T H E JOURNAL OF I N D U S T R I A L A N D ENGINEERING CHEiMISTRY. more often it was greatest where a smaller proportion of the low-test or lighter oil was mixed with a larger proportion of the high-test or heavier oil.
A NEW BOMB CALORIMETER. By CRAS. J. EMERSON. Received August 27. 1908.
The whole scope of power engineering has for its basis fuel consumption. The rigorous attempts of late to develop and economize in all branches of power supply has led to a rather systematic investigation of the quality and relative merits of the several different forms of gaseous liquid and solid fuels. The exact heating value of fuels as determined by analysis or calorimeter test has passed from the stages of mere laboratory interest and has become an absolute necessity in the buying and selling of fuel in any considerable quantities. Users of large quantities of coal, lignite, peat, crude oil, light oils or what-not are determined t o buy the same strictly upon their heat value. The calorimeter test, probably the most accurate and satisfactory, is accomplished by means of the so-called bomb calorimeter. A small sample of fuel, carefully selected and reduced in bulk, by proper sampling, grinding and quartering (if a solid fuel) is placed in a strong receptacle and there burned completely, there being an excess of oxygen supplied. While the fuel is burning, the bomb is placed in a water calorimeter and the heat developed is measured in the usual way. There are several types of bomb at present in general use, differing principally in the method of supplying the oxygen. One type, that in which the oxygen is inserted as a gas under pressure, was originally inverted by Berthelot, and afterwards developed and refined for technical use by Mahler. The writer has recently devised a new bomb of the Berthelot type, which has many novel features, being designed particularly to overcome some of the difficulties previously encountered in the use of this type of instrument. The determination of the heat of combustion of a fuel by a calorimeter test, if done by any of the calorimeters now in use, has required considerable manipulative skill, and although this element is not entirely done away with, yet the above-mentioned design has greatly reduced the standard of requirement regarding experimental ability. This bomb is also designed with a view of durability and t o meet the exigencies encountered in an ordinary commercial laboratory.
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It is unlike previous bombs of the Berthelot type, as the receptacle instead of having one main portion with a cover, has its main portion divided and the two halves drawn together by a large nut. This design overcomes several difficulties of manipu-
P
1
r Fig.
I.
lation, giving easy access t o the interior, making the adjustments easier, and facilitating the cleaning. The insertion of the lining, whether it be spun metal or porcelain, is done with greater per-
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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 .
fection and accomplished more easily with this divided type of instrument. The operator can insert the fuse wire, platinum fuel pan and charge of fuel, with the lower cup in the bench holder, dispensing with any further moving of the pan, as is necessary where the pan is suspended from the cover, or is lowered into position after being filled. The calorimeter can is tapered a t the lower portion to conform t o the general shape of the bomb, thereby reducing the quantity of water used in the calorimeter. This feature is always desirable, the reduction in the quantity of water used giving a greater rise in temperature in proportion t o the heat developed. Any error in reading of the thermometer, or inaccuracies o i the same becomes a smaller percentage error of the whole. The stirring is accomplished with a paddle stirrer in a depending tube, which is lowered into the calorimeter, the stirrer being driven by a directly connected motor. The entire testing outfit is designed with utility and durability in view. The piping which delivers the oxygen from the supply tank to the bomb, instead of being of flexible pressure tubing, is blocked out as a rigid piece, and unlike flexible tubing, it is practically impervious to the development of leaks (Fig. 2). The lower
......... .............. . ,.......... , ,___
upper half of the bomb is adjusted in place and the large nut brings the same home against a lead gasket inserted in a groove on the face of the lower cup. The bomb is then connected to the piping leading to the oxygen supply by means of the nipple on the valve a t the top (as indicated in Fig. 2 ) . The oxygen is allowed to enter the bomb until the gauge shows a pressure of 20 atmospheres. The spindle valve is closed a t the top and the bomb is then ready for the calorimeter (Fig. I). Fuel bombs using oxygen gas under pressure, such as the above type, the Atwater, the Mahler, and others, might well be classed as standard instruments. The existing conditions in the calorimeter when the fuel is burning are such that practically no heat is lost. The composition of the fuel does not affect the accuracy of the workthe percentage of ash, water, sulphur, etc., not materially influencing the completeness of the cornbustion. The subsidiary heat-giving or heat-taking reactions, where impurities are encountered, prevalent in bombs of other types using chemicals t o supply the oxygen, are here eliminated. These pressure bombs will check each other with a given sample at hand, when operated properlythe only difference in the data involved is that of the constant of the instrument itself, which we term the water equivalent factor. This constant is properly determined by completely burning in the bomb a pure material whose calorific value is known. This substance should not be highly volatile and should be entirely free from chemically or physically combined water. Comparative determinations made with the bomb described above and the Mahler and Atwater instruments show the following results: Rind of coal. New river. New river.
....... ....... Pocahontas.. .... Fig. 2.
cup of the bomb is milled to fit a special holder, which does away with the possibility of jarring, which is liable when using a screw clamp, also dispensing with the manipulation of the screw. The general principles of operation of this new type of bomb calorimeter are practically the same as others using oxygen gas under pressure. The charge of fuel is placed in the pan, the fuse wire having been previously wired into position. The
r
Value as det. by Em. Fuel. Cal. 14985 B.T.U. 14900 B.T.U. 14950 B.T.U. 14915 B.T.U.
Value as det. by Mahler bomb. 14880 B.T.U. 14900 B.T.U.
Value as det. by Atwater bomb.
14910 B.T.U.
The agreement of the comparative determinations is extremely close. [CONTRIBUTION FROM
THE
FOODDIVISION
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THE
BUREAU 08
CHEMISTRY .]
THE MANUFACTURE OF OIL OF LEMON AND CITRATE OF LIME IN SICILY. B y E. M. CHACE. Received July 18. 19008.
The Island of Sicily is situated in IZJJO to 1 5 3 O longitude east of Greenwich, 369' t o 383' north
