British Chemical Abstracts. B.-Applied Chemistry. October 25

(1)

BRITISH CHEMICAL ABSTRACTS

B.—A P P L IE D C H EM ISTR Y

OCT. 25, 1929.

I.— GENERAL; PL A N T ; MACHINERY.

Evaporation at low tem peratures. E . J a n t z e n

and H . S c h m a l f u s s (Chem. Fabr., 1929K 387—391, 399—401).—-An apparatus for the rapid evaporation of liquids under low pressure near 0° has been devised.

The still is of the type previously described (B., 1929, 77), but the vapours are condensed on ice. The temperature and pressure at which various liquids will boil in the apparatus have been calculated. R . C u t h i l l .

A ll-glass evaporator. D. E. O t h m e r (Ind. Eng.

Chem., 1 9 2 9 , 21, 876— 877).— The evaporator consists of seven lengths of 2 - 5 cm. pyrex tubing with return bends welded in place enclosed in an 8-in. pipe forming the steam space. The concentrate trap and receiver is formed of tw o 5-litre flasks welded together and con

nected to an ejector, and the vapour passes to a coil condenser and vacuum pump. I t serves for the con

centration of corrosive liquids, and under favourable conditions gives an evaporation of I lb. of water per

m inute. C. Irw in.

Determ ining the type of an em ulsion. J . E .

CARRiiiRE (Chem. Weekblad, 1 929, 26, 4 1 3—4 1 6 ).—

The differences in refractive index of aqueous liquids and oils may be utilised to determine the type by inspection of the emulsion illuminated from one side in the microscopic field. The method may be applied to any emulsion when the relative refractive indices of the components are known. S. I. L e v y .

M eaning and m easurem ent of plasticity. E.

K a r r e r (Ind. Eng. Chem., 1 9 2 9 , 21, 7 7 0—7 7 3 ).—The author defines plasticity as the susceptibility to and the retentivity of deformation ; hence, a substance has unit plasticity (1 “ pla ” ) if it deforms a definite amount under some standard conditions when a force of 1 kg./cm.2 acts on it for 1 sec. and the whole of this deformation is permanently retained. This conception is analysed mathematically, plasticity being expressed in terms of “ softness ” and '' retentivity.” The range of usefulness of plasticity measurements is indicated and values for the plasticity of some common materials are

quoted. S. S. W o o l f .

M easurem ent of surface tension in the labor

atory and w orks. H. C a s s e i, (Chem.-Ztg., 1929, 53, 479—480).—A modified apparatus for the determination of the surface tension of a liquid by the bubble method comprises a spherical flask connected to a manometer and provided with a short tube inclined upwards and terminating in a cone-shaped capillary opening instead of the usual capillary tube pointing vertically down

wards. The method of standardising and using the instrument is described. A. R. P o w e l l .

837

Pa t e n t s.

Furnace. J. W. Cox, Assr. to 6 . R. M e t c a l f and E. E. W a l k e r (U.S.P. 1,724,455, 13.8.29. Appl., 12.12.24).—A furnace has two combustion and melting chambers, with individual fuel supply and a common stack. Flues and dampers are provided so th a t the waste gases from either melting chamber can pass to the stack either direct or through the other chamber.

B. M. V e n a b l e s .

Heating-furnace apparatus. E. W i r z , Assr. to A.-G. B r o w n , B o v e r i & Co. (U.S.P. 1,723,319, 6.8.29.

Appl., 18.2.26. Ger., 24.2.25).—A furnace, such as one for the heat treatm ent of discrete articles, with heating elements (preferably electrical) above and below the space for the articles, is provided with a number of girders or walls protecting the lower heating elements and spaced apart so th at a number of elements of a lifting carriage may enter the spaces and deposit the goods on the girders, the carriage being withdrawn during the heating. The floor actually supporting the goods may thus be kept as light as possible or even omitted altogether, so th at the heat capacity of the support is reduced to a minimum. B . M. V e n a b l e s .

Gas producer and boiler plant for liquid-heating and/or steam -raising purposes. T. R . W o l l a s t o n

(B.P. 317,189, 30.6.28).—A single gas producer supplies gaseous fuel to a number of boilers and the producer itself is provided with a jacket th a t serves as a water heater. Valves are provided for the independent regu

lation of the gas and fluid supplies to each boiler. In an example all the heaters are connected to one main circulation for hot water. B. M. V e n a b l e s .

Heat exchanger. H . H e n d e r s o n and J. G . G l a s g o w ,

Assrs. to G u l f R e f i n i n g Co. (U.S.P. 1,724,351, 13.8.29.

Appl., 4.9.26).—The tubes of a heat exchanger are ex

panded, a t one end, into a tube plate which is provided with flanges and a cover plate, the space thus enclosed forming the header. The tube plate is not rigidly attached to the casing, but a bellows-like device is attached to the casing on the one side and the cover plate on the other. The tube plate at the other end may be rigidly attached to the casing.

B. M . V e n a b l e s .

Carrying out of gas reactions. 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. 317,996, 29.8.28).—

Vessels used for effecting reactions a t high temperatures between materials in the gaseous phase are protected by adding to the materials small quantities of non- reacting substances non-volatile a t the temperature of the reaction and capable of forming a liquid film on the interior of the apparatus; e.g., 5% of paraffin wax is

(2)

B r itis h C h e m ic a l A b s tr a c ts —B .

838 C l. I .— Ge n e r a l ; Pl a n t ; Ma o h i h k r y.

added to middle oil prior to entry into apparatus for hydrogenation a t a high temperature and pressure.

L. A. C o l e s .

Carrying out endotherm ic chem ical reactions of various kinds. F. K r u p p G r u s o n w e r k A.-G. (B.P.

309,942, 1.6.28. Ger., 18.4.28).—In a process for the volatilisation of metals, for the reduction of sulphates to sulphides, etc., in a rotary tube furnace, in which solid fuel is added to the charge and by combustion with oxygen taken from the materials produces most of the heat required, the additional air and/or gas necessary, the products of combustion, and the charge of material all travel in the same direction in the furnace, thus preventing re-oxidation of the products.

Spray dryers. W. A l e x a n d e r (B.P. 317,166, 9.6.28).

—The air is adm itted in a whirling m anner to the top of a cylindrical chamber, an inner supply of cold and an outer supply of hot air being usually provided; the centrifugal spraying disc for the liquid is also a t the top.

