BRITISH CHEMICAL ABSTRACTS
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B.—APPLIED CHEMISTRY
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A PRIL 25 and MAY 2, 1930.*
I.— GENERAL; PLANT; MACHINERY.
H eat tran sm ission in surface feed-heaters.
J. T. M ’In t y r e (J. Roy. Tech. Coll., Glasgow, 1930, No. 2, 241—250).—Results of experiments on tlie rate of heat transmission through a feed-water heater tube as influenced by variation of the pressure and tem pera
ture showed th a t the change in pressure on either the water or the steam side of the tube had no measurable effect. At velocities of 3 ■ 91 and 2 • 88 ft./sec. the change was just noticeable, probably due to a slight increase in tem perature affecting the film on the water side.
The range of tem perature through which the feed water has been heated had a very definite effect on the heat-transmission coefficients; e.g., when heating through the range 55—130° F., and from 130° to 200°, 210°, 220°, 240°, and 250° F. a progressive value was obtained. If, however, the heating was started at 180° F. through any higher range, the values when plotted all formed part of the same curve. The difference is attributed to the expulsion of dissolved air from water heated from lower temperatures with increase in the thermal resistance of the laminar film of water. When the temperature is sufficiently high no more air is evolved, and the bubbles already formed are carried away in a more rapidly moving current and so no longer affect the
conductivity. C . A. Ki n o.
S team storage in relation to the peak-load problem in industrial steam plants. E. 6 . Ri t c h i e
(J. Inst. Brew., 1930, 36, 121—130).—W ith ordinary boiler equipment the steam pressure varies with any attem pt to carry fluctuating demands for steam. This has the effect of making the adjustm ent of the fire bed and draught difficult, and from 10 to 20% of fuel is wasted. The shortage of steam results in increased radiation loss per unit of output, and with open vessels the thermal loss may amount to 15% of the total heat consumption. The fluctuating pressure exerts its greatest effect on the rate of output of the manufacturing units, every drop in steam pressure corresponding to a definite loss of output. The difficulty is overcome by the Ruths steam accumulator, which stores steam during periods of low-load demand and gives it out again during periods of peak-load demand when momentarily more steam is required than the boilers are capable of giving. For steam storage the accumulator is only economical if it is used continuously, but it has the advantage of storing steam over the week-end.
C. Ranked*.
Refrigeration by evaporation and its em p lo y
m ent in the saltpetre industry. M . Wa r n e c k e
(Caliche, 1929, 11, 298—330).—The theory of refrigera
tion by evaporation induced by passing a current of air
t h r o u g h a s o l u t io n is d e s c r i b e d a n d d a t a a r e g iv e n r e l a t i v e t o t h e c o m p o s itio n o f t h e s a l t s w h i c h s e p a r a t e f r o m v a r io u s t y p e s o f s a l t p e t r e l iq u o r s w h e n t r e a t e d b y t h i s
p r o c e s s . H . F. Gil t/b e.
Form ation and growth of crystals. W. E. Gib b s
(iBst. Cheni. Eng., 1930. Advance proof. 16 pp.).—A lecture. The formation of nuclei and the growth of crystals in undercooled melts and supercooled solutions are discussed and the practical applications indicated.
C. W. Gi b b y.
Influence of the p roxim ity of a solid w a ll on the con sisten cy of viscou s and plastic m aterials.
R. K . Sc h o f ie l d and G . W. S. Bl a i r (J . Physical Chem., 1930, 34 , 248—262).—The flow of a plastic material is discussed in the light of the data obtained from clay pastes and glyeerol-water mixtures by using the modified Bingham plastometer previously described (B ., 1929, 153). When it is assumed th a t the velocity gradient at any point in a narrow tube through which a plastic material is flowing depends only on the stress a t th a t point, it follows th a t the mean velocity for a given stress at the wall of the tube is directly proportional to the radius of the tube. Thick soil pastes agree with this, but thinner pastes show marked discrepancies which can be accounted for by assuming th a t the plastic properties are modified in the immediate proximity of the w a ll; this gives increased velocity to the bulk of the material. When this increase is first deducted a viscosity constant independent of tube dimensions is obtained. L . S . Th e o b a l d.
Sim plified Goodrich plastom eter. E. Ka r r e r,
J. M. Da v i e s, and E. O. Di e t e r i c h (Ind. Eng. Chem.
[Anal.], 1930, 2, 96—99).—Softness and retentiyity (and hence plasticity) of rubber stocks are determined in a simplified form of the power plastometer already described (B., 1929, 761). Full details of the apparatus and method of procedure are giveD and typical results obtained with it, e.g., plasticity of various rubber stocks, variation of plasticity with temperature, are tabulated and graphed. The effects of varying the size and shape of the test-piece, the load during compression and recovery, the time of compression and recovery, and lubrication of the test-piece are discussed.
S. S . Wo o l f.
[H ellig com parator for] p H control in various industries. H. Ma g n u s (Chem.-Ztg., 1930, 54, 108—110).—Reference is made to the importance of control of pa values in a number of industries. The
“ Hellig comparator ” is an apparatus of simple design in which the colour developed with an appropriate indicator is matched with a standard by observation
through a prism. P- Ir w i n.
* T h e re m a in d e r of th is se t of A b s tra c ts will a p p e a r in n e x t w eek's issue.
351
B r itis h C h e m ic a l A b s tr a c ts —B .
352 Cl. I .—General ; Plant ; Machinery. #
T em perature control of exotherm ic gas reaction s.
0 . Ro e l e n (Brennstofi-Chem., 1 9 3 0 , 1 1 , 68—-70).—The maintenance of the desired reaction temperature in exothermic gas reactions involves the rapid removal of the excess heat developed and the avoidance of tem perature fluctuations within the reaction chamber.
The excess heat may be carried away by the gases themselves, the rate of removal being controlled by suitable dilution of the reactants, or by the use of a cooling fluid, e.g., air, metals of low m.p., water under pressure. Temperature fluctuations may be avoided by subdivision of the contact space and uniform distribution of the gases therein. The concen
tration of the active catalyst may also be varied in the direction of the gas flow, or a certain quantity of the reaction product may be added to the gases in order to control the rate of development of heat. Accurate temperature control is particularly necessary in the Fischer-Tropsch benzine synthesis, in which the heat of reaction is high. A. B. Ma n n i n g.
