A p r . , 1913
T H E J O C R , Y d L O F I ; V D U S T R I A L A*VD E.\TGISBERI,VG TAWLE 11-IN UNITSo P 100 K c
Official German subclass
u.S. exports to Germany (Concluded)
277
=SUBSTANTIALLY 0 1 LOYCToa (Concluded)
u.s. imports from Germany
XIX--DYES A K D DYE nIATERI.4I.s .illzarin dyes f r o m a n t h r a c e n e . , , , . , . . . . . 21,636 iZla Indigo, synthetic a n d vegetable. , . , , . , .... 34,609 322 Prussian blues, chrome and zinc greens. . . . 1.056 324b \Yhite lead . . . . . . . . . . . . . . . . . . . . . 4,848 . . 325 Blanc f i x e . . . . . . . . . . . . . . . . . . . . . 24,208 326a Zinc oxide . . . . . . . . . . . . . . . . . . . 18,850 20.979 32Sh Zinc dust . . . . . . . . . . . . . . .... 8,337 326c Lithopone., . . . . . . . . . . ... 7,328 327 Red cinnabar . . . . . . . . . 306 3?8a Logwood extract . . . . . . . . . . . . . . . . . . 2 , iiJ .. 3286 Fustic, Brazil wood a n d similar estract1 ,225 .. 329c r m b e r , sienna a n d earth colors , , . , .... 18,716 330 L a m p and similar b l a c k s . . . . . . . . . . . . . . 9.53; . . . 33 1 Bronze and metal colors.. . . . . . . . . . . , . 6,616 332b Copper pigments. . . . . . . . . . . . . . . . . . 1,226 8,530 .334 573 Printing i n k s . . . . . . . . . . . . . . . . . . . . . . . .... 336a Ready-made paints ground in oil.. , . , .... 8i9 336b -4rtists’ colors. . . . . . . - . . . . . . . . . ... 295 338 Graphite in manufactured forms. , , , , 21i ...... 340 Lead a n d colored pencils; c r a y o n s . , , . . , ... 2,210 XX-ETHERS A N D ALCOHOLS 348 Fusel oils: amyl, butyl and propyl alcohol. . . . . . . . . . . . . . . . . . . . . . .... 669 Crude wood alcohol.. . . . . . . . . . . . . . . 50,707 349a .... Acetaldehyde, paraldehyde.. . . . . . . . . . . .... 35 1 45 XXI-vOLATII,E OILS, SYNTHETIC PERFUMES, TOILET ~ZRTICLES 352 IVood tar oil: caoutchouc oil; animal oil. .... 65 353a Turpentine, pine needle oil a n d spirits turpentine. . . . . . . . . . . . . . . . . . . . . 269,945 353c Oil camphor, anise. elder, rosemary and other volatile oils; menthol a n d mentho1 pencils.. . . . . . . . . . . . . . . . . . . . 1,374 2.711 354 Terpineol, vanillin, anethol a n d similar synthetics. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,842 358 Toilet a n d tooth powders . . . . . . . . . . . . ... 298 XXII-ARTIFICIAL FERTILIZERS 359, .Xnimal fertilizers. . . . . . . . . . . . . . . . . 23,996 360 Bone-meal.. . . . . . . . . . . . . . . . . . . . . . . ... 82,838 .... 105,481 361 Thomas-meal.. . . . . . . . . . . . . . . . . 362 Superphosphates, e t c . , , . , , . , . , , . .... 42,160 X X I I I - E X P L O S I V ~ S ,. ~ X M ~ K I T I O X. w n COMBUSTIBLES 366 Loaded cartridges. , . . , . . , . . , , , , . , , 119 953 370 Fuses, etc . . . . . . . . . . . . . . . . . . . . . . . . . . .... 2,847
u. S. exports to Germany
Official German subclass XXIV-\TOOD
32Ob
I
CHEMISTRY
6506 664
cs imports from Germany
FIBER, CHEMICALPAPBR
Straw, esparto and other fibers; paper stock.. . . . . . . . . . . . . . . . . . . . . . . . . Tracing, blue-print, gelatine, fly, ozone and test p a p e r s . , . . . . . . . . . . . . . . . . . .