The air is exhausted axially a t the lower part of the cylindrical chamber but above the conical hopper bottom. Conical bafiles surround the air outlet and help to guide the dried dust into the hopper and prevent disturbance of the outgoing air. B. M. V e n a b l e s .

D rying, heating, or cooling m achines. IV. G. and F. R. S im o n (B.P. 317,581, 25.6.28).—A dryer or similar machine, of the type in which a reel with lifting and agitating bars rotates in a casing and surrounds a bundle of tubes conveying heating or cooling fluid, is provided with hammers pivoted on a fixed portion of the machine and raised either by contact with the reel or by separ

ately driven means, which drop upon the reel and keep it free from accretions. B. M. V e n a b l e s .

N on-conducting covering for p ipes. G. T. d e

K l e r k (B.P. 316,202, 24.10.28. Belg., 25.7.28).—

Asbestos with or without air spaces is placed in contact with the pipe, and paper or cardboard, alternately plain and corrugated and glued together, is used for the cooler outer layers. B. M. V e n a b l e s .

T herm al insulation. E. S c h m i d t a n d E. D y c k e r - h o p f (B.P. 317,678, 3.11.28).—*A f o r m o f t h i n m e t a l s h e e t c a s in g a n d s u p p o r t i n g s t r u c t u r e f o r u s e i n c o n j u n c t i o n w i t h i n s u l a t i n g m a t e r i a l , w h ic h m a y a ls o b e c o m p o s e d o f t h i n m e t a l s h e e ts , i s d e s c r ib e d .

Single-roll grinding m ills. A. E. G. M a c C u l l u m

(B.P. 316,907, 5.4.28).—A roller mill with single grinding block is provided with a narrow scraper blade within the feed hopper which removes the material from the surface of the roll after it has passed under the block ; the partly ground material overflows the blade and falls on the roll to be again ground by the same block.

P ulverising apparatus. F. H. D a n i e l s , Assr. to

R i l e y S t o k e r C o r p . (U.S.P. 1,724,072, 13.8.29. Appl., 21.8.26).—-A roll crusher is situated a t the inlet to an impact pulveriser. One roll can yield to permit hard masses to p a ss; these are caught in a special pocket and not admitted to the pulveriser. B. M. V e n a b l e s .

Pulverisation and separation of cereals, m in erals, etc. H. A. L i v i n g s t o n e (B.P. 316,922, 5.5.28).—U p

wardly extending from a disintegrator chamber is an exhaust trunk which is divided by a triangular partition into two conduits up one of which the ground material is flung by the action of the beaters and down the other branch oversize returns to the disintegrator, a separat

ing zone being situated at or near the apex of the tri

angle. A second triangular baffle is situated above the first, forming a second separating device. Adjustable flaps are provided to regulate the action.

Apparatus for pulverising m aterial. W. T.

D o y l e , Assr. to S t u r t e v a n t M i l l C o. (U.S.P. 1,723.726, 6.8.29. Appl., 19.11.28).—In a pulveriser operating w itk two or more stages (such as a ball mill with more than one compartment) and provided with an air separator, the oversize from the separator normally passes for re-grinding to an intermediate stage, but any excess over a certain definite amount passes through another passage to mix with the original feed ; this excess operates a device which reduces the amount of the original feed, preferably by reducing the speed of the motor operating the feeder. B. M . V e n a b l e s .

M eans for concentrating or separating solid substances. A. A. L o c k w o o d ( B .P . 317,141, 15.5.28).

—A sloping imperforate table is reciprocated and is also subject to percussion by means of loosely-mounted devices attached to it. Examples of such devices are balls in boxes, or pendulums operated either solely by the reciprocation of the table or by engagement with fixed tappets to an external rigid support. B . M. V e n a b l e s .

Dust separator and collector. T. S. M o n a g h a n ,

Assr. to G .E. O l m s t e d (U.S.P. 1,723,703, 6.8.29. Appl., 24.5.27).—A cyclone separator is provided with cylin

drical, inverted frusto-conical, and upright conical baffles, intended to improve the separation of dust and to direct the clean gas into the axial outlet.

M ixer. C. W. H o t t m a n n (U.S.P. 1,723,620, 6.8.29.

Appl., 5.5.26).—The mixer is similar, in principle, to a Root’s blower, but with the shafts vertical, and scraping and mixing bars instead of solid impellors.

M ixer. A. C r o s s m a n (U.S.P. 1,724,740, 13.8.29.

Appl., 21.8.24).—A mixer for solid and fluid constituents is constructed so th a t the former enters through an inclined chute above a beater, which rotates in a direc

tion to drag the solid material below the surface of the fluid which is adm itted through a separate pipe. The mixture is exhausted through a separate nozzle.

B . M . Ve n a b l e s.

M ixing m achine. S . S n y d e r , Assr. to S p r o u t , W a l d r o n & C o. (U.S.P. 1,724,808, 13.8.29. Appl., 26.2.29).—Liquid is injected downwardly into the mix

ing mass by means of a hollow arm rotating with the agitator blades and situated above them.

Blending or m ixin g. H. E. V a n d e n B e r g h ( B .P .

317,128, 12.5.28).—The material, such as tea, is charged into an upper chamber having a floor composed of a number of louvre-like slats which are kept closed during the charging but afterwards opened to allow the material to fall into the lower chamber. From the lower chamber

(3)

Ci.. I . — G e n e b a l ; P l a n t ; M a c h i n e r y .

839

the material falls by gravity (under control) to an ele

vator which returns it to the upper chamber. This pro

cess is repeated as desired. B. M. V e n a b l e s .

Centrifugal em ulsifier or hom ogeniser. E. G.

W a i t (B.P. 316,959, 7.5.28).—The material is supplied to the centre of a rapidly rotating dish which is so contoured th at as the centrifugal force increases with increase of radius so also does the resistance to flow of the film of liquid, i.e., the surface of the dish rises with increasing slope outwardly, finishing in some cases with a slightly in-turned edge. The centre of the bowl may be formed in a curve running to a point at the axis to minimise shock at entry. B. M. V e n a b l e s .

A gitating or m ixin g liquids, slim es, etc. H. J.