Reagents for gaseou s im p urities in technical ga ses. E. A. J. H. Nic o l a s (Chem. Weekblad, 1930, 27, 103—104).—Silica gel impregnated with a solution of an appropriate reagent affords a much more sensitive medium for detecting impurities in a gas than the usual absorbent paper, owing to the increased concen
tration of the gas and its attendant impurities on the surface of the gel. H. F. Gi l l b e.
Graphical solution of problem s involving solvent recovery by scrubbing. I. L. Mu r r a y (Ind. Eng.
Chem., 1930, 22, 165—167).—In the nth plate of a scrubber, if X and Z = mol. fractions of the more volatile components in the liquid and gas, respectively, O and IF = the mols. of liquid entering and leaving the scrubber, and P = mols. of gas leaving the scrubber, then Zn = X n + 1 W /{(W — O) + P} + ZpP /{(W — O) + P }. The less volatile liquid approximately obeys R aoult’s law Z = P A X jD (D — total pressure, P a — vapour pressure), whilst the more volatile liquid obeys Henry’s law Z = S P AX /D , where S is an experimentally determined variable. A method is given for the graphical determination of S for each value of X from the liquid-vapour curve a t the b.p., and an example of the solution of a problem involving the recovery of acetone from air by water-scrubbing is added.
C . Ir w i n.
Burner design in furnaces. Se i l a n d o t h e r s .— S e e
II. Creep of steel under stress. Ba i l e y.—S e e X.
Determ inations of particle size. Du n n.—S e e X III.
Pa t e n t s.
Annular kiln. H. Ko r p e r s (G.P. 457,413, 21.11.24).
— F i x e d w a lls , p r o v i d e d w i t h r e g u la b le a p e r t u r e s , a r e s u s p e n d e d a t i n t e r v a l s a lo n g t h e h e a r t h o f t h e k i ln , w h i l s t t h e f ir in g p o i n t s o n t h e h e a r t h a r e b o u n d e d o n o n e s id e b y p r e f e r a b ly s t e p p e d s t r u c t u r e s a n d o n t h e o t h e r b y m o v a b l e p e r f o r a t e d p l a t e s w h i c h l e a n a g a i n s t t h e m a t e r i a l b e in g h e a t e d . T h e l a t t e r t h u s n e v e r c o m e s i n t o c o n t a c t w i t h t h e f u e l. S . K . Tw e e d y.
[B oiler] furnaces. J. N. D. He e n a n (B.P. 3 2 5 ,3 9 0 , 1 8 .2 .2 9 ) .— A w a t e r - c o o le d w a ll o r flo o r f o r t h e c o m b u s t i o n c h a m b e r o f a b o ile r is c o n s t r u c t e d o f s te e l
tubes upon which are shrunk cast-iron rings formed with longitudinal and circumferential fins. After the erection of the wall it is coated with refractory material by means of a cement-gun, in such a quantity th at at least the inner surface is flat. The fins on the metal afford a good key and distribute the heat so th at it is transm itted through the whole circumference of the steel tubes. B. M. Ve n a b l e s.
M eans for indicating d en sity and change of d en sity [electrical conductivity] of fluid in evapor
ators, boilers, and other v esse ls. W . C. Cr o c k a t t,
and W. Cr o c k a t t & So n s, Lt d. (B.P. 325,277,16.11.28).
—A pair of insulated electrodes are inserted through the wall of a pipe or vessel and connected to a supply of power and to an ammeter, which is graduated in density instead of amperes. The parts of the electrodes in contact with the liquid are coated with non-corrosive material, e.g., platinum. B. M. Ve n a b l e s.
H eat-exchangers. Sc h j u d t’s c h e He i s s d a m p f-Ge s.
m.b.H. (B.P. 307,068, 21.2.29. Gcr., 3.3.28).—A heat- exchanger having several groups of tubes arranged in series has headers which are relatively movable to allow for expansion and only one (either the inlet or outlet), is fixed in relation to the casing. The last but one header is connected directly to the outlet header by a small pipe to act as a by-pass for condensate. Other preceding headers may be similarly connected.
B, M. Ve n a b l e s.
H eat-exchanger. W. D y r s s e n , Assr. to Bl a w- K n o x C o . (U.S.P. 1,741,225, 31.12.29. Appl., 31.12.27).
—Two groups of discs of heat-absorbing material are assembled on and rotated by two parallel shafts which are a t such distance apart th a t the discs will intercalate, the discs of one pile forming the spacers for the other pile. The discs extend through the walls of a single inner conduit to a pair of outer conduits carrying the other fluid, and both fluids flow a t right angles to the shafts through 'the spaces between the discs, the inter
calation and extra baffles being placed a t the centre of the inner conduit to prevent flow round the edges of the discs. B. M. V e n a b l e s .
Manufacture of heat-exchange apparatus. E. F.
A. D . Beck (B.P. 304,272, 18.1.29. Belg., 18.1.28).—
After an apparatus comprising a number of ribs or plates threaded over tubes has been subjected to an ordinary internal pressure, with the object of fixing the ribs in place, a super-pressure is applied which is great enough to swell the tubes in the zones where they are not supported by the ribs. The result is th a t the tubes are shortened and the upturned edges or other devices which are provided to act as spacers for the ribs are drawn tightly together and the unit becomes a stiff girder instead of having merely the . strength of the
tubes. B. M. Ve n a b l e s.
Crushing and disposal of furnace residues and other solid m aterials. As h Co. ( Lo n d o n), Lt d.
From F. B. Al l e n (B.P. 325,422, 18.5.29).—The mate
rial is crushed and delivered to a hopper by means of a pair of rolls, then sluiced periodically through the outlet of the hopper by jets of water, and is water-borne to the place of disposal. The rolls are cooled by water applied
B r itis h C h e m ic a l A b s tr a c ts — B .
Cl. I I . — Fu e l ; Ga s ; Ta r ; Mi n e r a l Oi l s, 363
to the parts of their circumference away from the nip, but this water is prevented as far as possible from mingling with the dry material in the hopper and is led direct to the outlet. B. M. Ve n a b l e s.
Continuous m ix in g m achine. H . K . Wi l d e r, Assr. to Ke l l o g g Co. (U.S.P. 1,741,176,31.12.29. Appl., 30.10.26).—An annular stream of comminuted solid is allowed to fall into a centrifugally produced mist of a liquid. The apparatus, which is suitable for pre-mixing the feed to a colloid mill, comprises a high-speed, inner, hollow shaft carrying a spraying device for the liquid a t its lower end, and a surrounding lower-speed shaft carrying a distributor for the solid m atter which works in conjunction with a stationary hopper and sleeve and drops the material just above the liquid spray. The rate of supply of both materials is regulable.
