T H E JOI-RLV.-1L O F I.YDCSTRI'1L
F e b . 1917
d - V D EAVGIJEERI-VG C H E M I S T R Y
T A B L E I-RESLLTS O h SAMPLI 5 O r I ( h O n Y CO\lPOsITIO'i ."XILINE h r G T H O D FOR FILLERS 0 No 1 0 No 2 H I J UNO 1 L No 1 G X o 1 (Percentages) COMPOSITION OF SAMPLES 40.6 37.0 30.0 40.0 40 1 40.0 40.3 40.3 Pure Rubber (Fine). . . . . . 3.0 3.0 2.c 4.0 3.0 3.0 2.0 2.0 Sulfur.. . . . . . . . . . . . . . . . . 56.4 30.0 30.0 14.0 18.9 ... 18.9 1s.9 Zinc Oxide.. . . . . . . . . . . . . . . . 15.0 18.9 . . . 1 8 . 9 18.9 Xvhite Lead ( D u t c h ) . . . . . . ... ... 9.9 ... 9.9 9.9 Light Magnesia CarbonaLe ... ... 2.0 2.0 Hydrated- Lime ... 15.0 8 0 8.0 Litharge, . . . . . . . . . . . . . . . . . . . .. , . . . . . . . Xvhiting . . . . . . . . . . . . . . . . . ... ... ... 20.0 ... ... ... ... Lithopone. . . . . . . . . . . . . . . . . . . . . 1 5 . 0 . . . . . . . . . Vermilion . . . . . . . . . . . . . . . ... ... ... ... ,.. Carbon B l a c k . , . . . . . . . . . . ... 1h:'O ... ... ... ... Golden -1ntirnony. . . . . . . . ... ... 5.0 ... ... ... Maguesium Oxide. . . . . . . . , . . . . . 1 7 . 0 . .. . . . . . . Aluminum Flake.. . . . . . . . ... ... ... 33.0 ... ... Sublimed White L e a d . . . ... ,.. ... ... ... ... Asbestos. . . . . . . . . . . . . . . . Plumbago, . . . . . . . . . . . . . . I C u r e . . . . . . . . . . . . . . . . . . . ZO'X'40 9 0 ' X 4 0 100 x '%O0 F. 100 X ' 2 . 5 0 O F. 100 X' 2'50' F. 8 0 ' 2 30 .4KAI,STI(:BL RESVLTS(PERCENTAGES) B Y AKILIKE METHOD 5 s . 60 57.56 60.03 55.00 67.03 59.36 58.72 58.76 Fillers F o u n d . . 67.79 54.x ... 57.40 ... 58.40 I58.71 59.43 1.29 1.31 0.99 1.19 0.74 1.09 1.23 1.03 Organic Acetone E s t r a c t 2.00 4.50 0.88 1.82 0.9; 2.24 0.42 0.20 Free S u l f u r . . . . . . . . . . . . . . 39 34 39.53 39,33 36.86 39.44 29.60 39.75 39.17 Rubber.. . . . . . . . . . . . . . . . 0.44 8.21 0.00 0.32 9.32 0.47 0.1s Fillers in D i s h . . . . . . . . 6 9.5 ... 0.09 5.51 ... 0.82 0.36 , J , Caucho Rubber
SamDle T u m b e r
is yery slow t o dissolve, while this does not occur if the material is properly vulcanized. .We found t h a t in a few cases a n additional digestion with half t h e q u a n t i t y of solvent for j hours reduced t h e amount of mineral fillers about 0 .,j per cent. In specification work it is advisable t o make this second digestion after t h e ether has been expelled from the t u b e b y heating. In Table I , Samples 0 No. I a n d 0 KO. z are t h e same, except t h a t 0 S o . z was purposely overcured. Sample H was prepared using t h e same recipe as for Samples 0 Nos. I and 2 , b u t b y another manufacturer. Samples H, I and J were unintentionally undercured. Sample C is a hard valve. Sample G No. 14 contains Caucho rubber. Analysis of t h e fillers showed t h a t t h e rubber as found b y difference did not include all the sulfur of vulcanization. I t will be noted t h a t t h e s u m of t h e percentages of rubber found a n d of t h e organic acetone extract is slightly greater t h a n t h e percentage of rubber used in t h e recipe. T h e fillers during vulcanization and afterwards in the course of analysis have combined with sulfur t o form new compounds. If this combination of fillers and sulfur is a substitution of sulfur for some other acid radical, the resultant product would usually weigh less t h a n t h e s u m of t h e ingredients entering t h e reaction and t h e rubber found b y difference would be slightly greater thereby. We expect t o continue these experiments when other samples are available, and a final report will be made on the subject when we shall have all t h e d a t a a t hand. BOilRD O F E S T I M A T E A N D APPORTIONMENT CENTRALTESTING LABORATORY 125-177 n ' O R T H ST., XEW YORK CITY
THE FREE CARBON OF WOOD-TAR PITCHES By H. K. BENSONAXD L. I,. DAVIS Received November 27, 1916
In t h e examination of wood tars, it x-as found t h a t t h e so-called "free-carbon" of t h e residuums was esceptionally high as determined b y t h e methods generally employed for this purpose.' I t was accordingly 1 Office
of Public Roads, U
D e p t . 4gric.. Brcil. 314, I). 25.