C o l l i n s (B.P. 317,529, 19.5.28).—Liquid flows from ail upper tank through a regulating valve to an air-tight tank provided with a non-return air-outlet valve and with a float-controlled siplion which empties the air

tight tank rapidly after the liquid has attained a certain height. The liquid may be caught in a lower storage tank and pumped back to the upper one for re-use. The air-tight tank lias one or more pipes connecting with bells or other devices immersed in the liquids to be agitated. While the siphon is operating, a partial vacuum is produced and the liquids will rise in the bells ; on completion of the siphon action air enters the air

tight tank and the liquid in the bells falls suddenly and causes agitation. B. M. V e n a b l e s .

Causing solids to be penetrated by or im p reg

nated with liquids or solutions of various sub

stances. H. J. C o l l i n s (B.P. 317,427, 16.5.28).—The solids (such as hides) are placed in a strong container which is then completely filled with liquid by means of a pump. When a desired mean pressure is reached the reciprocation of the pump is continued, but by opening a by-pass from the outlet back to the pump chamber delivery of liquid ceases, the effect of the pump being to cause pulsations of pressure. The motion of the plunger may be suddenly accelerated towards the end of the delivery stroke. B. M. V e n a b l e s .

Filtering sy stem . R. A u d u b e r t (U.S.P. 1,723,997, 13.8.29. A p p l., 7.3.28. Fr., 27.10.27).—T h e l iq u i d i s f o r c e d t h r o u g h a m a s s o f f ilt e r in g m a t e r i a l h a v in g c a p i l l a r y p a s s a g e s , u n d e r a h e a d o f 5—100 c m . o f w a t e r a n d a t a r a t e lo w e n o u g h t o a llo w t h e e le c tr ic a l s u r f a c e c h a r g e s t o a t t r a c t , t h u s p r e v e n t i n g a n y i m p u r i t i e s f r o m p a s s i n g . B. M. V e n a b l e s .

A ssem bling of filter stack units. V. R. He f i l e r

(B.P. 303,153, 17.12.28. U.S., 30.12.27).—Starting with a ribbon of the filter material, the discs (usually of two alternate shapes) are formed by punching and correctly assembled as a pack by purely mechanical means:

Thickener. E. J. S w e e t l a n d , Assr. to O l i v e r U n i t e d F i l t e r s , I n c . ( U .S .P . 1,724,436,13.8.29. Appl., 24.1.24).—In a vacuum filter, in which the filter elements are submerged in a tank containing the prefilt, the outlet pipe for filtrate and the accompanying vacuum- producing device are below the level of the prefilt iii the

tank. B. M. V e n a b l e s .

Centrifugal separator. J. C. B u c k b e e (U.S.P.

1,724,254, 13.8.29. Appl., 11.4.28).—An approximately spherical bowl has an upwardly-extending, hollow driving shaft and a comparatively large overflow mouth at the bottom. Within the hollow shaft is a feed tube which carries on its lower end two baffles, the upper one to distribute the feed m aterial; the lower, which has apertures near the axis for emission of lighter liquid, is shaped to the bowl and more or less closes the outlet mouth. The tube and baffles are not prevented from rotating with the bowl. B. M. V e n a b l e s .

Centrifugal separator [for sew age etc.]. T . T o h l i n (U.S.P. 1,723,495, 6.8.29. Appl., 25.1.28).—

The material, such as sewage, from which it is desired to separate a proportion of clear water, enters the lower small end of a frusto-conical bowl which is rotated by a shaft extending upwards through the outlet for clear w a te r; the arms connecting the shaft to the bowl serve also to propel the sewage. The thickened sew-age flows over the upper large end of the bowl into a sur

rounding casing and is exhausted downwardly; the clear water leaves axially a t the top through a pipe surrounding the driving shaft, the pipe being provided with a bend through which the driving shaft emerges.

B . M. V e n a b l e s .

Centrifugal separators. A k t i e b o l a g e t Sei.’a b a t o r ( B .P . 306,948, 14.2.29. Swed., 29.2.28).—A sight glass is described for use on a separator of the type which emits dirty feed fluid when the bowl requires cleaning.

Apparatus for w ashing or scrubbing gas. T. A.

C l a p h a m (B.P. 317,412, 10.4.28).—A scrubbing tower is divided into a number of stories, each having a concave tray at the bottom to catch the washing liquid. The liquid is lifted from the tray (of every storey) and spread over the top of the filling in the same storey by means of a centrifugal device attached to a vertical shaft serving all the stories. There may be a continuous feed of a minor quantity of liquid to the top of the tower.

Purification of furnace and like gases. D.

R a d u l e s c u (B.P. 289,825, 2.5.28. Roum., 2.5.27).—

Supersaturated or condensing water vapour is added to the gas, the mixture is subjected to rapid whirling (by which means the collected particles are flung out), and then passed through a centrifugally produced veil of water ; these three steps are repeated as often as may be necessary. The apparatus described comprises an inclined cylindrical conduit through which the gas passes and a rapidly rotating shaft, co-axial with the conduit, provided with a number of radial stirrers. To the odd-numbered compartments thus formed condensing vapour is supplied ; in the even-numbered ones water is directed against the rotating blades. B. M . V e n a b l e s .

A nalysis of gaseous m ixtu res. I / A i r L i q u i d e

Soc. A n o n , p o u r l ’E t u d e & l ’E x p l o i t . d e s P r o c . G.

C l a u d e (B.P. 290,259, 11.5.28. Fr., 11.5.27).—The

apparatus is operated by means of a WoulfFs bottle containing absorption liquid which can be put into communication with a source of inert gas a t moderate pressure, say 500 mm. of water. The gas is blown through and collected in a measuring burette a t atmos

pheric pressure ; the burette is bounded top and bottom

(4)

B r it is h C h e m ic a l A b s tr a c ts —B .

840 Cl. II .—Fu e l ; Ga s ; Ta r ; Mi n e r a l Oi l s.

by capillary tubes, the lower one being always at atmospheric pressure when measurements are being effected. After absorption of a constituent of the gas and return of the remainder to the burette, the latter will be partly full of liquid, and the liquid in the upper capillary (and the gas) will be under pressure less than atmospheric by a depression which is equal to the height of the liquid in the burette. This height is balanced automatically by a depression in a hydrostatic tube which is connected to the upper capillary of the burette by way of the absorption chamber, all connecting passages being full of liquid. This depression is readily indicated by a float in the hydrostatic tube, and the level may be recorded by a stylus operating on a chart which is graduated in accordance with the shape of the burette ; th a t shape is so chosen th a t the upper level of the liquid (after absorption) stays in a narrow but not capillary part of the burette. B. M. V e n a b l e s .