B. M. Ve n a b l e s.
T reatm ent of continuously-m oving m aterial.
C. R. We i h e, Assr. to C. We i h e (U.S.P. 1,742,110, 31.12.29. Appl., 9.7.27).—In processes such as the neutralisation of waste liquors a soluble solid is added to the liquid and the mixture is caused to cascade while the undissolved solid is continuously dragged counter- current by suitable means, thus preventing its escape in the outflowing liquid. Au apparatus shown comprises an inclined rotating cylinder with internal helical rib.
B. M. Ve n a b l e s.
Continuous settlin g apparatus. S. I. Bousman, Assr. to Do r r Co. (U.S.P. 1,741,498, 31.12.29. Appl., 29.3.28).—The rakes of a traction thickener are caused to sweep the corners of a non-circular tank by permitting the inner end of the rotating truss to reciprocate hori
zontally upon the central support, the traction motor on the outer end of the truss following a track which agrees with the contour of the tank, e.g., square, with round corners. The central support preferably takes the form of a pillar upstanding from the bottom of the tank, thus obviating any fixed girder and reducing the loss of head and lift of sludge pumps from tank to tank, when there are several in series, because both feed-inlet and clear overflow may be below the traction rail on opposite sides of the tank. The pillar is surmounted by a cap or ring which simply rotates and carries, on trunnions, a frame which has four or more flanged rollers upon which the inner end of the upper boom of the truss or traction arm is supported. The main part of the floor may be level and the rakes for this portion are suspended from the traction arm in the usual m anner;
the central portion of the floor is sloping (conical), and is dealt with by a number of raking arms suspended from the rotating ring, but the primary object of the recipro- rotating rakes is to cover the corners, and the sloping floor may be extended even to the wall of the tank, being dealt with still by the rotating rakes. There are no bearings below water-level, and the thick sludge is pumped away from the centre in the usual way.
B. M. Ve n a b l e s.
S ynthesis o f chem ical su bstances. M . Po l a n y i
and S. v o n Bo g d a n d y (B.P. 293,302, 21.6.28. Ger., 2.7.27).—One (liquid) reagent is distilled on to a rapidly- moved surface, upon which the other reagent (or reagents), previously activated by radiation or otherwise,
is made to impinge. Disturbances due to the action of the activating agent on the liquid reagent are thus
avoided. C. Ho l l i n s.
Filter. K. F. Pi e t z s c h, Assr. to Se l d e n Re s. &
En g. Co r p. ( U .S .P . 1,741,334, 31.12.29. Appl., 7.6.28).
—A closed chamber, preferably cylindrical in plan, is provided with a filter bottom and over it are rotated, a number of ploughs, or combined ploughs and rollers, so shaped th at when running in one direction they compact the cake, and on reversal dig it up and discharge it through doors in the wall of the chamber.
B . M. Ve n a b l e s.
A ir filter. R . Ir v i n ( U .S .P . 1,741,367, 31.12.29.
Appl., 5.11.26).—A number of louvre-like plates are attached to a pair of endless chains which run vertically and dip into a bath of liquid when turning round the lower sprockets. The air passes horizontally through both rnns of plates, which are V- or W-shaped in order to render the course of the air devious.
B . M. Ve n a b l e s.
T reatm ent of liquids with gases. H. and J.
Sc h e id e m a n d e l (G.P. 460,612, 20.5.24).—The gas is passed into the liquid through narrow, vertical tubes from which only a rapid train of fine bubbles emerge which do not coalesce. Good circulation of the liquid is thus induced. A. R . Po w e l l.
R otary furnace. C. B. Wi s n e r, Assr. to Co a l Pr o c e s s Co r p. ( U .S .P . 1,748,815, 25.2.30. Appl., 13.1.25).—See B.P. 246,118 ; B„ 1927, 431.
R otary retort. W . R. Hu m e (U.S.P. 1,748,178, 25.2.30. Appl., 25.9.24. Austral., 12.10.23).—See B.P.
250,302 ; B., 1926, 520.
D isintegrating m achine. E. Ro t h (U.S.P.
1,748,679, 25.2.30. Appl., 4.1.26. Ger., 16.2.25).—
See B.P. 247,526 ; B., 1926, 471.
Absorption refrigerating m achines. Si e m e n s- Sc h u c k e r t w e r k e A.-G. ( B .P . 304,762, 28.12.28. Ger., 26.1.28).
Continuous absorption refrigerating m achines.
Si e m e n s-Sc h u c k e r t w e r k e A.-G. (B.P. 306,506, 8.2.29.
Ger., 22.2.28).
R otary refrigerators. A.-G. Br o w n, Bo v e r i &
Ci e. ( B .P . 301,871, 29.11.28. Ger., 7.12.27).
M echanical w ork from coal (Swiss' P. 123,928 and 124,135).—See II. Laminated products (B.P. 301,428).
—See V.
II.—FUEL; GAS; TAR; MINERAL OILS.
S m ok eless fuels. P. We i s s (Chim. et Ind., 1930, 23, 3—14).—After references to anthracite and high- temperature coke, three iow-temperature carbonisation processes are described. The Ab-der-Halden process works with a fuel bed 10—15 mm. thick and carbonisation only requires a few minutes. Two rotating hearths are used : in the upper one the coal is dried by contact with combustion gases ; the lower one is indirectly heated. The semi-coke is obtained as a powder. Both gas and solid fuel are used for heating. Little or no dust is carried forward with the gas, and the tar, with a free carbon content of 3-5% , does not emulsify with
B r it is h C hcrnical A b s tr a c ts— B•
:i,r>t Cl. I I . — Fu e l; Ga s; Ta r; Mi n e r a l Oi l s.
water. On a large scale it is intended to separate the operations of drying and carbonisation. The K.S.G.
process is distinguished by its method of temperature regulation employing a circulation of cooled gases of combustion around the drum. Coal dust is used and the products are 82% of coke. 5*3% of tar, 0-4% of “ ben
zine scrubbed from the gas, and 85 cub. m. of rich gas per ton. The coke is fairly hard and contains only 0• 3%
of volatile matter. A process in operation a t Noeux carbonises ovoid briquettes with steam superheated to 650°; the exhaust steam is used in turbines. After passing the primary and secondary condensers, the gas is used in the superheaters. A battery of 20 retorts is used which are heated systematically. The internal heating is stated to give accurate control and better yields, and partial hydrogenation of the heavy oil occurs.
