. Journal. 100 — For De the p coal tar it 120° 17-0 20-023-526-529-532-7 3o-738-741-544-046-7 49-552-154-957-259-6 62-084-567-069-471-6 77-579-280-9 125° 130° 137° 36-3 38-841-243-445-748-0 50-252-354-556-658-6 24-727-530-333-035-7 38-240-743-145-447-6 49-851-853-555-357-2 59-060-762-363-865-3 Determnation in CkJAL Tar. For the purpose of determining the toluene in* is necessary to separate the crude naphtha from the tar by fractional distillation,and to wash this naphtha (which contains thewliole of the tohiene) with sulphuric acid be/oreapplying the test described aliove. Sufficient of the t
. Journal. 100 — For De the p coal tar it 120° 17-0 20-023-526-529-532-7 3o-738-741-544-046-7 49-552-154-957-259-6 62-084-567-069-471-6 77-579-280-9 125° 130° 137° 36-3 38-841-243-445-748-0 50-252-354-556-658-6 24-727-530-333-035-7 38-240-743-145-447-6 49-851-853-555-357-2 59-060-762-363-865-3 Determnation in CkJAL Tar. For the purpose of determining the toluene in* is necessary to separate the crude naphtha from the tar by fractional distillation,and to wash this naphtha (which contains thewliole of the tohiene) with sulphuric acid be/oreapplying the test described aliove. Sufficient of the tar is distilled to yield at of crude uai)htha. Generally, 8000 tar will be found ample. Some tars, how-ever, contain so much nai)htha that 4000 , oreven less, may be used. Part I. Distillation of the tar. The tar is placed in a glass retort or an iron still, preferably the latter. A convenient and easily-constructed still is shown in the diagram. Tar still for laboratory T. Thermometer. V. Cork loosely inserted to act as safetyvalve. C. Water-cooled condenser. GG. Gas supplies. HR. Ringburner for i>reliminary heating. DR. Ring burner employedas additional source of heat when the water has been distilled off. A thermometer is fitted in such a position that thebulb is surrounded by the vapour in the delivery-pipe of the still is connected to awater-cooled condenser. Distillation is thenstarted. The distillate is collected in a receiverwhich, when the thermometer indicates 220° C., isremoved and a second receiver substituted for this change of receivers is made, the supplyof water to the condenser is shut off. The distillateis collected in the second receiver until the ther-mometer indicates 260° C, at which point thedistillation is stopped. During the time that the distUlate is beingcollected in the first receiver, a sample, amountingto two or three drops of the distillate, should betaken periodically, and allowed to fal
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectchemist, bookyear1882