R otary filter or strainer. F. W. B r a c k e t t (U.S.P.

1,726,608, 3.9.29. A ppl, 29.11.26. U.K., 28.10.26).—

See B.P. 284,403 ; B., 1928, 248.

Recovery of reaction products from gases treated w ith electric arcs. 0 . E i s e n h c t , Assr. to I. 6 . F a r b e n i n d . A.-G. (U.S.P. 1,726,547,3.9.29. Appl., 29.12.26. Ger., 30.12.25).—See B.P. 263,859; B., 1928, 415.

R otary refrigerating m achine. M. A u d i f f r e n and A . Singrun (B.P. 299,724, 29.10.28. F r., 28.10.27).

A bsorption refrigerating apparatus. E l e c t r o l u x , Ltd., Assees. of A. Lenning (B.P. 297,057, 12.9.28.

U .S., 13.9.27).

Absorption refrigerating apparatus. H. D. F i t z p a t r i c k . From C. F. M. v a n B e r k e l ( B .P . 317,340, 12.12.28).

M echanical device for regulating the quantity and com position of a gas m ixtu re. I. G. F a r b e n i n d . A.-G. (B.P. 296,063, 23.8.28. Ger., 24.8.27).

Gas w asher (U.S.P. 1,718,988).—See X. H um idity of gases (B.P. 317,306).—See X I.

II.— F U E L ; G A S; T A R ; MINERAL OILS.

Coke-oven heat balances. V. F e o d o r o v (Chim. et Ind., 1929, 22, 231—248).—In considering the heat balance the net thermal effect of the reactions which occur during carbonisation can be neglected as they are within the limits of experimental error. The loss of heat unaccounted for by other observers (cf. B., 1923, 389 a , 436 a ) is considered to be largely due to losses of combustible gas by percolation through the walls of the heating flues and to partial combustion within the oven itse lf; these, in turn, depend on the temperature and duration of the coking process. A tten

tion to these factors indicates the lines along which improvements in coke-oven efficiency may be achieved.

C. J e p s o n .

Correlation of physical and chem ical properties of cokes w ith their value in m etallurgical pro

cesses. II. W. T. K. B r a u n h o l t z , G. M. N a v e , and H. V. A. B r i s c o e (Fuel, 1929, 8, 411—437 ; cf. B .,

1928, 432).—Investigation of the “ Micum ” trommel

test for determining the mechanical strength of coke shows th a t this is essentially a modified shatter test in which the force of impact alone plays a significant part.

Determinations of the volatile m atter in coke give results which vary with the method of carrying out the test, and particularly with the time of heating ; evolution of volatile m atter at 950° continues a t an appreciable rate for a t least 30 min. Marked differences in the weight of coke occupying 1 cub. ft. are observed according to the origin of the coal carbonised and the carbonising condi

tions. Full-scale experiments have shown th at (1) cokes from an uncompressed coal are more resistant to shatter, but have a lower volume weight and a higher porosity than those made from compressed charges ; (2) varia

tions in the width of the oven and the carbonising time have little effect on the quality of the coke ; (3) although samples of coke from different parts of the oven show some differences, tests on samples from the middle of the charge are in good agreement with those on average samples from the same ovens ; (4) “ soaking ” after completed carbonisation slightly lowers the shatter indices and porosities ; (5) blending anthracite with a coking coal may cause an improvement in the shatter test results. A reliable indication of the quality of a coke produced from a given coal under given conditions is obtained by carbonising 1—2 cwt. of the coal in tins embedded in full-scale oven charges of another coal.

The behaviour of a series of cokes in a full-size cupola has been compared. The relative melting efficiencies of the cokes correspond with their relative efficiencies as determined by the “ combustibility ” test. A slightly modified form of the laboratory apparatus has been devised for the latter test, and experiments have Ijeen carried out on the influence of mode of production, ash content and composition, and graded size on the combustibility of coke. A. B. M a n n i n g .

Influence of size of coke on degree of com bustion in front of the tu yères. W. M a t h e s i u s (Stahl u. Eisen, 1929, 49, 1220—1221).—The depth of penetration of the blast into the furnace is chiefly dependent on the number of obstructions which cause deviations in its direction, and hence on the size of the pieces of coke used. The correct size of the coke for any furnace depends on the reactivity of its surface and the rate at which the furnace is run. For the production of white iron, where a rapid rate is required, small coke gives the best results, whereas for the production of grey iron, which is a slower process, larger pieces of coke should be used. A. R . P o w e l l .

Action of iron catalysts on m ixtu res of carbon m onoxide and hydrogen. E. A u d i b e r t and A . R a i n e a u (Ann. Off. nat. Combustibles liquides, 1928, No. 3 ; Ind. Eng. Chem., 1929, 21, 880—885).—

Ferric oxide, unlike reduced iron, yields liquid as well as gaseous products when used as catalyst for the interaction of carbon monoxide and hydrogen a t 150 atm. and 250°. The yield of liquid products quickly falls to zero with the reduction of the ferric oxide. The reduction of the ferric oxide is prevented to some extent by the addition of alkali, or by the use of a gas mixture containing excess of hydrogen. The addition of alkali salts, or copper, is of no benefit,

(5)

C l. I I .— Fu e l ; Gas ; Ta r ; Mi n e r a l O ils. 8 4 1

neither is the use of lower pressures and temperatures practical, nor the replacement of the iron by man

ganese. In all these cases carbon is deposited on the catalyst, and leads to irregular action. Better results were obtained by converting the ferric hydroxide into phosphate or borate by addition of acid, adding a solu

tion of the nitrates of copper and manganese, pre

cipitating as a paste by soda, and then adding potassium carbonate. With this no carbonaceous deposit was formed, and a yield of 15—17% by wt. of organic liquids was obtained. The remainder is gaseous hydrocarbons, carbon dioxide, and water vapour. About two thirds of the organic liquid distil below 180°, this including a laTge proportion of aliphatic alcohols which must be recovered from the aqueous layer. These results were obtained at 380—450° with a space velocity of about 10,000 and at 150 atm. pressure (cf. B., 1928, 920).

