CHEMISTRY T H E J O liRN-4I, O F I-VD li.STR1A L d.VD E~VIGILVEEKI~VG
490
ture within the desiccator. The lower part of the desiccator is p a r t l y ’ filled with anhydrous calcium chloride. The procedure is as follows: The finely divided rubber is weighed on a watch glass and placed in the desiccator. The air is exhausted and the electric current turned on. Usually one lamp is sufficient and will maintain a uniform temperature of about 60’ C. If necessary the temperature may be further reduced by placing two lamps in series. The electric current is left on for one hour and, if during t h a t time the vapor pressure within the desiccator becomes greater than 7 5 mm., the stopcock a t S is opened and the vapor exhausted. At the end of one hour the electric current is turned off and the desiccator allowed to cool. Air is then slowly admitted and the desiccator is again allowed t o stand for some time until the last traces of moisture have been absorbed by the chloride. The rubber is then weighed and the procedure repeated until the weight of the rubber is constant. For control purposes, one heating is usually sufficient. Very satisfactory results have been obtained with this type of desiccator in the analysis of rubber and compounding ingredients used in the manufacture of rubber goods. The removal of the air prevents oxidation and the heat produced by the coil, while not enough t o injure the rubber, is sufficient t o rapidly vaporize the water a t the prevailing pressure within the desiccator. For soft rubbers a thin sheet’ of dried asbestos may be placed on the tray D , to reduce the radiation of the heat from the coil. The following tables offer a fair comparison between the ordinary type of vacuum desiccator and the electrically heated desiccator and give some idea of the time saved. TABLEI-MOISTURE DETERMINATION ON GUAYULE Elcctric vacuuui de4ccatm Ordiunry vacuum desiccator Per ccnt Per cetit No lioiirs moisturc No.hours inoisture 40 . . . . . . . . . . . . . 2 3 . 6 I . , . . . . . . . . . . . . . . . . . . 20.2 (,‘I . . . . . . . . . . . . . . . . 88 . . . . . . . . . . . . . . . . . . . 136 . . . . . . . . . . . . . . . . . . . lhO., . . . . . . . . . . . . . . . . . . .
28.5 30.1 32.2
1x4 . . . . . . . . . . . . . . . . . . .
33.1 33.3
208 . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . 31.3 . . . . . . . . . . . . . . . 33 0 4’/a.. . . . . . . . . . . . . . . . . . 3 3 . 5 2’/2.. 31/2,.
32.x
TABLE11-CONGO KUBBEX Ordinary vacuum desiccator Electric desiccator Per cent Per cent Nu. hours moisture N o . hours moisture 24 . . . . . . . . . 4x.. . . . . . . . . 72.. . . . . . .
.........
0.84
. . . . . 1.02 . . . . . . . 1.02
2.................... 3 ....................
0.9x 0.38
As shown in Table I, one portion of a sample of crude guayule approached constant weight after z o S hours when dried in an ordinary desiccator, against 4 1 / ~hours for a portion of the same sample dried in the electric desiccator. Again, Table I1 shows that a sample of Congo required 7 2 hours for check weight against 3 hours when dried in the electric desiccator. 152 MAPLE ST. NEW
BRITAIN, CONN.
V O ~5. , NO. 6
A COMPACT, ACCURATE BURETTE FOR USE IN NITROGEN WORK OR WHENEVER MANY MEASUREMENTS OF STANDARD ARE NECESSARY B y FRAKKC. GEPHART
Received April 8. 1913
The accompanying drawing illustrates a burette devised for use, primarily, in Kjeldahl work but applicable in all lines of work where i t is necessary to make repeated measurements of standard solutions. The burette consists of three bulbs, blown without shoulders and delivering z j , I j , and I O cc., respectively. Two portions of 2 5 cc. each may be drawn without refilling, or likewise I O , 1 5 , 40 or 5 0 cc. From the top meniscus mark t o the lower measures 6 1 / 2inches, thereby placing each meniscus in easy reading distance without rising to adjust the zero. The stopcocks are provided with borings a t the end through which is driven a small piece of wood in front of which has been placed a small rubber washer, thereby rendering “lifting” impossible. This burette may be secured from Eimer & Amend, New York City. ’
RUSSELL SAGE INSTITUTE OF PATHOLOGY NEWY O R K
A COMBINATION APPARATUS STAND E. R . SQUIBB& SONS Received April 1 5 , 1913
I3y
’I’his dcvice has been in use in the research laboratory of E. R Squibb & Sons for some time and has proven very satisfactory in practice. The apparatus consists of a nickel-plated, upright rod, about 2 2 inches in height and I / ~ inch in diameter, secure(1 in a n iron cylinder base weighted with lead. Several attachments, adapted for various chemical manipulations, can be fitted t o thc rod. These proposed attachments consist of (see drawing) spring clamps which slide closely over the rod and lock automatically - by - binding o n the same. A clamp is easily shifted up or down or swung sideways by a slight pressure. The advantage over other such stands is its stability, neat appearance and compactness. The stand is simple, portable and can be used for many simultaneous operations. I t s uses are: I . For filtering (can hold four or more funnels). 2 . For holding burettes absolutely rigid, and perpendicular, permitting them to be easily moved up or down. Each stand may hold 2 or more burettes
n
June, 1913
T H E f O C R S A L OF I S D C-STRIAL .qLYD E.YGI-YEERI.VG C € I E a l I I S T R Y
which are movable around the axis of the rod. 3 . For supporting light condensers. 4. For holding separatory funnels. 5 . For supporting crucibles and small beakers.