Tar acids are recovered from the aqueous condensate.
Low-temperature tar treated by the usual methods is less valuable than high-temperature tar, and its successful utilisation mav depend on hydrogenation under pressure.
C. Irwix. Study of certain A m erican coals at tem peratures near their softening poin ts. A. M. Ba l l and H. A.
O i'ktis (Ind. Eng. Chem., 1930. 22. 137—140).—The softening points of coal samples were determined by measuring the resistance offered by the heated sample to a current of nitrogen, a thermocouple being embedded in the coal. Results varied from 340° to 440c, and are only approximate. It was found th a t addition of sodium nitrate solution to t he coal greatly modified the pressure- temperature curves, and a similar effect was given by prolonged preheating of the sample. The softening temperature was not varied by working under reduced pressure. The temperature a t which the surface of a single coal particle under a microscope became distorted agreed closely with the softening t emperature determined as above. Experiments are also described on the plasticity of coal a t temperatures slightly below the
softening point. C. It:win.
Chemical studies of peat. 1. W ater in peat.
0 . SjaoxtkoV (Kolloidchem. Beih.. 1930,30. 197 —229).
Determination of the content of moisture, the calorific value-, and chemical composition of peat shows that in these respects peat occupies a position between wood and coal. The examination of peat has led to its definition as a conglomerate of bitumen, hnmic acid and its salts, various other decomposition products of organic m atter through the occlusion of air, and undecomposed struc
tural elements of plants, thus differentiating peat sharply from brown coal. Natural peat c-ontains
$5—M % of •water, part of which can be expressed by mechanical means, the remainder being regarded as oolloidally-bonnd water. The bound water is lost on drying in the same way as in typical hydrogels. The
•water remaining in the air-drv material is regarded as
•water of adsorption and varies between 34 and 43%.
A study of the effect of various coagulating agents on aqueous suspensions of peat has shown th a t colloidal ferric hydroxide is th e most effective agent.. Relativelv
■concentrated solutions of aluminium sulphate a.Te also effective, and gypsum is effect ive at lower concentrations.
E, S. He m e s.
N ational [Italian] lig n ites : F u sib ility of the ash . C. Ma z z e t t i (Annali Chim. Appl., 1930, 20, 3—18).—Compositions of a number of Italian lignites and their ashes, and the m.p. of the latter, are given. The value of the ratio (A120 3 - f S i0 2) : (Fe20 3 + CaO - f MgO) gives no indication of the fusibility of the ash, which must be determined directlv. The fusibility of the ash and the composition are given for mixtures of the lignites with imported coals. T. H. Po p e.
O btaining and preparing average sam p les of solid m ineral fuels. G. N. Be z r a d e c k i (Izvestia Teplotech. Inst. Moscow, 1929, No. 9, 35—40).—On the basis of experimental data, recommendations are made concerning the sampling of coal and coke. T. H. Po p e.
Heat evolved on the treatm ent of different varie
ties of coal w ith concentrated sulphuric or nitric acid. D. J. W; Kr e u l e x (Bremistoff-Chem., 1930, 11.
41— 43).—-The temperature rise on adding 0-5 g. of coal to 10 c.c. of 95% sulphuric acid or 50% nitric acid was measured in a calorimeter of the type used by Burstm and Winkler (B.. 1929, 667). The fairly regular increase in the heat evolved, from about 30 to 120 g.- cal./g., with increasing volatile content of the coals used, on mixing them with nitric acid, indicated th a t it was mainly the volatile constituents which were undergoing oxidation. The results with sulphuric acid were much less regular, oxidation with this acid probably involving the other coal constituents as well. Of the banded constituents clarain and vitrain showed the greatest, heats of oxidation, and fusain the least.: the values for the last-named were similar to those obtained with wood charcoal. The heat of oxidation by acid was increased by a limited preheating of the coal in air, b u t was again decreased by a more vigorous preheating.
A. B. Ma x x ix g.
D istribution of carbon, hydrogen, nitrogen, sulphur, and oxygen in the hydrogenation products of an eocene brow n coal. I. vox Makray (Breim- stofi-Chem., 1930. 11. 61—64).—By hydrogenation of the coal (2200 g.) in the presence of ferric oxide (330 g- in a 20-litre autoclave a t 470:’ (initial hydrogen pres
sure 110 atm .), 45-2% was converted into oil. Oi the carbon introduced into the system 53-4% ap
peared in the oil. 21-7% in the gas, and 24-6% in the residue: 29-S% of the total hydrogen appeared in the oil, 21 *8% remained unchanged in the gaseous form, and the remainder was distributed among the water formed, the gaseous hydrocarbons, and the residue. The yield of water of decomposition was smaller than th a t obtained by direct carbonisation a t 500°. 96-7% of the total sulphur content of the coal (4-23%) was taken up by the ferric oxide. 41 -0% of the nitrogen of the coal appeared as ammonia and 31 - 4% as bases in the oil. Of the total oxygen 4-6-0% appeared as carbon dioxide, 35-6% as water, and 15-5% as phenols in the oil.
A. B. Maxxixg. P la ssm an n p rocess of low -tem p erature car
b onisation . D. B ro w x u e (Brennstoff-Chem... 1930, 11, 44— 46 ; cf. Plassmann, B., 1926, 228: 1927. *>44 : 1928. 395. 631).—Some details are given of the plant a t present under construction at Barking. I t com prises three units and has a daily throughput of about
B r itis h C h e m ic a l A b s tr a c ts —B .
Cl. I I . — Fu e l ; Ga s ; Ta b ; Mi n e r a l Oi l s, 355
66 t o n s . A w a s h e d c o k in g c o a l o f le s s t h a n 5 —6%
a s h c o n t e n t is t o b e c a r b o n i s e d ; t o t h i s m a y b e a d d e d
25% o f w a s h e d a n t h r a c i t e d u f f o f le s s t h a n 2% a s h c o n t e n t . The c o k e w ill b e s o ld a s a d o m e s tic s m o k e le s s
fu e l. A. B. Ma n n i n g.