C. I r w i n .

Ignition of firedam p b y the heat of im pact of m etal against rock. M. J. B u r g e s s and R. V.

W h e e l e r (Safety in Mines Res. Brd., Paper No. 54,1929, 25 pp. ; cf. B., 1929, 41).—Mixtures of methane and air containing 7 • 5—9 • 0% of methane could not be ignited by the sparks produced on pressing a steel block against a revolving carborundum wheel. The sparks, however, were able to set fire to thin tissue paper, and thereby indirectly to ignite the gas. Similar tests with the sparks produced from steel blocks pressed against a revolving wheel of hard steel also failed to ignite the gas, either directly or by allowing the sparks to fall on tissue paper, oiled paper, or coal dust. The firedamp was, however, ignited by the heated edge of a steel rod pressed against a rapidly revolving wheel made from a hard quartzitic sandstone. Tests under similar con

ditions with wheels made from “ Derbyshire grit ” or carborundum failed to cause ignition. No ignition was obtained in tests made by pressing various hard rocks against a steel disc in the manner of the “ steel mill.”

Tests with a cutting disc produced ignition with certain hard rocks; very little sparking was produced with any of the rocks, ignition being due to a heated area of rock produced by the cutters. Tests with coal-cutter picks set in the circumference of a rapidly revolving wheel caused the ignition of firedamp through the heating of the rock surfaces through which they cut. A chain coal-cutter cutting through hard rock in an experimental chamber filled with an explosive methane-air atmos

phere also produced ignitions. A. B. M a n n i n g .

Extinction of flam es. W. P. .T o r is s e n and B. L.

O n g k i e h o n g (Chem. Weekblad, 1929, 26, 433—436).

—Analyses are given of the gases remaining when various inflammable substances cease to burn in air, and of mixtures of oxygen and nitrogen, and of oxygen, nitrogen, and carbon dioxide adjusted just to extinguish burning materials plunged into them. The literature

is reviewed. S. I. Le vy.

Flash point determ ination. J. T e r p u g o f f (Petrol

eum, 1929, 25, 1161—1163).—The method and appara

tus of Schliiter (B., 1928, 325) have been examined and compared with those of Sommer and Runge and of Marcusson. The Pensky-Martens apparatus (closed flash point) is frequently too sensitive for commercial

heavy oils, since differences of many degrees are often observed in oils which are commercially acceptable as of the same quality. S. I . L e v y .

Iodine values of mineral o ils. ^{B .}M. M a r g o s c h e s , B . K r a k o w e t z , and F. S c h n a b e l (Petroleum, 1929, 25, 1179—1186).—After a critical review of the litera

ture, an account is given of comparative determina

tions, using the Hiibl method, and the more recent

“ rapid ” method (cf. Margosches, Hinner, and Fried

mann, B ., 1924, 640), in which the oil is emulsified with water and an alcoholic solution of iodine. The conditions under which the latter gives the same results as the Hiibl method were determined. The heavier oils cannot be made to emulsify satisfactorily with alcohol alone, and it is therefore necessary first to precipitate asphalt by addition of ether or acetone, and to emulsify the asphalt-free oil with a mixture of alcohol with ether or acetone for the determination ; concordant results, however, could not be obtained with heavy fractions. S . I . L e v y .

E m ulsions of hydrocarbons. M e u n i e r . Effect of hydrogen ions on em ulsions. K r a n t z and

G o rd o n -. Solvents for w axes. P i c k e t t . — S e e X I I . Pa t e n t s. r

Coke oven. M . K e l t i n g (U.S.P. 1,726,494, 27.8.29.

Appl., 13.7.25. Ger., 18.7.24).—A heating chamber for a coke oven has alternate uptake and downtake conduits connected together a t their top and bottom ends, respectively. A burner with an air nozzle is situated a t the lower end of each uptake conduit, and an outlet for discharging part of the products of combustion at the lower end of each downtake conduit.

A. B. M a n n i n g .

Retort ovens for low -tem perature carbonisa

tion. C om p. G e n . d e D i s t i l l a t i o n e t C o k e f a c t i o n

A B a s s e T e m p e r a t u r e e t M in i e r e “ H o l c o b a m i ”

Soc. A n o n ., Assees. of I n t e r n a t . H o l d i n g d e D i s t i l l a t i o n e t C o k e f a c t i o n a B a s s e T e m p e r a t u r e e t M in i e r e “ H o l c o b a m i ” Soc. A n o n . ( B .P . 308,760, 28.9.28. Ger., 28.3.28).—The ovens described in

B .P . 229,880 ( B ., 1925, 245) are made more efficient by subjecting the retorts to indirect heating, i.e., the heating gases are ignited in a separate combustion chamber and the hot gaseous products are passed over the retorts, which are constructed in staggered

formation. C. B . M a r s o n .

Manufacture of fuel. L. K i r s c h b r a u n (U.S.P.

1,725,198,20.8.29. Appl., 14.3.21. Renewed 17.3.26).—

A combustible agglomerate is made by mixing powdered coal with an emulsion containing an argilliferous emulsifying agent and a bituminous base, and then breaking down the emulsion so th a t the adhesive agent binds the coal into the required agglomerate.

A . B . Ma n n i n g.

Complete gasification of fuels. 0 . G r o s s (B.P.

289,080, 15.3.28. G e r., 23.4.27).—F u e l w i t h t h e u s u a l a m o u n t o f v o l a t i l e c o n s t i t u e n t s is g a s if ie d , w i t h o u t p r e v io u s c o k in g , f o r t h e p r o d u c t i o n o f h y d r o g e n o r a g a s m i x t u r e c o n ta i n in g i t s u i t a b l e f o r t h e p r e p a r a t i o n o f s y n t h e t i c a m m o n i a e tc . T h is i s e f f e c te d b y g a s if y in g t h e f u e l i n a m i x t u r e o f o x y g e n ( a n d / o r a ir ) a n d

(6)

B r itis h C h e m ic a l A b s tr a c ts — B .

842 ' C l. I I . — Fu e l; Ga s ; Ta r; Mi n e r a l Oi l s.

w a t e r v a p o u r so t h a t t h e n i tr o g e n c o n t e n t o f t h e r e s u l t in g g a s is n o t g r e a t e r t h a n t h a t r e q u i r e d f o r a m m o n i a s y n t h e s i s ; t h e h y d r o c a r b o n s a r e c o n v e r t e d b y o x y g e n o r o x y g e n a n d w a t e r v a p o u r i n t o c a r b o n m o n o x id e a n d

h y d r o g e n . G. B. M a r s o n .