i,545
352,468
348
1,752
XXV-METALS i69d i69e
--, _,>a i77n -i i_i -b i/?C
844 850 855a 860 864 869a 869b 86% 869e 869f
Gold s c r a p . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Platinum, iridium, osmium, palladium, rhodium, ruthenium: cast, raw and not alloyed.. . . . . . . . . . . . . . . . . . . . . . . 2 Silver alloys, . . . . . . . . . . . . . . . . . . . . . . . 190 Silver scrap. . . . . . . . . . . . . . . . . . . . . . . . 312 Pig iron . . . . . . . . . . . . . . . . . . . .. . . . Ferro-aluminum, chrome, manganese .... nickel, etc . . . . . . . . . . . . . . . . . . . . . . 8,367 Aluminum plates a n d m e t a l . . . . . . . . . . 162,727 Pig lead and lead s c r a p . . . . . . . . . . . . . . . Zinc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... T i n and tin s c r a p . . . . . . . . . . . . . . . . . . . . 9,285 21,566 h’ickel and nickel c o i n s , , , , . . , . . , , , , , . Copper., . . . . . . . . . . . . . . . . . . . . . . . . . . . 3,946,378 Copper coins, copper scraps, e t c . . . . . . . 5,111 Copper alloys, . . . . . . . . . . . . . . . . . . . . . 2 3 , I62 Spiers glance.. . . . . . . . . . . . . . . . . . . . . . . .... Chrome, cadmium, tungsten and similar metals.. . . . . . . . . . . . . . . . . . . . . . . . . . , .
, .
> .. ... 24,400 117 , 3 1 I 10,186
.... 17,697 10,412
.... I ,97: F ,311 1,545 5.094
It should be noted t h a t in certain of t h e above items such as Class X V I I , sub-classes 2 8 0 6 and 317e, crude potash of 1 2 - ~ j per cent K20 a n d potassium chloride, respectirely, i t is stated t h a t some of t h e exports t o this country listed as under 1913,do, in fact, include some of 1 9 1 2 , b u t no information is given as t o t h e actual or relative size of such 1912 inclusion. b u t such inclusions do not disturb t h e general result or effect.
BERNHARD C. HESSE 90 \vILLIAM STREET NEW Y O R K CITY
ORIGINAL PAPERS
THE RELATION OF COMPOSITION OF ASH IN COAL TO ITS FUSING TEMPERATURE’ B y OSCARW. PALMENBERG
One of t h e most troublesome features in the combustion of coal is t h a t due t o t h e production of clinker. T h e production of clinker influences t h e rate of combustion and t h e cost of maintenance especially where automatic stokers are in use. A coal m a y clinker so readily under certain conditions t h a t i t becomes unfit for u s e irrespective of its fuel value. It is, therefore, of t h e greatest importance t o know whether a coal will clinker under t h e conditions for which i t is required. When coal is lmrned under a boiler for t h e production of steam i t is especially important t o know whether t h e ash will clinker and a t what temperature. The production of clinker, as is well known, is due t o t h e fact t h a t t h e ash of t h e coal, which is t h e liberated mineral matter, is exposed t o a temperature sufficient t o fuse i t , causing i t t o form a viscous mass which will 1 Presented before t h e N e w York Sectlon of t h e Society of Chemical Industry, T h e Chemists’ Club, New York, S o v e m b e r 71, 1913
flow and form cakes a n d thereby clog up t h e spaces between the burning particles of coal or coke. ,The mass of fused material offers resistance to t h e flow of air a n d robs t h e coal of the necessary oxygen t o support combustion. If t h e draft cannot be increased t o overcome this resistance t h e rate of combustion is diminished, other things being equal, in proportion t o t h e amount of clinker formed. To determine whether a coal will clinker, t h a t is, whether t h e coal has a n ash which will fuse a t a low temperature, has been undertaken in several ways a n d many have believed t h a t a n analysis of t h e ash, or t h e iron in t h e ash, or t h e sulfur in t h e coal will give t h e explanation. To show t h a t there is no relation between t h e clinkering quality of a coal a n d t h e sulfur or iron content, t h e writer has made this investigation. The following analyses of the ash together with the fusing temperature determinations on a wide range of coals u-ill readily show t h a t no conclusion can be obtained from a chemical analysis.