N ature of the coking process. F . F i s c h e r (Breim- stoff-Chem., 1930, 11, 64—66).—The separation of the oily and solid bitumen from coal and the part played by these constituents in the coking process are briefly described. A distinction is drawn between the primary coking due to the melting and decomposition of the bitumen content of the coal, and the secondary processes due to the condensation of ta r on the cooler parts of the charge and the subsequent coking of the mixture of coal and ta r so produced (cf. B., 1930, 128). The influence of pressure on the coking process is also briefly
discussed (cf. B., 1930, 172). A. B. Ma n n i n g.
H eat econom y of coke ovens. K. Ba u m (Brenn- stoff-Chem., 1930, 11, 47—51).—The accurate deter
mination of the heat efficiency of a coke-oven battery is discussed and a method based on the observation of the heat losses from a single oven is described (cf.
Baum, Gliickauf, 1929, No. 23—25). The efficiency can be increased by a wider use of the regenerative principle, by decreasing the amount of excess air used, as far as th a t is possible, by improved heat insulation, and by increased uniformity in the carbonisation of the charge. From the efficiency of a single oven (r^) that of the battery (•/)) can be calculated from yj '== VjYv where \ \ and V are the heat consumptions per kg. of coal carbonised for the single oven and the battery, respectively. V alone is no measure of the value of the oven design. A. B. Ma n n i n g.
D eterm ination of the calorific value of solid substances. W. A. Ro t h (Brennstoff-Chem., 1930, 11, 46—47).—Paraffin oil is recommended as a secondary standard for the determination of the water equivalent of the calorimeter etc. ; moreover, the addition of a few drops to substances which are difficult to ignite or cannot easily be compressed into pellets greatly facilitates their combustion in the bomb. Such a secondary standard (“ Tested paraffin oil for calorimetric purposes ” ) of cal. value 10,990 i 2 g.-cal./g. can now be obtained from Schering-Kahlbaum A.-G., Berlin. A. B. Ma n n i n g.
D eterm ination of calorific value of bitum inous coals w ith high volatile m atter content. N.
Tschizhevski and M. V erkhovtzev (J. Russ. Met.
Soc., 1927, No. 1, 93—101).—The calorific value of coal containing more than 40% of volatile m atter can be calculated ( i 5—6%) from the equation Q = 82C + aV, where C is the percentage of non-volatile, ash-free, coal- substance, V is the percentage of volatile substances, and a is the calorific value of the volatile substances.
Analyses to determine the value of a were made. The equation is inapplicable to brown coal.
Ch e m ic a l Ab s t r a c t s.
Determ ination of nitrogen in organic substances by hydrogenation. V. F. Op o t z k i (J. Chem. Ind., Russia, 1929, 6, 532—533).—For the determination of nitrogen in coal and coke, ter Meulen’s method has been modified. An iron combustion tube is employed, and the sample is mixed with equal parts of sodium hydroxide
and carbonate. A burette delivers small quantities of water, as required, to the incoming hydrogen. The results for bituminous coal are considerably higher than those obtained by the Kjeldahl method.
Ch e m ic a l Ab s t r a c t s. :
Quick and accurate m ethod of determ ining m oistu re in coal and coke. A. Th a u (Gas World, 1930, 92, Coking Sect., 24—25).—15—20 G. of the sample, of grain size not exceeding 3 mm., are boiled with 100 g. of absolute alcohol, for 2 min., the mixture is filtered, and 25 c.c. of the filtrate are transferred to a test-tube containing 25 c.c. of petroleum. The tempera
ture at which turbidity occurs on cooling is noted, and the moisture present in the original sample is then calculated, using data obtained from standard tests.
C. B. Ma r s o n.
M oisture content of carbon blacks. W. B.
Pl u m m e r (Ind. Eng. Chem. [Anal.], 1930, 2, 57—58).—
The results of a series of experiments indicate th a t the
“ additional moisture ” shown by the xylene-mineral oil method is not in fact present as such in the carbon black, but is formed by the reaction of the mineral oil with the oxygen adsorbed on the black. S. I. Le v y.
D ry purification of [coal and producer] gas.
(i) E. Ka u d e l a (Gas- u. Wasserfach, 1930, 7 3 ,110—112).
(ii) G. Of f e (Ibid., 164—165).—(i) The operation of the purification plant a t the Leopoldau gasworks near Vienna is described. The plant is arranged in series of four purification chambers, the coal gas and the producer gas being treated in separate series of chambers.
The pipe lines are so arranged th at it is possible to pass the gas into the individual chambers either in the middle or a t the top and bottom, and these directions are changed every few days so that the mass is more efficiently utilised than if the gas is always passed in the same direction. The chambers, which are 12 m. long, 9 m.
broad, and 2-2 m. deep, contain six layers of purifying material, each being 16—18 cm. thick. The new material contains about 25% Fe (47-5% of non-volatile matter), 45% H 20, and 7-5% of other volatile matter, and the completely used material 34% of non-volatile residue, 12% H 20, 45% S, and 9% of other volatile matter.
The spent mass from the producer-gas purifiers contains only 20—25% S, and is used further in the purification of coal gas. The final spent mass from the coal-gas chambers by operating in the above-described manner contains 6—9% of Prussian-blue and the gas supplied to the town contains 6—10 g./lOO m.3 of hydrogen cyanide and 1-5 g./lOO m.3 of hydrogen sulphide. The average life of the purification mass is 14—16 months.
(ii) • A discussion of Kaudela’s paper (preceding). If, when a purification chamber is refilled with new iron oxide, the crude gas is passed through this chamber for some days as the first of the series and the chamber is then made the last, much more efficient removal of hydrogen cyanide is obtained, the effluent gas from the chambers then containing only 1 g./lOO m.3 of cyanide, when they have all been treated in this manner. Addi
tion of ferrous sulphate to the contact mass adversely affects the absorption of sulphur. A. R. Po w e l l.
Chem ical reactions in the Petit process [of gas purification]. W. Te r-Ne d d e n (Brennstoff-Chem.,
B r itis h C h e m ic a l A b s tr a c ts —B .