Gasificación of bitum inous coal. J. M. ^R^{u s b y}^, Assr. to U.G.I. Co n t r a c t in g Co. (U.S.P. 1,725,739, 20.8.29. Appl., 7.6.23).—In a retort for the complete gasification of coal containing a descending fuel bed comprising coal a t the top and coke below, hot zones are established in the bottom layer of coke and in the layer immediately supporting the coal by adm itting independent air blasts to each zone ; during this stage the blast gases are excluded from the coal, which is subsequently carbonised by a current of blue water-gas formed by the introduction of steam into the lower hot zone and strongly heated during its passage through the upper hot zone. L. A. Co l e s.

Destructive hydrogenation of carbonaceous m aterials. A. J. ^{v a n} Pe s k i (B.P. 315,780, 18.1.28).—

The materials are heated with hydrogen in the presence of catalysts such as calcium, iron-tungsten, or nickel carbides in an autoclave at 460° and 45 atm. (cf. B.P.

315,193 ; B., 1929, 770). C. B. Ma r s o n.

Gas producer. II. P . S m i th , Assr. to G a s R e s . Co.

( U .S .P . 1,724,525, 13.8.29. Appl., 30.1.22).—A gas

producer adapted to be assembled in the inverted position comprises a producer shell open at the lower end, a ring supported within the shell, and a lining extending beneath the ring and supported thereby when the shell is in the inverted position. The lining can be inserted into the shell through the lower end, for which a closure plate is provided.

' A. B. Ma n n i n g.

Gas retorts. H. K o p p e r s , Assr. to K o p p e r s D e v e l o p m e n t C o r p . (U.S.P. 1,725,148—9, 20.8.29.

Appl., 8.7.21. Renewed [b] 10.3.27. Ger., [a] 17.11.19, [b] 2.2.20).—(a) A gas retort setting consists of a number of inclined retort chambers surrounded by heating Hues, below which are regenerators. The latter are connected to intermediate chambers which in turn are connected by ducts to the heating flues. Movable nozzles which can be operated from outside the structure and which communicate with the ducts leading to the flues can slide along guides in these chambers to a point adjacent to the ends of the flues, (b) A setting of retorts is arranged in a common flame chamber which is partitioned into two groups of flues, for alternate inflow and outflow. The partition extending into the crown space of the chamber is provided with a port which determines the place of flow from the inflow to the outflow side. Regenerators are provided connected, respectively, to the inflow and outflow flues.

A. B. Ma n n i n g.

Desulphurisation of gas. R. M. Cr a w f o r d (U.S.P.

1,724,909, 20.8.29. Appl., 3.7.26. Renewed 23.1.29).—

The gas is washed with a solution containing an alkali carbonate derived from the decomposition of an alkali

phenoxide. A. R. Po w e l l.

Apparatus for hot purification [desulphurisation]

o f g a s e s . Co m p. In t e r n a t, p o u r l a Fa b r. b e s Es s e n c e s e t P é t r o l e s ( B .P . 298,236, 5.10,28. Fr., 6.10.27).—

Distillation, producer, and other gases are desulphurised by passing them over the purifying material which is mounted on a carrier of porous material and is situated in chambers of annular cross-section. The heat liberated during regeneration is thereby easily dissipated owing to the large radiating surfaces of the annular compart

ment, which may be of a width progressively increasing from the zone which, during regeneration, is a t the highest temperature. C. B . M a r s o n .

Treating coke-oven gases and like gases. U n i o n C h im . B e l g e S o c . A n o n . ( B .P . 316,174, 17.9.28. B e lg ., 24.7.28).—The gases are treated with an ammoniacal solution which not only contains ammonia recovered from the condensate, but is made alkaline by the absorption of anhydrous ammonia. The resulting solution is caused to react with a suspension of calcium sulphate as described in B .P . 262,320 (B., 1927, 107).

The anhydrous ammonia used for making the ammoniacal solution is utilised as a cooling agent for condensing benzol from the gas. A. B. M a n n i n g .

Recovery of gas tars from their em ulsions with water. R . R . R i p l e y and S . C. S c h w a r z ( U .S .P . 1,724,222, 13.8.29. Appl., 22.4.24).—A small propor

tion of a demulsifying agent is added to the emulsion and the mixture is rapidly heated to its b.p. under atmospheric pressure. The heating is continued, under correspondingly increased pressure, to a temperature below th at at which appreciable cracking occurs, and the mixture is maintained thereat until the water particles coalesce. The heating is then discontinued and the mixture allowed to separate by gravity.

A . B . Ma n n i n g.

Obtaining light hydrocarbon oils from tar sands. A. R u l e , H. G. W a t t s , and I m p e r i a l C h e m . I n d u s t r i e s , L t d . ( B .P . 317,346, 11.5.28).—Light hydro

carbons are produced by the destructive hydrogenation of carbonaceous material which has been extracted from tar sands. The light oil or the middle oil from a previous hydrogenation forms a suitable solvent for the extraction, which is preferably carried out a t tem

peratures above the normal. The middle oil produced may be separately treated, either by destructive hydro

genation or by cracking, to produce a further quantity of light oil. ’ A. B . M a n n i n g .

Heat treatm ent of oil shale or sim ilar m aterials.

R. V. Wheeler, A. P. and A. H . Pehrson (B.P. 316,652, 2.5.28).—To destroy or minimise th e adhesive or stick

ing properties of the materials when heated, they arc subjected to a low-temperature preheating treatm ent at 100—150°, and through them are passed heated gases (other than air) containing a t least 10% 0 2 (e.g., flue gases) for \ — 2 hrs. The shale is preferably subjected to a tumbling-over action during the treatment.

W. S. No r r i s.

Hydrogenating and cracking organisation [for m ineral oils]. ^{M .} J. T r u m b l e (U.S.P. 1,725,320, 20.8.29. Appl., 24.12.24, Renewed 12.11.28).—The apparatus comprises an equilibrium chamber having an outlet for lighter fractions, a superposed hydrogenating chamber, and means, independent of one another, for supplying, fresh material and for circulating the heavier fractions through the two chambers. L. A. C o l e s .

