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component of the ash. same dust were made: LOCATION:
............
Per cent G O - .
The following analyses of t h e Flue Chamber 7.79
Base of Chimney 6.40
This shows the dust t o have a higher potash content t h a n t h e ash (cedar) itself, due to t h e fact t h a t the potash is lighter and more volatile than the silica, ferric oxide, etc., which largely compose the residue left in t h e ash pits. Interviews with the foremen or managers of t h e McDonnell ’ a n d Phoenix mills a t Ballard indicated t h a t for mills of t h a t size (60,000 t o 70,000 log feet per day) the amount of ash remaining in the incinerator was under ‘/z ton per week. The general superintendent of the Seattle Cedar Lumber Company of Ballard (190,000log feet per day) stated t h a t a large new incinerator had been in service for over a year a n d had not been cleaned out y&. From these statements it may be seen t h a t a n amount of ash sufficient for large potash production cannot be secured. As has been shown, the eastern wood ashes which are used in the manufacture of potash, average over I O per cent potassium oxide. From the above analyses of incinerator ash it has been shown t h a t the average potassium oxide content is around 1 . 2 per cent. This means t h a t a company attempting the manufacture of potash from incinerator ashes would be obliged to handle nearly ten times the amount of ash, t o produce the same amount of potash. Its cost of production would be increased in nearly the same ratio. The war has increased the price of potash t o about ten times its former value. Hence under present conditions it is possible t h a t incinerator ashes might be used as a source of potash, for the increased cost of production would be counterbalanced by the increased value of product. However, if the end of the war should, as we quite reasonably expect, result in a rapid decrease in the price of potash, the production of potash from incinerator ash would not be a paying proposition. Further, in any case, the quantity of incinerator ash is not sufficient for commercial production. CONCLUSIONS
I-Potash production from incinerator ash cannot be put on a paying commercial basis (barring war prices, which are of course inflated) because of I-LOW potash content; 2-Higher cost of production; 3-Insufficient supply of raw material. 11-Unless a new method. for the disposal of waste is suggested, the prevailing method of disposal of incinerator ash is as economical as can be found. Analyses show i t t o be of little value for fertilizer. 111-If any plan were t o be suggested for the successful production of potash from wood ashes, it must fulfil the following conditions: I-Dispose of the waste as fast as i t is produced. 2-Operate a t low temperatures and with slight draughts. 3-Successfully meet foreign and domestic competition. CHEMICAL LABORATORY UNIVERSITY OF WASHINGTON, SEATTLE
Vol. 9, No. 5
AROMATIC HYDROCARBONS FROM THE THERMAL DECOMPOSITION OF NATURAL. GAS CONDENSATE BY 3. E. ZANETTI AND G. EGLOFF Received March 23. 1917
I n previous papers one of us1 has shown t h a t by the thermal decomposition of natural gas condensate aromatic hydrocarbons were produced together with hydrogen, methane and “unsaturated,” which consisted chiefly of ethylene, when t h e condensate in t h e gaseous form was heated t o a temperature above 750’. The amount of aromatic hydrocarbons obtained as “tar” was too small to permit any extended investigation and only three were positively identified, v i z . , benzene, toluene and naphthalene. By using the same method and apparatus, we were able to prepare about 2 5 0 cc. of “tar” from the fraction of natural gas condensate consisting chiefly of propane a n d butane. Even with this much larger amount, the composition of which is given in Table I , the fractionations did not allow us a sufficient amount of material t o enter into a detailed investigation and TABLEI-DISTILLATIONANALYSISOF RECOVERED OIL Specific Gravity 1.101 at 15.5’ C. Per cent Temperature Volume T o 170° C 14.1 170 to 230° C . . 13.6 230 to 270° C . . 12.7 270 to 365O C . . 16.3 Pitch 43.3 To 95” C. (Benzene Fraclion) 4.8 95 to 120° C. (Toluene Fraction). 2.0 120 to 150° C. (Xylene Fraction).. 3.9 150 to 170° C. (Trimefhyl Benzene Froclion). 0.7
................................... .............................. .............................. .............................. ................................... .................. .............. ............. ....
Sp. Gr. 0.885
... ... ... ...