T H E J O U R N A L O F I i V D U S T R I A L A;VD E S G I N E E R I S G C H E M I S T R Y
278
T h e ash of coal is composed mainly of silica ( S O ? ) , iron oxide ( F e s 0 3 ) , aluminium oxide (Al203), calcium oxide (CaO), magnesium oxide (i'vlgo), sodium oxide ( N a n O ) , potassium oxide (KZO), carbopates (CO*), sulfates ( S O 3 ) a n d small amounts of phosphates. Since all coals, b u t particularly soft coals, consist of a mixture of pure coal substance a n d pyrites, bone, slate, fire-clay, etc., these elements will be present in a variable proportion depending upon t h e nature of t h e coal vein a n d t h e method a n d care b y which t h e coal is extracted from t h e ground. I n making a n analysis, therefore, of a coal sample representing a mixture of all these materials, a definite percentage of t h e component p a r t s of t h e ash m a y be obtained b u t this analysis does n o t tell us how much pyrites, bone, slate, fire-clay, etc., is present. I t is, therefore! apparently impossible t o judge from this analysis whether t h e ash will have a high or low fusing temperature. It is t r u e t h a t t h e pyrites will fuse a t a lon-er temperat u r e t h a n t h e slate, b u t since both m a y contain iron, t h e analysis does n o t indicate a method of arriving a t a conclusion to show t h e fusibility of t h e ash due t o t h e iron content. T h e problem offered is very similar t o t h a t when trying t o determine a formula b y which t h e heat value in a coal m a y be estimated. This has been tried b y using t h e percentage of ash a n d volatile m a t t e r or ash a n d fixed carbon, b u t since these constituents are so variable in their composition, depending upon their sources, i t is impossible t o arrive a t a reliable method. For this reason a calorimetric determination must b'e made. T h e following analyses a n d fusing temperature determinations were made on coals, most of which were mined i n Pennsylvania a n d samples were obtained either from t h e mine or place of consumption: TEMPERATURES A N D COMPOSITION OF THE A s i i BITUMINOUS AND SEMI-BITUMINOIJS COALS Fus. Kz0, temp. SO.!,
TABLEI-Fvsrxo
of ash h-0. 1. . . . . . . 2....... 3. . . . . .
' F.
Si02
Fez03
A1203
CaO
h7a?0. S in MgO COz coal
2i00
51.93 44.74 48.83 54.18 40.61 30.07 47.54 46.40 30.90 35.48 29.37
4.81 14.14 6.28 7.29 22.26 39.88 17.95 13.84 35.13 30.67 38.75
36.82 36.91 42.62 34.53 32.94 75 3 1 28.47 35.30 31.14 30.73 29.52
3.84 2.18 1.64 3.01 1.77 2.63 4.17 3.58 2.00 2.10 1.57
1.00 0.41 0.30 0.47 0.51 0.39 0.51 0.31 0.52 0.44 0.37
2615
2600 4 , , ' . . . . , 2600 5 . . . . . . 2400 6. . . 2332 i.. . .. . 2309 8 . . . . . . . 2300 9 . . . . . . . 2300 10 . . . . . . . 2246 11 . . . . . . 2180
1.60 4.85 3.90 0.52 1.91 1 71 0.96 0.57 0.31 0.28 0.44
0.51 1.46 1.01 0.90 2.06 2.41 2.11 1.80 2.13 2 17 3.57
OF
Ash in coal
5.15 7.88 9.1.5 6 41 9.70 8.96 11.04 13.51 6.25 7 90 10.60
COMPARISONS Iron
oxide
h-0.
Fus.
Fus.
temp. of ash
temp. of ash
Iron oxide
hro.
14.14 13.84
2615 2300
7. . . . . . . . . . . . . . . 8............... 9. . . . . . . . . . . . .
2309 2300 2300
17.95 13.84 35 13
6 . . . . . . . . . . . 39.88 . . . . . . . . . . . 38.T5
2,372 2180
5 . . . . . . . . . . . . . . 2400 6 . . . . 2372
22.26 39.88
2. 8.
11 .
............. ............