141 C
GiXo. 14
24.44
37.0(a) 3.0 30.0
...
ii:il 4.44 6.67 6.67
... ...
...
.. ... ... ,
, . .
...
i4.11
60.44
0.80
5.04 1.48 33.04 3.60
...
0.30 24.79 I .4.3
. .
... ...
considered worth while t o ascertain whether the carbonaceous residue from carbon disulfide extraction really consisted of carbon or of probable hydrocarbons t h a t are insoluble in carbon disulfide. Previous work had already shown a marked variation in t h e solubility of bitumens in t h e usual petroleum solvents. wood-tar pitch being almost completely insoluble in petroleum distillates or turpentine. and only slightly soluble in benzol. T h e relative solubility of bitumens was therefore determined in carbon disulfide and acetone b y t h e usual method. T h e resulting residue insoluble jn a given solvent was in each case again extracted with t h e other solvent. T h e wood tars were obtained from the experimental wood distillation plant a t the University of Washington, from n commercial plant in Oregon and from a hard wood distillation plant i n Michigan. Commercial coal-tar pitches were t a k e n from a local Barrett plant, t h e petroleum asphalt from a city paving plant and t h e Trinidad asphalt from a laboratory sample. T h e results are given in Table I . TABLE I-RESPECTIVE SOLUBILITIES OF BITUMENS I S ACETONE AND C.4RBON DISULFIDE
IPI'SOLUBLE I K CSI
SAMPLE Douglas fir pitch . . . . D o u g l a s f i r p i t c h. . . . Douglas fir pitch.. . . Douglas fir Ditch.. . . H a d wood 'pitch., , , H a r d wood p i t c h . . . . Coal-tar pitch.. Coal-tar pitch.. Coal-tar pitch.. Coal-tar pitch.. Petroleumasphalt . . . Trinidadasphalt.. , ,
..... ..... ..... .....
Per cent 67.7 62.5 93.1 60.2 18.7 59.9 27.4 22.7 18.4 17.4 4.1 42.6
Residue insoluble in acetone 59.7c/, 30.1 35.3 22.0 3.1 18.0 27.4 22.6 18.0 17.1 4.0 42.1
INSOLUBLE IN
ACETONE XELTResidue ING ASH insoluble POINT Per in CS2 F. cent 57.853 200 2.9 31.1 185 1.0 34.4 150 0.8 21.3 130 0 I 2.7 0.1 17.4 0.';' 27.1 l., 22.3 0 6 18.5 0.1 16.9 0.0 3.9 95 0.0 41.8 150 31.2
Per cent 57.7 31.6 34.6 21.5 -2.9 17.5 57.5 37.1 35.3 33.0 27.1 69.0
CONCLUSIONS
I-The free carbon of wood-tar pitches cannot be determined b y carbon disulfide. 11-Acetone is suggested as a solvent in this determination for wood-tar pitches. 111-Coal-tar pitches may be classed with t h e native and t h e manufactured asphalts for t h e determination of free carbon. L.4BOR.4TORY O F I N D U S T R I A L CHEMISTRY cSIVERSITS O F \\'ASHINCTOS SEATTLE