0.885
0.870 0.871 0.876
isolation of the numerous hydrocarbons, which could be present, and although we had no difficulty in isolating anthracene, a much higher molecular weight hydrocarbon than we had hitherto obtained, there still remained a great number of possible ones whose presence we were unable t o show definitely, owing to the scarcity of the material. The yields of “tar” were essentially the same as obtained in the previous investigation, from 8.5 t o I O cc. per cu. ft. of the original gas, the procedure being in all respects identical, except as t o t h e rate, which was slightly greater, v i z . , about 0.6 cu. f t . per hr. At the same time we prepared, by absorbing the unsaturated gaseous products in bromine water after the “tar” had been deposited, about I kg. of the bromides TABLE11-COMPOUNDS ISOLATED: WITH PHYSICAL AND CHEMICAL PROPERTIESFOR IDENTIFICATION HYDROCARBON Boiling Point Sp. Gr. IDENTIFICATION AS Nitrobenzene 79 t o 82OC. 0 . 8 8 5 Benzene. Trinitrotoluene, M. P. 108 to 1120 c. 0.870 Toluene. 820 c. 135 to 145O C. 0 . 8 7 1 Xylenes.. Naphthalene, M. P. 216 to 221’ C. Naphthalene. 79.30 c. Slight yellow crystals, M. P. ? 1 l 0 C. Anthracene Anthraquinone. M. P. 2770.
........... ........... .......... ....... .........
which were fractionated and analyzed as shown in Table 111. The object here was t o show more definitely t h a n , before t h a t the unsaturated consisted chiefly of ethylene, a small amount of propylene and a considerable proportion of butane, as shown by the high percentage of tetrabrom butane, which was ob1 Zanetti. (1916), 7 7 7 .
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(1916), 674; Zanetti and Leslie, Ibid., 8
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OF I N D U S T R I A L .1 N U E i V G I X E E R I N G L H I S M I S I R I .
tained quite pure, showed a constant melting point and gave the required percentage of bromine on analysis. In the "residue" there vere doubtless bromides of higher hydrocarbons and possibly higher bromides of
47s
bromide 2.97 (17.j")] whereas this fraction showed only a specific gravity of 2.100 corresponding t o a mixture of ethylene and propylene bromides. Further, i t would have been practically impossible t o separate it from propylene bromide, their boiling points being TABLB III-DISTZLLITION AND A ~ n i v s i sOF BHOM DBRWIT~VES oe UNSATURITBD HYDROCARBONS ZN CASRBJULTLNT.1.~011 THBRMALDEso close together (137' and 1 4 1 ~ )and the analysis would have shown a very high per cent of bromide for t h e propylene fraction, whereas i t corresponded exactly with the calculated [acetylene tetrabromide, To 100" C . . . . . . . . . . . . . . . . . . . . . . 6.9 1.112 1 O O O t o 115" .................... 2.7 9 2 . 7 per cent bromine; propylene bromide, 79.2 per 1 1 5 * t o 1 2 9 * .................... 5.8 ?:ai0 cent: found 79.9 per cent]. 129'to 132' .................... 38.0 2.liR 132Oto L 3 5 O .................... 10.4 2.100 T h e method of procedure followed in the above Residue ........................ 16.2 ... Tetrabrombutane.. ............. M. P. 116' ... thermal decomposition was quite satisfactory except ANILYSISoe BXOMIDKSISOL*THI) %**OM ABOVS PRIEI~DNS as t o speed. I n order t o obtain larger amounts of Calculated " FD**"l* Per cent BE Found tar" without undue waste of t,ime, a larger apparatus C.H.BI* .......................... 85.1 85.1 was necessary, especially since the supply of t h e OXaBn .......................... 79.2 79.9 CIHIB~........................... 85.5 85.4 propane-butane fraction became exhausted, and i t the lou-er ones, hut i t was found impossible t o separate was found almost impossible t o replenish owing to them, as, above r 4 0 Y , dccomposition would set in, financial difficulties of the company which originally supplied it. T h e only available supply of natural gas condensate available in quantity gave a much smaller yield owing t o the presence of large amounts of ethane. For the apparatus two things were essential; a heating device, and a n electrical t a r precipitator. We were forlunate in finding already set u p the electrically heated furnace previously used by Whitaker and Alexander,' and Whitaker and Leslie;z this was loaned t o ns by the Department of Industrial Chemistry of this Unirersity. A Cottrell t a r precipitator was set up f o r us by the Rescarrh Corporation of this city. MATEKIAL-'~he