It m a y be noted from these tables t h a t some coals h a r e ash of l i k e i r o n content a n d variable fusing t e m perature, t h e n again others have ash of like fusing temperature a n d variable iron content. It would appear from these analyses t h a t there is no relation between t h e percentages of t h e various
T'ol. 6 ,
NO.4
constituents of t h e ash a n d t h e fusing temperature. Therefore, a chemical analysis is of no value t o arrive a t a conclusion regarding t h e clinkering quality of a coal. It m a y be noted t h a t although coals having a n ash with a very low iron content seem t o give t h e highest fusing ash, no definite fusing temperature TABLE II--FTiSIh.G
T E M P E R 4 T U R E S O F A S H I S CO.a!.S h R R . 4 S G C D .%CCORDIKG
TO T H E I R O N C O i Y T E S T
No.
Iron oxide
1.. . . . 2.. . . . 3.. . . . 4. . . . .
3.31 4.28 4.35 4.81 5 , . , , , 5.91 6.. . . 6 . 2 8 7.25 7.. . . 8. . . . . 7 . 3 4 9.. . . . 7.44 10. . . . . 7 . 6 2 11. . . . . 7 . 8 8 1 2. . . . . 7 . 9 4 13.. . . . 8 . 7 8 14.. . . . 9 . 1 9 15.. . . . 9 . 2 3 16.. , . , 5 . 6 2 17.. . . 10.13 18 . . . . 1 0 . 4 0 19. . . . . 1 0 . 6 9 20.. . . . 10.97 21.. . . . 11.19 23.. . . . 24.. . . . 25.. . 26.. , , , 27.. . . . 28 . . . . 29.. . . . 30.. . . . 3 1. . . . . 32.. , , .
11.28 11.40 12.27 12.77 13.47 13.82 13.84 14.14 14.54 15.15
S in coal
:Ish Fus. temp in coal O F
2950 7.19 2730 5 . 8 1 2850 5.15 2700 2912 , , , , 9 . 1 5 2600 6.41 2600 . . . . . 35.57 2850 . . . . . . . 2408 . . . . . . . . 2900 0.74 5.57 2600 1.52 1 5 . 6 1 2750 1.04 7 . 4 6 2642 . . . . . . . 2600 1.55 19.63 2822 0 . 8 9 ' 11.36 2950 1 . 5 9 17.64 2768 1.09 . . . . 2678 . . . . . . . . 2660 . . . . . . . . 2253 0.97 . . . . 2732 2372 1.04 8 . 5 3 2745 0.63 . . . . 2516 1.04 8 . 3 2 2830 1.01 9 . 0 2 2678 . . . . . . 2534 . . . . 2543 1.36 1 . 8 0 1 3 . 5 1 2300 1.46 7 . 8 8 2615 1.32 14.83 2210 1.07 6 . 3 8 2560
0.69 0.64 0.58 0.51 0.73 1.01 0.90
10.77
Fus. in t e m p coal F. .Ish
So.
Iron oxide
33.. . 34 . . . . 35 . . . . 36 . . . . 37 . . . . 38 . . . . 39 . . . . 40 . . . . 41 . . . . 42. , . . 43.. . 44 . . . . 45 . . . . 46.. . 47 . . . . 48 . . . . 45 . . . . 50 . . . . 51 . . . . 52 . . . . 53 . , 54 . . . .
15.21 15.38 15.53 15.89 16.00 17.95 19.19 19.54 22.38 22.55 22.5; 22.86 23.17 23.30 24.40 26.50 27.22 28.39 28.81 30.42 30 6;
56 . . . . 57 . . . . 58 . . . . 59. . . . 60 . . . . 61 , . . 62 . . . . 63. . , 64.. . .
36.12 36.17 38.12 38.62 38.75 39.51 39.88 40.93 44.39
33.27 5 5 . , . . 35.13
S,in coal 1.42 1.57 , ,, ,
1.22 1.63 2.11 1.79 2.41 4.56 2.09 2.00
....
1.16 2.40
7.23 2 13 3.13 1.96 2.32 3.14 2.17 2.86 2.13 3 04 2 60
'
T.98
..
, ,
,
..
,
9.74 9.90 11.04 7.90 11.33
....
