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SA1-.4LYTICAL EDITIOS
reasonable closeness those obtained by the gas-furnace method. It cannot be expected that any such empirical method of test can be made to give closely checking results in the hands of different operators, but there appears to be a possibility that the modified test as above described may be found useful as a rapid control method. The electrical method has a number of advantages: (11 its convenience, using only a small space and requiring only the small sample of ash obtained from the analytical determination; ( 2 ) its great saving of time as compared with the gas-furnace method; and (3) the greater possibility of attaining uniformity in heating rate and uniformity of atmosphere surrounding the samples. It is realized that objections to the electrical method may be raised, as, for example, the following questions : (1) Whether a truly representative sample of the total ash of the coal can be obtained in so small a test portion as is used in this test. (2) Whether there is a sufficiently close contact of the ash pellet with the heated platinum foil to get uniformity in this respect in successive tests. (3) Whether the field, about 3 ' ~inch (9 5 mm.) diameter, on the platinum foil affecting the radiation pyrometer reading is always uniform in temperature throughout its area,
The Philadelphia Electric Company, however, as a result
of careful and extensive tests conducted for this purpose. particularly b y successive check determinations by the same and b y different operators, is satisfied that, for the purpose of routine Rork in testing the quality of coal deliveries, the method is satisfactory and yields results closely approximating those that are obtained by the standard gas furnace. The work of developing this modified de Graaf procedure has but recently been completed in the laboratories of t h e Philadelphia Electric Company. It is proposed now to check u p the possibilities of the method by having comparative determinations made in other laboratories with which the Philadelphia Electric Company is associated. The ability of different laboratories to check each other on the same samples b y using this modified procedure will thus be determined. The Philadelphia Electric Company has found the modified de Graaf method, as herein described, to be a great time saver in checking the ash-fusing quality of coal deliveries, so that when an indication is obtained thus of a coal's testing belomthe normal requirement, then a check determination, by the standard A. S. T. M. method using the gas furnace, is run, and complaint to the coal shipper based thereon. The rapid method is found to save thus a great deal of time and expense as compared with the more elaborate standard gas-furnace method. Mr. Jones, of Laboratory D, tested on two samples the effect of running in a partial carbon dioxide and carbon monoxide atmosphere (by keeping on the platinum strip during the test a piece of charcoal), getting, under these conditions, somewhat lower figures than in air. Samples 2654 and 2655 gave thus, respectively, 2540" and 2445" F. (1393" and 1341' C.) as compared with 2680" and 2460" F. (1449" and 1349" C.) in air. The results on the three samples of anthracite coal indicate that the de Graaf method, even as modified by the procedure of the Philadelphia Electric Company, tends to give results 150' to 200" F. (83" to 111" C.) lower than the standard gas furnace. The question may be raised whether the results by the modified de Graaf method do not more closely parallel the clinkering results obtained in practical use of the coals. This cannot be definitely anmered without more exhaustive and closely controlled tests of the clinkering properties of
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these coals, although it' may be said that the consumer's report of the clinkering in practical use was not in line with the laboratory results obtained by the standard gas-furnace met hod, I n the opinion of two of the authors (Porter and Brewer), the procedure recommended by the manufacturers for use of the de Graaf apparatus, unless properly modified, is unsuited t o the obtaining of accurate and uniform results in the hands of different operators. The variation between the results obtained by different operators using the de Graaf procedure without modification may reach as high a figure as 500" F. (278" C.) depending very much upon the size and thickness of t'he test portion used and the personal equat'ion in choosing the end point. A11 the authors agree, however, that there are possibilities of working out a modified procedure somewhat along the lines of those used by the Philadelphia Electric Company arid the Seaboard By-Product Coke Company so that much more uniform results can be obtained and that the method, so inodified, may be found useful for rapid control work. Literature Cited (1) Eimer and .Imend, Circ. 402 (1928). ( 2 ) Fieldner, Selvig, and Parker, J . I n d . Eag. Chem., 14, 693 clR221). (3) R. I. 3003,Bureau of Mines. ( 4 ) Selvig and Fieidner, Bur. Mines, Bull. 209 (1919).
Subsequent Additions of Acid in Carius Combustions' David D. Hartley INDIANA UKIVERSITY,
BLOOMIKGTOS, IND.
sulfur determinations b17 the Carius method, IacidSor3IAKISG other combustions in a sealed tube, the amount of added is sometimes insufficient for complete decomposition. Also in some instances i t may be undesirable to add a sufficiently large amount of acid initially. The further addition of acid is by most methods a troublesome procedure, but the following one has been found quick, neat, and convenient. A glass tube of 5 t o 8 mm. bore is sealed a t one end and cut to a length of 5 to 10 cin., depending on the quantity of acid to be added. The open end is then partly closed, leaving an opening of 2 to 3 mm. diameter. This tube is placed upright in any convenient holder and the desired quantity of acid placed in it by means of a small-tipped pipet or a glass tube which has been drawn down to a capillary. The Carius tube, which has been sealed in such a way as to leave a capillary for subsequent opening and resealing, is opened and stood in a vertical position. The small tube containing the acid is inverted-the acid docs not flow out in this position-and brought down just over the open end of the capillary. The Carius tube is cooled with a damp towel and the acid flows in without leakage. The cooling is usually unnecessary owing to capillary action and absorption of the gases by the acid. Received M a y 12, 1930.