material used was natural gas condensate from West Virginia in containers under 800 t o 1200 lbs. gressurc. The material being commercially used for lighting purposes came in cylinders built on the principle of a soda syphon, with a deiivery tube reaching nearly to the bottom so as t o insure a gas of constant composition. T h e higher boiling hydrocarbons would thus be expelled along with the lower boiling ones, whereas they would remain as liquids if only evaporation were resorted to. These higher boiling hydrocarbons consisted mostly of pentanes, and as we were not interested i n their decomposition, the cylinders were turned upside down s qIa s t o secure only the fractions containing the butanes, propane, and ethane. When nearly empty, the coolvm. I ing produced by the rapid evaporation would bring and even on distiliation in uacuo liydrobroniic acid the pressure in these cylinders to almost 0, and the and bromine vapors would be given off so copiously flow of gas would stop, h u t if allowed t o stand till that further investigation of this point was abandoned. warmed to room temperature, t h e pressure would rise No acetylene tetrabromide could be obtained b u t a again t o 30-40 lbs. showing t h a t even in the residue, small amount of dibrom benzol was obtained from the a considerable proportion of butane was left. The bromides showing t h a t some benzene would remain high initial pressure in the cylinders would indicate in the gases after the deposition of t h e tar. This, of the presence of methane in t h e first fractions t h a t course, is t o he expected since the gases were cooled came over. This, however, was of no importance as only t o o O , a t which temperature the vapor pressure a t the temperatures used methane would be so stable of benzene is still quite appreciable. Had any ap- as t o make the effect of its presence negligible. preciable amount of acetylene tetrabromide (H. P. APPARATUS A N D PROCEDURE-The apparatus iS 137') been present, it would have appeared with shown in photograph (Fig. I) and in diagram (Pig. the propylene bromide fraction ( 1 3 2 - 1 3 5 ~ ) from 11). For reasons explained above, the cylinder of gas which propylene bromide was isolated, and raised was turned upside down and the gas after passing considerably the specific gravity of this fraction 1 THPS i ~ ~ ~ i 1 r(1915), ~ i . , 4a4. [propylene dibromide 1.946 ( I ? ' ) , acetylene tetra* Ibid., 8 (1916). 593.
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through a reducing valve, where the pressure was dropped t o 1-15 lbs., was sent through a dry meter provided with a scale reading to l / ~ cu. f t . The gas was led from there through the furnace by means of a l / d in. iron pipe. The detailed description of the furnace has already been published’ a n d will not be given here. It is essentially the same furnace as used by Whitaker and Alexander, the only alterations being the removal of the prevaporizer which those authors used, and the fitting of a larger condensing apparatus. Essentially it consisted of a carbon tube, I in. inside diameter, 46 in. long, which was used as a resistor in circuit with a 25-volt, so-kw. alternator. By varying the current sent through t h e resistor by means of a rheostat a wide range of temperature could be obtained. T h e resistor was surrounded by a n air jacket and further insulated by a thick layer of petroleum coke so as t o
Vol. 9, No. 5
running through the middle and carefully insulated from direct contact with it.’ The body of the separator consisted of a 4-ft. section of heavy 6-in. pipe set vertically, flanged a t both ends and provided with a piece of 2-in. iron pipe welded t o the body of the pipe two inches above the lower flange. The inside of the welding was thoroughly smoothed so as t o prevent a n y sharp edge of point. This is a n important consideration in electrical precipitation since the object is t o maintain as uniform a field as possible between the two poles and prevent any sparking, which of course would be facilitated by any sharp edge or rough surface. At either end of the pipe section was bolted a Standard 6-in. T, asbestos gaskets being used t o make the connection gas-tight. I n order to avoid the sharp edges of the pipe, a smooth bronze ring, 4 in. internal diameter, was placed between the flanges so t h a t i t projected over the edge of the 220voits.