356 Cl. II .—Fu e l; Ga s; Ta r; Mineral Oils.
1930, 11, 67—68 ; cf. B.. 1930, 227).—The crude gas is washed with a solution of potassium carbonate which absorbs all th e hydrogen sulphide and part of the carbon dioxide. The higher rate of absorption of the less strongly acidic hydrogen sulphide is attributed to the relatively slow rate of conversion of the dissolved carbon dioxide into carbonic acid, which then reacts with the potassium carbonate, whereas the hydrogen sulphide reacts directly with the salt. The first stage of regeneration in the saturator, represented by KHS — C02 - f U 20 = KHC03 - f H 2S, is also a time reaction. From the equi
librium constant [K H C 0,][H 2S]/[KHS][C02]. which equals2-06—2-3 a t 20°, and the sulphide content of the wash-liquor, the composition of the gases leaving the saturator can be calculated. The fact, however, th a t the decomposition of the potassium hydrogen sulphide begins only after the conversion of the excess carbonate into bicarbonate must be taken into consideration. The hydrogen sulphide evolved may be absorbed by ferric oxide and subsequently recovered as sulphur of a high degree of purity, or may be oxidised to sulphuric acid.
The second stage of regeneration consists in the con
version of the bicarbonate into carbonate by heating.
A . B . Ma x n t s g.
Naphthalene and w ater in [coal] gas. K . Z i m p e l l
(Gas- u. Wasserfach, 1929, 7 3 , 135— 136).—Experiments in the Augsburg gasworks on the cooling of coal gas showed th a t by the use of an ammonia refrigerator combined with a heat interchanger it was possible, by cooling the gas to 0°, to remove the naphthalene as an oil and the water and ammonia as a strong ammonia liquor, leaving 2-7—3-7 g. of naphthalene, 410—490 g.
of water, and 0-2—0-3 g. of ammonia per 100 cub. m.
in the gas, the cost of the process being only 1-48 RM.
for 2000 m.3/hr., which is less than the cost of pumping the condensate from the various sumps in the town.
A. R. Po w e l l.
D eterm ination of the calorific value of a sm all quantity of g a s b y the Union calorim eter. A.
Bla c k x e (J. Sci. Instr., 1 9 3 0 , 7 , 8 4 — 8 9 ).—The chief source of error is the formation of ozone in the generation of the electrolytic gas used as a standard.
C. W. Gi b b y.
Calculation of g a s calorific values by nom ogram . F. Jones (Gas World, 1930, 92, Coking Sect., 31).—
The construction and use of a nomogram for calculating the calorific value of a combustible gas from its compo
sition is described. C. B. M a p .s o x .
C hem istry and p h ysics of the com bustion of gaseou s fuels. B urner d esign and com bustion of fu els in industrial furnaces. G. E. S eil, H. A.
He i l i g m a n, and C. N. Wit h e r o w (Ind. Eng. Chem..
1930, 22, 179—1S5).—The importance of the oxidising or reducing nature of the furnace atmosphere in the burning of bricks and pottery and in metallurgical operations and also the degree of control which can be obtained when using different types of fuel are discussed. Various methods suitable for burning gas on an industrial scale are described and the use of an annular orifice-type burner is discussed. This burner can be supplied with air which is too hot to be compressed. Curves and experimental data obtained
in th e operation of th is burner w ith producer gas, tow n’s gas, and w ith oil fuel are given. H . Ix g l e s o n.
Influence of p ressu re on the ignition velocity of explosive m ixtu res of m ethane and air.
E. T e r r e s and J. W ie la x d (Gas- u. Wasserfach. 1930, 73 , 97— 103, 125— 133).— The rate of propagation of th e flame in exploding m ethane-air m ixtures under varying conditions has been determ ined b y m eans of a tim in g fork and tw o m agnetic circuits a t either end of a measured length of a bomb, th e circuits being broken w hen th e flame m elted tin-foil strips in its path and th e tim e recorded on a m oving band which also recorded th e m ovem ents of th e tuning fork from which th e interval between th e tw o breaks could be m easured. W hen th e gas m ixture contains sufficient oxygen for com plete com bustion of th e m ethane the rate of propagation of th e flame is a t first reduced b y increasing th e pressure, then is hardly affected by further increase of pressure above a definite value, and finally at. very high pressures becom es more rapid again. If insufficient oxygen is present, however, an increase of pressure increases th e rate of propagation of th e flame and also increases th e explosive range, i.e., it causes m ixtures to explode which would be safe a t lower pressures. The m axim um rate of explosion occurs w ith a m ixture containing 10% of methane, and w ith increasing pressure th e rate falls from 6-1 m ./sec. a t 0 atm . to 4 -5 m ./sec. a t 60 a t m .; a t the same tim e th e explosive range broadens from 7— 13% of m ethane to 6-5— 28% of m ethane. A. R . Po w e l l.
E xtinction of ethylene oxide fla m es w ith carbon dioxide. G. W. Jo x e s and R . E. Ke n n e d y (Ind. Eng.
Chem., 1930, 22, 146—147).—The comparative toxicity of a mixture of ethylene oxide (1-8%) and air, used as a fumigant, introduces hazards due to the possibilities of explosions. The upper and lower limits of inflamma
bility of ethylene with air roughly dried with calcium chloride were 3 and 80% by vol. Carbon dioxide had a marked extinctive effect on the upper-limit mixtures with the proportions of 0—2% vols. of carbon dioxide to 1 vol. of ethylene oxide. When the proportions are above 2 : 1 the effect is in more general agreement with th a t of other gases, e.g., methane and ethylene.
A t least 7 -1 5 vols. of carbon dioxide per vol. of ethylene oxide are required to ensure non-inflammability under all conditions at normal temperatures and pressure.
C. A. Ki n g.
P rim a ry industrial tar. J . II. Pe r t e e r r a (Anal.
Fis. Quim., 1930, 28, 137— 145).—A sample of residual ta r obtained from low-temperature carbonisation retorts employing bituminous coal had d f 1 • 1086 and calorific value 9-472 g.-cal./g., and contained m atter insoluble in ether 2-9% , phenols 2 6-8% , basic substances 3-2% , and neutral oil 65-9% ; of the last-named, 21-2% con
sisted of p sly cyclic compounds. H. F. Gi l l b e.
D irect recovery of standard road tars and other tar constituents of coal-d istillation g a ses by fractional condensation. F. C o o k e (Gas World, 1930, 92, Coking Sect., 27— 30).—A fractional con
densation process for the distillation of ta r (cf- B.P.
301,645 : B ., 1929, 120) and its advantages are
described. C . B . M a r s o x .
B r itis h C h e m ic a l A b s tr a c ts — B .
