oven. Evaporating dishes: These shall be made of pure nickel. They shall be 2 in. inside diameter a t the bottom and "16 in. high, tapering a t the top to a diameter of z1/8 in. (see Fig. X). They shall be provided with a suitable handle of the same material. ' to Thermometer: This shall be graduated from 0 300' C. in I O C. and of such a length that when p1,aced in position the T O O O C. mark will be within I O O C. above the cork. This requires a total length of 300 t o 350 mm. with the 100' mark about 140 cm. from
IO
IO
FIG. X-ASSEMBLY
OB
DRYING A N D EVAPORATING OVEN
H.T .
Oct., 1918
T H E J O U R N A L OF ILVDL-STRIAL A N D ENGINEERING C H E M I S T R Y
41508, E. & A. 4876), size I O in. X 1 2 in. Slide plate (see Fig. XI). Pitch mould (see Fig. IV).
SLIDE CUBE
OF
t COPPER
One of the important requirements of the method
is t h a t the distillation be conducted a t a fixed and uniform rate. To fulfil this requirement i t is necessary t o employ a source of heat t h a t can be accuratdly regulated and t h a t is not subject t o uncontrollable fluctuation. The procedure commonly employed in petroleum-testing laboratories involves the use of a gas burner equipped with gas and air regulating devices and protected from air curren% by a n enclosing screen or shield. In the laboratories of the Bureau there has been employed instead a special electric heater which has proven so advantageous t h a t a der scription is now being offer2d for general information.
eox
PITCH
823
COVERING
DISADVANTAGES O F G A S AND ALCOHOL BURNERS
\\
FIG. XI-ASSEMBLY
OF SLIDE
FRONT
TEST*'OR
ELEVATION
PITCHES
METHOD-A half-inch cube of pitch such as used for the melting-point test shall be placed a t the t o p of one of' the depressions in the corrugated plate, warmed slightiy, and pressed down so as t o present a rounded top, care being taken t o keep the lower edge intact. A mark shall be made on the adjoining ridge parallel t o the lower edge of the cube, which shall then be placed in the oven and held a t 40' C. for 7 hrs. The temperature shall be measured by a thermometer whose bulb is I in. above the center o f , the upper surface of the slide plate, and whose scale is such t h a t the effective range may be observed outside of the oven. After the 7-hr. period has elapsed, the plate shall be removed from the oven and a second mark made from the ridge parallel t o the furthest point the pitch has reached. The linear distance between the two marks shall be reported as the slide. NoTE-Very soft pitches which may run beyond the end of the slide must be observed from time t o time and the time interval a t which they reach the end of the slide noted. THEBARRGTT COMPANY 17 BATTERYPLACE,NEW YORKCITY
A CONVENIENT ELECTRIC HEATER FOR USE IN THE ANALYTICAL DISTILLATION OF GASOLINE1 By l3- W. DEAN Received May 14, 1918
INTRODUCTION
A recent techhical paperZ of the Bureau of Mines recommends and describes a method for the analytical distillation of gasoline. The discussion published deals only with such details as are essential t o the accuracy and uniformity of the method and for the sake of simplicity omits matters which concdrn only ease and convenience in manipulation. Piiblished by permission of t h e Director of the U. S. Bureau of Mines. 2 E. W. Dean, "Motor Gasoline, Properties, Laboratory Methods of Testing, and Practical Specifications," Bureau of Mines, Technzcal Paper KO.166 (1917), 27 pp. See also Am SOC.Test Mat, Year Book 1915, pp. 568-569; Part I, Committee Reports, 16 (1916), 518-521. 1
Testing laboratories generally use a source of heat for gasoline distillation, either gas or alcohol burners. The former are generally preferred, although there is now on the market a t least one type of special large alcohol lamp' t h a t the Bureau knows t o bz satisfactory. The chief disadvantage og all flame heaters is the difficulty in keeping them under proper control. Both accurate regulation and freedom from fluctuation are difficult t o attain. Moreover, ordinary gas burners are not designed for the particular requirements of gasoline distillation and d though more satisa factory types2 are undoubtedly used by many laboratories they are a t best less satisfactory than elactric heaters? I n addition t o difficulties in regulating and shielding, there are considerable losses of heat t o the surrounding air and to FIG.I parts O f the apparatus Special gas burner designed and employed for gasoline distillation b y t h e t h a t should not be Atlantic Refining Company. Burner is heatzd externally. hi^ composed of a special bronze casting equipped with sensitive needle valve and escape of heat may a screw adjustment for the regulation of the air-eas mixture. The various features prove a Source of dis- a p p e a r a s follows: a = g a s inlet; b=gas regulating valve; c = air inlet: d = screw comfort to the operator adjustment controlling air supply; e = gauze cap t o prevent flame "striking and is liable to intI-0- back"; f = mica chimney for protection of duce minor possibilities flame against drafts. of variation in the results of a n analysis. Finally the use of flame heaters for the distillation of volatile inflammable liquids introduces a n element of danger Made by the C. J. Tagliabue Manufacturing Co., Brooklyn, N. Y. The most satisfactory gas burner with which the Bureau is familiar is a type in the Philadelphia laboratory of the Atlantic Refining Company, Through the kindness of Chief Chemist I?. C. Robinson, of this company, drawings and specifications for this burner in its present state of development have been obtained and are shown in pig, I of this paper 1
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