D C Circuit
ad t o A C Generalor
FIG. 11-DIAGRAMOF APPARATUSU S E D
FOR
THERMAL DECOMPOSITION OF N A T U R A L GAS CONDENSATES
diminish heat radiation. The outside jacket was a section of Io-in. wrought iron pipe cooled b y a stream of water, the electrode holders being likewise cooled as shown in the diagram. The cooling apparatus consisted of two sections of 11/~-in.pipe, each 4 feet in length, water jacketed and communicating through a piece of 3-in. heavy cast iron pipe which acted as a tar collector for t h a t fraction of the t a r which would deposit on mere cooling. T h e finely divided “fog” was then deposited in t h e Cottrell separator. The principle of the separator is very simple. It consists in passing the gases containing t h e finely divided “fog” between two poles maintained a t a great difference of potential. I n this case one of t h e poles was the body of the separator, the other a wire 1
THISJOURNAL, 7 ( 1 9 1 5 ) . 486.
pipe. Through the top of the flange closing the upper T section passed a double-walled quartz tube 1*/2 in. outside, 3/4 in. inside diameter, projecting about 8 in. into t h e T and held in place by means of asbestos packing. The quartz tube was closed a t both ends by sections of rubber stoppers held in place by washers, the whole being tightly screwed to a metal rod running the length of the quartz tube. T h e upper end of this rod was attached t o a high voltage insulator and from the lower end hung a n 8-lb. lead weight held by a NO. 16 bare copper wire. The length of the wire was such as t o bring the lead weight well below the lower end of the pipe section. The purpose of this was t o prevent the current of gases which entered the separator from 1 For details of this process see C o t t r e l l , THISJOURNAL, 8 ( 1 9 1 1 ) . 542; also R o w l e y and W i r t h , Am. Cos Light J . , 101 ( 1 9 1 4 ) . 177.
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impinging on t h e weight and starting it t o swing, thus causing a short circuit. The pipe section n-as grounded and t h e wire and lead weight connected t o t h e negative side of a high voltage apparatus t o Ire described shortly. The speed at which t h e gases were sent through t h e separator was approximately 3 cu. ft. per minute. The gases passed out from this separator perfectly free from t a r ((fog" and either were led out as waste or passed through a scrubbing system consisting of five wide mouth gallon bottles containing each about gal. lubricating oil. The purpose of the scrubbing system was t o remove benzol, toluol, etc.. which were carried along b y the gas since t h e vapor pressure of these substances a t ordinary temperatures is fairly great and t h e t a r deposited in t h e separator n-as already saturated with those compounds. The electrical apparatus consisted of a s-h. p. motor generator operated on t h e 220-volt d. c. circuit of t h e building. The a. c. was stepped u p b y a 5-kw. oil insulated transformer, as high as 50,000 volts according t o t h e coils used. For our purposes we found 35,000 volts quite sufficient. The current was then rectified b y means of a mechanical rectifier run b y t h e motor and therefore in cycle with t h e alternating current produced. The negative side was connected with t h e inside wire of t h e separator, the positive side grounded outside t h e building, t o prevent interference with other electrical apparatus in t h e neighborhood. The high voltage side of the apparatus, including t h e transformer a n d rectifier, were completely enclosed in a wire cage t o guard any one from accidentally coming in contact with t h e highly charged wires. I n the photograph (Fig. I ) t h e front of t h e cage has been removed t o show t h e arrangement inside. The cage was also connected t o t h e ground in order t o prevent any accumulation of static electricity in t h e neighborhood of t h e rectifier. The regulation of temperature was a t first carried out b y inserting a pyrometer through one of t h e peepholes till i t touched t h e inner tube. After a while, however, we could easily determine i t in terms of t h e energy consumed, with a given rate of gas, and also by t h e amount of ((fog" i n t h e gas as they issued from t h e heated tube. T h e temperature used was i n t h e neighborhood of gooo C. The greater the rate t h e greater t h e amount of energy required as shown b y t h e amperes consumed. A rate of I cu. ft. per min. and 350 amperes gave us t h e best result. The rate of gas was regulated b y timing t h e gas going through the meter with a stop-watch. COUPOSITION OF THE T A R
By t h e procedure above described we prepared about kilos of t a r which was distilled in separate portions and fractions collected as shown in Table IT. The fractions obtained as indicated in Table I\- were redistilled and fractions collected every ten degrees if t h e amount warranted. The low percentage of light oil led us t o believe t h a t much of it passed through uncondensed. T h e condensers were at best able t o cool t h e gases t o 2 j oa t which temperature the vapor I I / ~
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pressure of these light oils was considerable. By scrubbing t h e gases after they issued from the t a r separator and distilling the scrubber oil with steam we were able t o obtain from I t o 1*/2 cc. of light oil per TABLEIV-COMPOSITION OF RECOVERED OIL FROM THE THERMAL DECOMPOSITION OF NATURAL GAS CONDENSATE Specific Gravity 1.109 Per cent by wt. Temp. C. T o 170 O ..........