I
After using, the apparatus can be set aside and occupies no more space than a n ordinary reag-nt bottle This is of importance where space is a factor. RROOHLYN, N. Y .
ADDRFSES
PRODUCTION AND INDUSTRIAL APPLICATION OF BYPRODUCT COKE OVEN GASES’ By J , BECKIPR AND L. B. ROBERTSON
In a paper covering the production and industrial applications of coal gases you will all appreciate that this subject can be treated only in a general way, without taking up more than the allowed time. We shall therefore attempt to briefly outline the process of distillation of coal and the treatment and application of the resulting gases. The first distillations of coal were performed in bee-hive ovens for the purpose of making coke. No gas is recovered from this coke-making process, and the only application of the gas produced is its combustion in the bee-hive oven over the coal in order to supply the heat and maintain the temperature necessary for the coking process. Then coal was distilled in retort ovens, for the recovery of illuminating gas. Coal is charged into these retorts and the liberated gas collected in a so-called hydraulic main. The gas next passes through a washing and purifying system and is collected in gas holders from which it is distributed to consumers, either for illuminating or household purposes. These retorts vary in size as well as in their position in the retort benches: horizontal, vertical and inclined retorts are in present use; the coal-coked in these retorts must be of a very high grade, in order to produce the best gas. Usually the desired candle power of the gas governs the quality of the coal to be used. The fuel necessary to perform the distillation of coal consists of a part of the coke produced by this gas-making process. The first chamber ovens were waste heat ovens, and, like beehive ovens, were built for the sole purpose of producing coke from coal. We call them chamber ovens to distinguish between this type and other types of ovens and retorts. The chamber oven is built in the form of a long, narrow chamber varying in size from 4 to 15 tons capacity. The division walls between these chambers contain flues in which the gas produced from the distillation of the coal is burned so as to maintain the temperature necessary for the coking process. The gas received from waste heat ovens passes through openings in the top of the oven chamber and from there burns downward through the flues. Air necessary for the combustion of this gas is admitted from the outside. The waste gases from these ovens have a high temperature and are often utilized under waste heat boilers for generating steam. There are also built, especially in England, the Mond Gas producers. Low-grade coal is charged into these producers and the gas received is used for heating purposes after recovering the ammonia and tar. -4 large amount of steam is introduced in order to keep the gasifying zone a t a low temperature to prevent decomposition of the ammonia formed. The amount of ammonia recovered from this process amounts to about 20 to 80 pounds in form of ammonium sulfate. The recovery of the by-products makes this process a very economical one. Competition, and the desire to produce gas and”coke most economically, brought a n oven on the market, which, we are sorry to say, is not by any means used enough in this country 1 Paper presented before the Chicago Section of the American Chemical Society, Hotel Sherman, February 14, 1913.
49r
1I
a t the present time for making gas and coke. This is the ByProduct Coke Oven. Long ago the wasteful bee-hive ovens disappeared from the plants of the coke and gas manufacturers in Germany. The by-product coke or gas oven is a chamber oven with a capacity of about 5 to I j tons of coal per oven chamber. These ovens are built in batteries varying from 2 5 to 70 ovens per battery. The division walls between the ovens serve as heating walls and contain either vertical or horizontal flues in which the combustion of the gas takes place. I n the improved by-product coke and gas ovens, the air used for the combustion of the fuel gases is preh:.ated in recuperators or regenerators placed under the oven chambers. The products of combustion of the fuel gases first pass through the recuperators or regenerators in order to heat them and are then collected in a larger flue and discharged through a chimney. In explaining the process of coal distillation we shall confine ourselves to the chamber oven The kind of coal to be used depends entirely upon the purpose for which the coal is being coked, whether for the production of gas only, coke only, or both coke and gas. I t coke p l a n s , the coke is considered the main product. At gas plants, gas is the main product, and the coke is considered as a by-product. The ideal way would certainly be, to consider both coke and gas as main products, which means making good gas and good coke from a given coal All this may be done in a chamber oven only, by coking certain coals or mixtures of certain coals. The chamber oven can produce a good illuminating gas as well as a valuable furnace coke, while retorts can produce a good gas but a n inferior coke which cannot be used for blast furnace purposes. The gas manufacturers must use a coal which gives a gas with a certain candle power. It is an undeserved handicap to the gas manufacturer to make gas on a candle power basis, since most of the gas is burned in mantles where the candle power of the gas means little or nothing. For this reason the quality of the gas should be judged on a B t u. basis. The Germans have long ago abolished the system of selling gas with a given candlepower. The requirements are certain heat units per cubic meter. Americans, considered as the most progressive people on earth, will undoubtedly do away with this antique law of judging qualities of gas by candle poner. If this requirement is done away with, gas, with a good heating value, could be made with a n inferior and cheaper kind of coal, which means that gas could be sold cheaper for public service. I n order to bring this about, Americans should continue their progress by adopting the mantle universally, which will allow a lower candle power gas to be used. I n the process of distillation, coal is charged into the chambers and the heat for coking this coal is transmitted from the heating flues to the coal charge. The gas evolved from the coal is conducted by means of ascension pipes to the collecting main and from there to the cooling, washing and purifying apparatus by means of a n exhauster which forces the gas through the pipes and apparatus into the holder. Immediately after the coal is charged into the oven, coking begins, forming a solid and thick mass on the surface of the coal. This mass on the outside of the charge consists of partly decomposed coal which is heated by radiation from the heating wall. The reversed side of this mass, that is, the side towards the center of the coal charge, is cooled by the coal which lays just behind it. The