Cl. II .—F u e l ; Gas ; T ab ; M in e r a l O ils. 357
Chem ical nature of the ligh t hydrocarbons recovered b y com pressing cracking gases and their industrial utilisation. D. Ro m o l i-Ve n t u r i
(Annali Chim. Appl., 1930, 20, 18—26).—The hydro
carbons obtained by compressing the gases formed during the cracking of petroleum residues (mazout, fuel oil, etc.) or of the primary tars resulting from the low- temperature carbonisation of lignite pitch, shale, and asphaltic rock, amount to 5—10% of the original material. These hydrocarbons, formed by the pyro- genic reactions accompanying the dissociation of the hydrocarbons of the raw material, consist of diolefines and diacetylenes, and are quite free from the correspond
ing olefinie and aliphatic terms. I t is not possible to obtain, from their halogenated products, alcohols, ketones, and aldehydes of use as lacquer solvents, nor can such products be used as substitutes for tetrachloro- ethane, dichloroetliylene, etc. as they decompose ■when
distilled. T. H. Po p e.
Calculating heat for flashing petroleum hydro
carbons. S. D. Tu r n e r and J. W. Ha r r e l l (Chem.
Met. Eng., 1930, 37, 98—99).—If S = sp. heat of the liquid, s = sp. heat of the vapour, I = latent heat of vaporisation, x = weight fraction vaporised, and Q = heat added during vaporisation, then Q = (I -j- aS) X x — la (S — s) x2, m a k in g certain approximations to render integration possible. A comparison is made between results obtained, using this equation and those given if (1) the changes in gravity of vapour and liquid which approximately ofiset each other are neglected, (2) the liquid is assumed to be heated to the highest temperature and then vaporised, (3) the liquid is assumed to be first vaporised and the vapour heated.
Appreciable errors are introduced by the last two assump
tions. C. Ir w i n.
P rob lem s in the determ ination of unsaturated hydrocarbons in ga ses. II. L im itations in separa
tions b y sulphuric acid. H. S. Da v is and D. Qu ig g l e
(Ind. Eng. Chem. [Anal.], 1930, 2, 39—41 ; cf. Davis, B., 1929, 583).—Errors in certain methods which have been proposed and in some case are still used for deter
mining the separate defines in gases by absorption in sulphuric acid are discussed. The rates of absorption of propene and n-butenes are too close to permit their separation by selective absorption, and gas analyses based on such procedure are misleading. The saturation of 87% sulphuric acid with silver or nickel sulphate decreases its effectiveness for separating ethylene from propene in an Orsat pipette more than one hundredfold.
H . S. Ga r l i c k.
Anti-knock m otor fuels from Pennsylvania oil.
G. Eg l o f f and E . F. Ne l s o n (Brennstoff-Chem., 1930, 11, 91—94).—Motor fuel of high anti-knock value (50% benzene equivalent) can be produced by cracking Pennsylvania oil a t 500° under a pressure of 200 lb./in.2 The yield is over 65% and the production of gas is small.
The cracked distillate is readily refined, the consumption of sulphuric acid being only 1 i lb. per barrel. The plant used in the process is briefly described.
A. B. Ma n n i n g.
Flam e characteristics of “ pinking ” and “ non
pinking ” fu els. G. B. Ma x w e l l and R. V . Wh e e l e r
(Fuel, 1930, 9, 121—129).—See B., 1929, 878.
A nalysis of A m erican crude oils. S. A. Vu i s h e- t r a v s k i (Azerbeid. Neft. Choz., 1929, No. 6—7, 100—
104).
Determ ination of olefine and arom atic hydro
carbons. Fa r a g h e r and others. Separation of phenols from cresols etc. Mi l l e r and Ur b a i n.—
See III. Creosote oil as preservative for tim ber.
Rh o d e s and Ga r d n e r.—See IX. G asoline storage tanks. Pe s s e l.—See X. Lacquer diluents. Br u n- k o w.—See X III. Gas-liquor as fertiliser. Ra u p p.— See XVI.
See also A., Mar., 286, Nature of “ active carbon ”
( Lo w r y). 322, Form ation of petroleum of the naphthene type ( Pe t r o v). 331, Cracking of cyclic hydrocarbons w ith hydrogen at high pressures
( Ip a t i e v and others). T herm al decom position of perhydro-fluorene and -acenaphthene in presence of hydrogen (Or l o v and Be l o p o l s k i). 332, T herm al decom position of coal-tar constituents ( Ko s a k a).
Separation of xylen es (Na k a t s u c h i).
Pa t e n t s.
R etorts, g a s producers, and like apparatus.
Ba b c o c k & Wi l c o x, Lt d., E. G. We e k s, and W . A.
Ri l e y ( B .P . 324,853, 23.3.29).—Coal is fed from a pre
heater to one end of the retort or producer etc., in the form of a ribbon the full breadth of the retort, which is charged by means of a continuously running scraper which scrapes the coal from the charging end and dis
tributes it evenly over the length of the retort. Any fall in the level of the fuel bed due to extraction a t a greater rate than the coal is fed to the retort is utilised to regulate the speed of the extraction rollers, the hydr
aulic driving gear of the latter being controlled by the motion of a float on the surface of the fuel bed. Any excess coal charged to the retort falls through an over
flow channel and is conveyed back to the bunker by means of an elevator. A. B . Ma n n i n g.
Quenching coke. Ba b c o c k & Wi l c o x, Lt d., E. G . We e k s, and W . A. Ri l e y (B.P. 324,852, 23.3.29).—The hot coke while still giving off gas is delivered from the retort directly -into a closed container wherein it is conveyed through a pool of water. The steam and gas are passed from the container to a combustion chamber from which combustion products are supplied to the retort (cf. B.P. 249,236 ; B., 1926, 429).
A. B . Ma n n i n g.
Purification of gas for distance transm ission.
F. Le n z e (G.P. 457,264, 26.6.23).—The gas is cooled to a temperature, e.g., between 0° and —10°, sufficiently low to ensure the complete precipitation of the naph
thalene while still permitting the use of ammoniacal washing water for the removal of ammonia.
A. B . Ma n n i n g.
Com plete rem oval of am m onia from distillation g ases. E. Ch u r (G.P. 457,230, 15.6.27).—The gases are treated repeatedly with saturated and superheated steam, so th a t the gas is repeatedly raised to a higher temperature and the added steam is each time again condensed with the condensate. A. B . Ma n n i n g.
B r itis h C h e m ic a l A b s tr a c ts—B .
35S C l. I I . — F u e l ; G as ; T a b ; MnnaLUG O ils .