............................
15.1
cubic foot of gas used. Distillation of this light oil, after washing with concentrated sulfuric acid and sodium hydroxide, showed i t t o be composed of benzene, toluene and a little xylene. The specific gravity of t h e benzene thus recovered, after removal of the unsaturated, was low, however, indicating the presence of some saturated straight chain hydrocarbons. P a r t of t h e t a r deposited in t h e cooling pipes a n d was drawn off from t h e t a r collector. Most of it, however, settled i n t h e separator and dripped down into t h e lower T section from which i t was drawn through a valve a t the bottom. TABLEV-AROMATIC COMPOUNDSFROM THERMAL DECOMPOSITION 01 NATURAL GASCONDENSATE M. P. M. €'. B. P. Picrate
40 80- 82; Benzene. ............. Toluene. ............. 107-110 120-130O Xylene, 80' Naphthalene. Acenaphthene 98: 212 ,, Anthracene Phenanthrene. 99.-1000 145; .... Pyrene(?). . . . . . . . . . . . 249 Chrysene.. ...........
.............. ......... .........
........... ........
.... .... .. .. . .
.. ..
149' 160' 138O 145 222O
Identification Nitrobenzene Trinitrotoluol M. P. 8 2 O
Picrate yellow needles Picrate orange needles Picrate red needles Picrate yellow needles Picrate red needles Small white plates
By allowing t h e various t a r fractions t o solidify, pressing out t h e oily matter and crystallizing from alcohol, the following hydrocarbons reported in Table V were obtained. BENZENE-The benzene obtained after several distillations was water-white, boiled constantly a t 8-82 ', melted at 4 ' and showed a specific gravity of 0.879 at 15.5'. By treatment with "03 a n d HzS04 i t gave nitrobenzene. Some benzene obtained from the scrubbing of t h e gas showed all these properties b u t had a much lower specific gravity, 0.873 a t 15.5'. TOLUENE-BY fractional distillation toluene was obtained, boiling a t I O j-I IO', water-white in color, specific gravity 0.864 at 15.5'. By treatment with HNO, and H2S04we obtained trinitrotoluene, M. P. 8 2 O, crystallizing from alcohol in long, slightly yellow colored needles. XYLENES-The xylene fraction being very small, individual xylenes could not be separated and i t was no further identified t h a n b y its boiling point. It probably contained higher benzol homologues, NAPHTHALENE-The naphthalene fraction, 200-2 jO', was considerable. T h e naphthalene itself was readily obtained pure by several crystallizations. It gave a constant M. P. of 80' and t h e characteristic yellow picrate melting a t 149'. Attempts t o isolate diphenyl (B. P. 2 j 0 O ) and the methyl naphthalenes, which probably occur also in this fraction, have thus far proved fruitless. ACENAPHTHENE-From the fractions U p t o 2 8 0 ' no
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definite hydrocarbon was isolated in sufficiently pure condition to warrant its presence being reported. From the 280-300' fraction acenaphthene was readily obtained, crystallizing from alcohol in flat needles, sometimes in. long, which after two crystallizations gave the constant melting point of 95'. The picrate of this hydrocarbon crystallizes in orange needles melting a t 160'. ANTHRACENE-The 305-3 2 5 ' fraction consisted mainly of anthracene with phenanthrene and uncrystallizable oil. This latter was pressed out on a porous plate a n d to separate anthracene from phenanthrene advantage was taken of the much greater solubility of phenanthrene in alcohol. By several fractional crystallizations the two were obtained pure. The anthracene crystallized in transparent flakes with a greenish blue fluorescence, melting a t 212'. The picrate was prepared by bringing together approximately equal amounts of anthracene and solid picric acid into a solution of picric and in alcohol saturated at room temperature and heating till the two had dissolved. On cooling red needles separated which melted a t 138'. PHENAXTHRENE-The iphenanthrene was obtained as described above, by crystallizing from alcohol, in small white flakes melting a t 99'. The picrate was obtained in the form of yellow needles melting a t 145'.