.... 9.01 7.23 9.52 8.10 10.90 6.86 13.54 6.65 7.55 10.32 7.90 9.33 6.25 8.10 7.50
. . . . . . . . 3.26 3.9; 2.5; 2.41 7 68 3.51
10.11 10.60 8.22 8.96 9.08 9.34
2400 2156 2291 2610 2309 2309 2138 2380 2210 2516 2336 2372 2535 2156 2190 2192 2138 2084 2318 2246 2246 2520 2300 2264 2500 2300 2100 2180 2210 2372 2415 2318
fits a definite percentage a n d when t h e iron content goes beyond I O per cent t h e fusing temperature cannot be judged a t all. T h a t t h e sulfur content of t h e coal has no bearing whatsoever upon t h e fusibility of t h e ash is also apparent. T h e writer intends t o continue this investigation on coals from other sources with t h e object of determining whether there m a y not be some having ' practically no iron a n d showing a low fusing ash. Since t h e sulfur occurs in coal combined either with iron, lime or t h e hydrocarbons there naturally exist innume'rable combinations a n d for this reason t h e sulfur content cannot be used as a n index t o clinkering. Only in those cases in which t h e sulfur is in combination with t h e iron in t h e form of pyrites would i t be possible t o judge t h e clinkering property. if t h e iron content in t h e ash h a d a n y bearing upon t h e fusing temperature. T h e fusing temperature determination of t h e ash ' in coal will, in t h e future, displace t h e sulfur determination in such coals used for steaming purposes a n d vi11 readily show t h e fallacy of buying a n d selling coal on a n analysis basis where specifications are used containing sulfur tables penalizing beyond a certain guaranteed a m o u n t of sulfur. I t has been quite a common practice t o place I . j O per cent sulfur as a limit a n d penalize as much as four
*
Apr., 1914
T H E J O U R N A L O F IiVDC-STRIilL dlVD E S G I X E E R I S G C H E M I S T R Y
cents per t o n for every 0 . z j per cent above r . j o per cent. T h e injustice of this practice is very e r i d e n t as i t often happens t h a t coals with a high sulfur content are extremely high in heat value a n d d o n o t clinker readily at all. Since t h e sulfur has no appreciable effect upon t h e metallic p a r t s of t h e furnace, it need therefore not be considered in t h e selection of a coal for steaming purposes. T o - a r r i v e a t t h e value of a coal for steaming purposes it is therefore just as essential t o make t h e fusing temperature test of t h e ash as i t is t o make t h e calorimetric determination. If these determinations are made a n explanation is readily h a d as t o why two coals of apparently like proximate analyses will give entirely cliff erent evaporations when fired under like conditions.
give only t h e figures as found b y him in t h e reference. H u b b a r d a n d Reeve’ h a r e made several ultimate analyses of so-called free carbon, with t h e following results : From Carbon. . . . . . . . . . . 90.17 Hydrogen 2 59 Oxygen . . . . . . . . . 1.81 Sulfur . . . . . . . . . . . . . . . . 0 . 5 0 Nitrogen . . . . . . . . . . . . No trace upon a itative test.
B y J O H N MORRIS WEISS Received January 26, 1914
Percentage Iree carbon b y KINDS OF TAR toluol-benzol method Semet-Solvay coke o v e n . . . . . . . . . . . . . . . . . I O 76 Koppers coke o v e n . , . . . . . . . . . . . . . . . . . . . 6 79 United O t t o coke o v e n . . . . . . . . . . . . . . . 13 18 Horizontal retort gas w o r k s . . . . . . . . . . . . . 3; 4 i Horizontal r e t o r t gas w o r k s . . . . . . . . . . . . . . . 28 91 Inclined retort gas works.. . . . . . . . . . . . . . 2 4 . 3 1 T-ertical retort gas v o r k s . . . . . . . . . . . . . . . 3 95 \Vater g a s . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 02 Water g a s . ,. . . . . . . . . . . . . . . . . . . . . . . . 0.i R Oil gas t a r . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,18 Blast furnace . . . . . . . . . . . . . . 15.89 Lignite., . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. i 9 Hardffood.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.02 Pine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.03
,411 these analyses were taken on t h e dried tars, t h a t is, t h e samples of t a r were distilled until all water was removed, a n y oil distilling with t h e water being separated a n d returned t o t h e distilling vessel after t h e water was completely driven over. As s t a t e d before, this insoluble material is n o t pure carbon. One analysis b y D o n a t h and Asriel’ showed Hydrogen, . . . . . . . . . . . . . . . . . . . . . . S i t r o g e n . .. . . . . . . . . . . . . . . . . . . . . . Oxygen . . . . . . . . . . . . . . . . . . . . . . . . . Carbon . . . . . . . . . . . . . . . . . . . . . . . . .