(7)

B r itis h C h e m ic a l A b s tr a c ts —B ,

Cl. II.—Po e l ; Ga s ; Ta u ; Mi n e r a l Oi l s.

Decom position of hydrocarbons into those con- - tam ing fewer carbon atom s. A. J. van Peski (B.P.

315,890, 18.1.28).—Decomposition of hydrocarbons, without the use of hydrogen, is efiected by passing them over catalysts consisting of one or more of the elements sulphur, antimony, arsenic, selenium, or tellurium, and/or of compounds of sulphur, antimony, or arsenic, with halogens or halogen compounds at ordinary, low, or high pressures and at ordinary or increased tempera

tures. C. B. M a r s o n .

Converting hydrocarbons of high b.p. into those of low b.p. 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. 315,991, 7.7.28).—Mineral oils, tars, and their hydrogenation products are converted into hydro

carbons of low b.p. by subjecting them, a t 410—600°

and in the presence of gases or vapours and of suitable catalysts, to the action of aldehydes or ketones which contain more than 3 atoms of carbon in the molecule.

C. B. M a r s o n .

Conversion of hydrocarbons of high b.p. into others of low b.p. 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. 316,637, 26.4.28).—Cracking of

heavy hydrocarbon oils is carried out in the presence of a catalyst consisting of or containing salts of meta- phosphoric acid, particularly those of the metals of group V I ; the catalygt may be carried on pumice, silica gel, etc. The process is preferably operated by passing the vaporised hydrocarbon, which may be mixed with nitrogen, carbon dioxide, or other inert gas, over the catalyst heated at 400—800°, under pressures up to 50 atm. In addition to liquid products of low b.p., gaseous unsaturated hydrocarbons are usually obtained. In an example, brown-coal tar, passed in vapour form at 600° over uranyl metaphosphate on pumice, yielded 35% of benzine (b.p. below 200°), 20%

of cracked gases containing 35% of defines, and a coke- free residue (b.p. above 200°). W. S. N o r r i s .

Conversion of heavy into light hydrocarbon oils. E . C. R. M a r k s . From D e u t s . E r d ö l A.-G.

(B.P. 316,600, 30.4.28).—In a plant for cracking heavy mineral oil, the heating of the heating zone is sub

divided into sections in such a way th at from the point where the oil reaches the lowest cracking temperature (about 390°) the heating per unit length of section is increased by comparison with the preceding section ; for this purpose a long and thin tube {e.g., 200 in. long, 60—80 nun. diam.), conveniently serpentine in form, is employed. At least two heating spaces are employed, and these may be associated. W. S. N o r r i s .

Recovery of products from [distillation of hydro

carbons in] fractionating condensers. L. W. S n e l l

(Ü.S.P. 1,725,219, 20.8.29. AppL, 23.8.26).—Predeter

mined vapour temperatures are maintained a t each end of one of the condensing zones of a fractionating condenser with the production of fractions of predeter

mined initial- and end-points, by discharging portions of two different fractions, after they have been cooled, into the vapours respectively entering and leaving the zone, the rates of flow of these portions varying in accordance with variations of the temperature of the vapours into which they are discharged. The remaining portions of the fractions are recovered separately.

L. A. C o l e s .

Sw eetening of hydrocarbon d istillates. T. B

K i m b a l l (B.P. 291,379, 25.5.28. U.S., 31.5.27).—

Sulphur compounds (mercaptans) are removed from normally liquid hydrocarbons by vaporising the hydro

carbons and bringing them into countercurrent contact with non-oxidising, aqueous, alkaline solutions (e.g., of alkali hydroxides) heated to a temperature above the condensation point of the hydrocarbon vapours but below the b.p. of the alkaline solution a t the pressure

employed. W . S. N o r r i s . .

Refining of lubricating oil in hydrocarbon m otors. ^{W .} B. C l i f f o r d , Assr. to C l i f f o r d C o r p .

(U.S.P. 1,725,392, 20.8.29. Appl., 16.5.24).—An oil distilling chamber situated in the casing of an internal- combustion engine and heated by the exhaust gases is provided with means, controlled by the temperature in the chamber, for withholding the supply of oil until the distilling temperature is reached and with an oil dis

charge adapted to maintain a constant oil level in the

chamber. L. A. C o l e s .

Apparatus for separating im purities from oils.

D e u t s . W e u f t A.-G. (B.P. 308,752, 21.6.29. Ger., 29.3.28).—The small water drops in the oil are con

glomerated-by allowing a current of the oil to impinge on a wall of rolled sheet iron, inclined to the direction of motion of the oil. A. B. M a n n i n g .

Stabilisation of clay-treated [lubricating] oils.

G . F . O l s e n , Assr. to G e n . P e t r o l e u m C o r p . o f C a l i f o r n i a (U.S.P. 1,724,510, 13.8.29. Appl., 31.8.26).—

After separation from the clay, and while still hot, the oil is atomised by a non-oxidising fluid in order to vaporise deleterious substances. F . G . C l a r k e .

Revivifying [oil-treated] adsorbent m aterials.

W . M . S t r a t f o r d , Assr. to T e x a s C^o. (U.S.P. 1,724,531, 13.8.29. Appl., 11.2.25).—Decolorising clay which has been used for refining hydrocarbon oils is extracted with a non-aqueous solvent, e.g., gasoline, a t a temperature above the normal b.p. of the solvent, and under a pressure sufficiently high to maintain the solvent in the liquid state. A. B. M a n n i n g .

Manufacture of soaps from sulphonated m ineral- oil acid sludge. O . E. C u s h m a n and T. W . D o f . l l ,

Assrs. to S t a n d a r d O i l Co. o f C a l i f o r n i a (U.S.P.

1,718,335, 25.6.29. Appl., 28.7.23).—A demulsifying agent is produced by treating a mineral oil with sul

phuric acid, separating the sludge from the oil, which is then treated with sulphuric acid of above 97% concen

tration, and the sludge again separated. The sul

phonated products of this second sludge are separated from the free sulphuric acid therein and neutralised, after which oil-soluble colouring m atter is extracted with

benzol. S . S . W o o l f .

Cold asphalt and application thereof. O. Y.