PYREm-The fractions from 320-3 j o o contained such a complex mixture of hydrocarbons t h a t no individual one could be isolated owing to scarcity of material. From the 35j-390" fraction by extracting with benzene, evaporating and crystallizing twice from alcohol, a mixture of crystals was obtained melting about 138". These were dissolved in alcohol treated with picric acid and the resulting picrate after two crystallizations from alcohol decomposed by ammonium hydroxide. T h e free hydrocarbon thus obtained was crystallized four times when a melting point of 1 4 j " was finally obtained. By this time the material had dwindled to a very small amount and no further crystallizations were attempted. Under t h e microscope t h e crystals appeared as slightly yellow rhombic plates apparently free from a n y other crystals. The picrate of this compound is red in color and melts a t 2 2 2 O . This corresponds very closely t o the properties of the pyrene picrate which is given in the literature as very characteristic. The pure hydrocarbon, however, melts a t 149', whereas ours melts a t 145'. From the yellow color i t would appear as if some phenyl anthracene, which crystallizes in the same system, melts a t 152-153' and has the same solubility as pyrene, was present in sufficient amount to depress the melting point. CHRYSENE-From the small fraction distilling over 400°, by treatment with carbon bisulfite, a yellow powdery residue was left. This residue was crystallized from toluol, then treated with alcohol and nitric acid t o remove the color and crystallized twice from toluol when it was obtained in the form of white scales melting sharply a t 249'.
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N o analyses were undertaken of the above hydrocarbons as little is t o be gained from a n analysis in t h e way of identification. Their melting points, t h e boiling points of the fractions where they occur, as well as the properties of the picrates were thought sufficient t o identify them. CONCLUSIONS
The isolation of the above highly complex aromatic hydrocarbons from the t a r obtained by the thermal decomposition of simple, saturated hydrocarbons such as employed here leads t o the conclusion t h a t aromatic formation can take place by building u p of the ring compounds from low molecular weight hydrocarbons which need not be higher t h a n two or three or fourmember chains. Indeed Meyer and his co-workers' have isolated from the t a r obtained b y the thermal decomposition of acetylene, a large number of aromatic hydrocarbons. Whether the mechanism of the reaction is such as to go through acetylenes or by first building up naphthenes then splitting hydrogen, will not be considered a t present. I n a recent paper by D. T. Jones2 the writer favors the theory of the splitting of hydrogen from naphthenes or from side chains. The objections of the acetylene theory are t h a t either i t is impossible t o isolate it or only minimal amounts are obtained. This seems t o be borne out by our failure to obtain any acetylene tetrabromide from our gaseous products.3 The similarity between the tar we obtained and t h a t obtained from coal is apparent. I n this tar the only products which are not present are the phenols and nitrogen compounds which of course would not appear, since the original material contains neither nitrogen nor oxygen. S U M MARY
I-The thermal decomposition of natural gas condensate is shown to give from simple t o highly complex aromatic hydrocarbons. Among these the following have been isolated: benzene, toluene, naphthalene, acenaphthene, anthracene, phenanthrene, pyrene and chrysene. II-.4n apparatus is described for readily obtaining these aromatic hydrocarbons from natural gas condensate and the precipitation of the tar ('fog" by the Cottrell process. The thanks of the writers are due t o the Department of Industrial Chemistry of this University, and in particular t o Prof. Samuel A. Tucker, for the loan of their electrical equipment and kind suggestions, and t o the Research Corporation of this city for the setting up of the Cottrell precipitator. Further work upon these topics is now in progress in this laboratory. COLUMBIA UNIVERSITY OF CHEMISTRY DEPARTMENT NEW YORKCITY
Be?., 46 (1912). 1609; 46, 3183; 47, 2765. J . SOC.Chem. I n d . . 36 (1917). 3 . 8 For a review of the literature on pyrogenic reactions see Lomax, Dunstan and Thole, Jr. Inst. Pet. Tech., 8, No. 9. 1 1