This analysis a d d s u p to over
2.3 3,7 7.13 89.2
100,b u t t h e Lunge’s “ C o a l T a r a n d Ammonia,” 4th ed., p. 241.
Carbon . . . . . . . . . . . . . . . . 89.85 Hydrogen . . . . . . . . . . . . . . 3 . 3 0 S i t r o g e n . ,. . . . . . . . . . . . . . . . 1 . I O Oxygen. . . . . . . . . . . . . . . . . . . 3 . 1 7 ( b y difference) 1 28 Sulfur . . . . . . . . . . . . . . . . . . . . hlineral a s h . . . . . . . . . . . . . . . 1.34
,
-411 tars contain a substance in greater or lesser a m o u n t . which has been called “free carbon.’’ This has usually been considered as the material insoluble in hot benzol, a n d is not pure elemental carbon, b u t a mixture of this substance with insoluble hydrocarbons a n d other compounds of high carbon content. T h e amount of this free carbon varies quite considerably in t a r s from 7-arious sources, depending on t h e original coal a n d also! t o a large,extent, on t h e temperature of carbonization a n d t h e degree of superheating t o which t h e developing t a r r a p o r s were subjected. Under like conditions, t h e higher t h e temperature t h e greater t h e a m o u n t of free carbon found in t h e t a r produced. T h e extent t o which free carbon varies in t a r s from various sources may be shown in t h e following typical analyses of a number of t a r s :
T h e free carbon used for this analysis was obtained by t h e toluol-benzol method, which is described in detail in a later p a r t of this paper. illany methods have been proposed for t h e estimation of free carbon. Kraemer2 extracts t h e t a r with forty times its volume of xylol. Kohler3 heats I O grams of t a r with 2 j grams of glacial acetic acid a n d z j grams of toluol, pour; t h s mixture on two filters of equal weight placed inside of each other, a n d washes with hot toluol until ~?olorless. Kraemer a n d Spilker4 mix t h e t a r with t w e n t y p a r t s of xylol, filter off the insoluble material, wash with five parts of xylol, a n d d r y on t h e filter. T h e same authors give another method which consists of mixing one p a r t of t a r with three p a r t s of aniline, pouring t h e liquid mass on a porcelain plate of special shape. T h e insoluble carbon remains as a heavy mass after t h e liquid has been sucked into t h e porcelain a n d is removed with a wooden spatula, dried a n d weighed. T h e statement is made t h a t this method gives from 2-3 per cent lower results t h a n t h e xylol method described, due t o t h e greater solubility of t h e t a r bitumens in aniline. Hodurekj has found t h a t some solvents, of which benzol, acetic acid a n d ether are mentioned, have a precipitating action on bituminous substances, such as those contained in coal t a r , a n d has devised a method based on filtration of t h e original undiluted t a r t o determine t h e real free carbon. T h e method is, however, cumbrous a n d not a d a p t e d for practical work. H u b b a r d a n d Reeve,G after a comparison of various methods, proposed t h e use of cold carbon bisulfide as t h e solvent in testing t a r s for free carbon. T h e method was claimed t o be equally applicable t o both t a r a n d asphalt products. These authors also make mention of t h e progressive formation of further insoluble m a t t e r when t h e filtrates are allowed t o s t a n d , Proc. A m . SOL.Testing M a t e r i a l s , 11 (1911), 665. 1,unge’s “ C o a l T a r a n d Ammonia,” 4 t h ed., p . 426. a Z. a n g e u . Chem. (1888), 6 7 7 . 4 Muspralt’s Indus. Chem., 8 (1900). 3 . 5 Oesterr. Chenr. Z e i t . (1904), 365. 8 Pyoc. A m . SOL.Testing .Wuterials, 10 (1910). 420. 1
2
writer can
TO 94 26 3 .il 5 91 1 78 qual-
T h e y also made analyses of sulfur on various precipitates obtained b y digestion of t a r s with carbon bisulfide for various periods, t h e results seeming t o indicate a combination of t a r with t h e solvent. One analysis of average free carbon from coal t a r s made in t h e writer’s laboratory showed
5 0 E 4 S T 41sT STREET, NEW I’ORK
“FREE CARBON” Its Nature and Determination in Tar Products
279