M anufacture of e th ji alcohol and other products from coal-distillation g ases. Co j i p. d e Be t h u n e
(B.P. 303.176, 29.12.2S. Fr., 29.12.27).—Ethane and ethylene are removed from coal gas a t —140° to —200° ; the ethylene is then absorbed in sulphuric acid, and the ethane is dehydrogenated at 600—800° to form ethylene, which is condensed in the cooling apparatus. The utilisation of the ethane increases the yield of alcohol
30%. C . Ho l l i n s.
D ehydration of g a s. W . J. Kl a ib e p., Assr. to
Ko p f e r s Co. (U.S.P. 1,710,248, 17.12.29. Appl., 28.8.26).—The gas is brought into contact with a concen
trated hygroscopic solution, e.g., a saturated solution of calcium chloride, a t about the same temperature as the gas, e.g., 27°, in the lower p art of a scrubbing tower, and with a similar solution a t a lower temperature, e.g., 13°, in the upper part of the tower. The concen
tration of the diluted solutions is restored in evaporators and the solutions are then cooled to the required tempera
tures for recirculation in the respective stages of the
process. A. B. Ma n n i n g.
II Purification and bleaching of m ineral oils and other fatty m aterials. G. Mi c h o t- Du p o n t (F.P.
553,33S, 26.6.22, and Addn. F.P. 32,762, 21.12.26).—
(a) The oil etc. is treated with 10% of its weight in sul
phuric acid and, after settling, the partially purified oil is decanted off and treated again with 10% of its weight in sulphuric acid and with 5% of sodium sulphite.
The mixture is agitated, heated at 110—120° with superheated steam, and the oil decanted. A further acid treatm ent may be given if necessary, (b) When the oil contains glycerides of fa tty acids the glycerol is recovered from the acid layer by known methods and the fa tty acid is collected as a scum containing 1—7% of sulphuric acid. This scum is purified by treatm ent with per-salts and the acids are recovered by distillation.
A . P i. Po w e l l.
D istillation of hydrocarbon o ils. H. Wa d e. From
St a n d a r d Oi l Co. o f In d ia n a (B.P. 324,376, 21.8.28).—
H ot residual oil a t 360—100® is mixed with superheated steam a t atmospheric pressure and 480—650°. The mixture is expanded through a mixing device into a wide conduit leading to a chamber maintained a t a pressure of 25-75 mm. The velocity of the mixed oil and vapour in the conduit is 200—600 ft. per sec. and substantial equilibrium of oil and vapour is obtained.
The equilibrium is completed in the large chamber and unvapourised oil runs into a receiver maintained under vacuum. The oil vapours and steam pass to a condenser maintained a t such a temperature th a t the oil is con
densed and passed to a receiver. The steam is carried, through a trap to remove entrained oil, to a condenser, the condensate being received in a vessel under vacuum.
The consumption of steam is 2—10 lb. per gal. of dis
tillate, and 70—80% of the oil is obtained as distillate.
T. A. Sm i t h.
Separation of liquid [hydrocarbon] m ix tu res.
W., L., W., and F. Me r c k(E. Me r c k) (B.P. 300,266, 20.10.28. Ger., 11.11.27).—A mixture of paraffins is added to a liquid which has different solvent powers for the constituents of the mixture. On progressive cooling.
successive fractions are deposited from which oils of different densities may be recovered. Alcohols and chlorinated hydrocarbons., particularly ethyl alcohol and carbon tetrachloride, or their mixtures, are suitable liquids for the purpose. From a lubricating oil of d 0 - 9283, fractions of d 0 - 9344 and 0 • 9398 m ay be obtained in the presence of a 1 : 1 m ixture of ethyl and propyl
alcohols. T. A. Ss i i t h.
Separation of ( a ) hydrocarbon m ixtu res, (b)
liquid m ix tu res, b y fractional d istillation . J . Y.
J o h n s o n . From I. G. F a r b e n i n d . A.-G. (B.P. 324,350 and 324,357, 20.7.2S).—( a ) Mixtures of saturated and unsaturated hydrocarbons, such as benzene and cyclo- hexane, n-pentane and isoprene, can be separated by fractional distillation if first mixed with one of the following liquids or mixtures thereof : ethylene chloro- hydrin, glycol mono- or di-acetate or monomethyl ether, glycerin di- or tri-acetate, lactonitrile, diethyl tartrate, furfuraldehyde, or aromatic bases such as aniline, toluidine. or phenylhydrazine. The liquids which can be separated by this means are characterised by the fact th a t they have closely adjacent b.p. bu t different degrees of saturation. A 4 :1 m ixture of cydohexane and benzene mixed with 70 pts. of ethylene chlorohydrin, on distillation in a column several metres in height at 100
m m . and 25°, gives a distillate consisting of practically pure cf/c?ohexane, the benzene remaining behind in the chlorohydrin. Mixtures of mono- and di-olefines may be similarly separated, (b ) Low-boiling liquids, such as mixtures containing an ether or organic chloride having b.p. below 20°, m ay be separated by fractional distillation under elevated pressure. The separation is facilitated by the addition of a proportion of high-boiling liquid. Thus crude methyl ether, containing m e t h y l
alcohol and water, on fractionation under 8 atm. gives a product boiling within 1° of the b.p. of the pure ether.
T. A. Sm it h.
Conversion of h eavv into lig h t hydrocarbons.
H . Ma r c h a x d (F.P. 63-3,133, 5.8.26).—The heavy hydrocarbons are mixed with carbonaceous materials, and the m ixture is briquetted and coked. The gases evolved are washed with water to remove steam, and the tar, fa tty substances, and hydrocarbons are s e p a r a t e d
in the liquid form b y condensation. A. B. Ma x n in g.
O btaining hydrocarbons of low b.p . from hydro
carbons of h igh b.p. P. Da n d s w a r d t (U.S.P.
I,742,165, 31.12.29. Appl., 23.4.27).—Liqnid hydro
carbons are heated to boiling in a closed still and hydrogen is adm itted into the vapour space above the liquid. A portion of the mixture of hydrogen and hydrocarbon vapours and gases is continuously with
drawn and subjected to a pressure of over 2000 lb./in."
in a number of compressors connected in series ana located within the charge of oil in the still, whereby hydrocarbons similar to natural gasoline are f o r m e d .
The compressed gaseous mixture is discharged into the body of liquid hydrocarbons, thus effectively distributing the heat thereof, which, together with the heat formed by the operation of compression, is sufficient to boil the contents of the still. The vapours and gases are led to a condenser and the condensate is separated from the fixed gases, which are passed through a gas g e n e r a t o r