I m r a y . From I . G. F a r b e n i n d . A.-G. (B.P. 317,496, 16.3.2S).—Bituminous substances are dispersed in water by adding to the mixture finely-ground humic acid, brown coal, or other substances containing humic acid. The dispersions are prepared by simple stirring, and do not require the use of a colloid mill. Materials for road making, or for the construction of ceilings, walls, etc., are made by adding basalt chips, sand, cement, etc. to the dispersion. A. B. M a n n i n g .

b

(8)

844 Cl. I I I . — Or g a n i c In t e r m e d i a t e s.

Coal distillation apparatus. W. M. C a r r and T. J.

A s h l e y (A . E. A s h l e y , extrix.) (U.S.P. 1,726,058, 27.8.29. A p p l., 25.2.26. U.K.. 3.3.25).—See B.P.

248,557 ; B., 1926, 477.

D istillation and burning of coal. II. S. R e e d and

R . D. L a m i e (B.P. 318,373, 17.8.28).—See U.S.P.

1,696,731; B., 1929, 704.

Manufacture of carbon. A. L e d e r e r (U.S.P.

1,725.359, 20.8.29. Appl., 7.10.26. Austr., 24.4.25).—

See B.P. 251,244 ; B„ 1927, 244.

Removal of carbon deposits from engine cylin

ders. C. A. I I o c h w a l t , Assr. t o G e n . M o t o r s R e s . C o r p . (U.S.P. 1,726,437, 27.8.29. Appl., 18.9.23).—See B.P. 222,077 ; B., 1924, 1005.

Manufacture of porous m a ss [for storage of acetylene]. E. S t e i l , Assr. to A m e r . G a s a c c u m u l a t o r C o. (U.S.P. 1.726,323, 27.8.29. Appl., 22.10.25. G e r „

I.11.24).—See G.P. 420,150 ; B., 1926, 230.

Production of gases rich in ethylene. H. S u i d a ,

Assr. to I. G. F a r b e n i n d . A.-G. (U.S.P. 1,726,04S, 27.8.29.

Appl., 24,6.24. Austr., 26.6.23).—See B.P. 237,415;

B., 1925, 748.

Containers for dry-cooling of hot coke. S u l z e r F r e r e s S o c . A n o n . (B.P. 306,933, 1.1.29. S w itz .,

29.2.28).

Safety device for burners. S p e n c e r T h e r m o s t a t

Co., Assees. of N. T . S e l l m a n (B.P. 300.507, 12.11.28.

U.S., 12.11.27).

Coal-dust, gas, and oil burner for constant velocities of ejection under variable loads. W i t - k o w i t z e r B e r g b a u - u . E i s e n h u t t e n - G e w e r k s c h a f t ,

and C. S a l a t ( B . P , 298,080, 1.10.2S. Ger., 1.10.27).

Gas reactions (B.P. 317,996).—See I. Unsaturated hydrocarbons (B.P. 298,090 and 315,895).—See III.

Protecting cables etc. (B.P. 293,835).—See X. Solid grease (B.P. 317,630).—See XII.

n i.— ORGANIC INTERMEDIATES.

M icrochem ical detection of acetic acid as sodium uranyl acetate. D. K r u g e r and E. T s c h i r c h

(Pharm. Ztg., 1929, 74, 1096—1097).—0-5 mg. of free acid may be readily detected by bringing a crystal of sodium formate and a crystal of uranyl formate into contact with opposite edges of the drop on the object glass. Acetate solutions are evaporated to dryness on the object glass, and the residue is treated with a drop of sodium uranyl formate solution. Benzoic acid inter

feres even in small quantities, and should be removed before the t e s t ; other common acids interfere onlv when present in large quantities. S . I. L e v y .

U se of aldehydes and dihydroxyacetone in the detection and differentiation of phenols. I.

Colour reactions given in sulphuric acid solution.

I I . Precipitation and staining tests involving the use of hydrochloric acid. III. Detection of cresol in carbolic acid by m eans of van illin . A . H . W a r e

(Quart. J. Pharm., 1929, 2, 249—253, 254—264, 265—

266).—I. The methods adopted in the use of dihydroxy

acetone, tartaric acid (giving glycollaldehvde), and form

aldehyde are described, and their colour reactions with 22 phenolic substances tabulated.

II. Details of the procedure adopted whereby formaldehyde in particular (tabulated results) and dihydroxyacetone may be employed to effect the separa

tion of phenols in the presence of hydrochloric acid are given. A new staining test for distinguishing phenols in which a filter paper is used as the material to be stained and drops of the reagents are allowed to fall thereon and subsequently dried, is described, and the colour reactions are tabulated together with those of the deal shaving test for seven phenols.

III. By means of a 2% solution of vanillin in alcohol a minimum of 1 • 5% of o- and m-cresol can be detected in carbolic acid. C. C. N. V a s s .

T ests for phenols involving the u se of hydrogen peroxide. A. H. W a r e (Quart. J. Pharm ., 1929, 2, 267—270).—The colour reactions of certain phenols in sulphuric acid solution when acted on by hydrogen peroxide alone or in conjunction with dihydroxyacetone or formaldehyde are described. Apparently specific, or relatively specific, results are indicated for the catechins, pyrocatechol, phloroglucinol, resorcinol, thymol, and

gallic acid. C. C. N. V a s s .

Action of catalysts on carbon m onoxide-hydro- gen. A u d i b e r t and R a i n e a u . —See II.

Pa t e n t s.

Production of liquid p olym erisation products from gases containing hydrocarbons. C. E p n e r

(B.P. 317,344, 9.5.28).—Methane, or gases containing methane, are subjected to the action of an alternating, high-tension electric field producing a silent electric discharge and having a frequency of 8—12 X103 cycles/

sec. The reaction is carried out in the presence of catalysts which promote condensation or hydro

genation, and at temperatures, e.g., 150—500°, a t which the products are in the form of vapour or a mobile

liquid. A. B. M a n n i n g .

Manufacture of unsaturated hydrocarbons.

Soc. C h e m . I n d . i n B a s l e ( B .P . 298,090, 1.10.28.

Switz., 1.10.27).—Unsaturated aliphatic hydrocarbons are made by reaction between methyl alcohol and an alkaline-earth carbide at 200—300° and under ordinary pressure ; the uncondensed gases such as acetylene are either collected, allowed to escape, or returned by a circulating pump to the heated reaction vessel so th at they may undergo further reaction to produce hydro

carbons of higher b.p. which are removed by condensa

tion. The carbide is automatically introduced into the reaction vessel, and means are provided for con

tinuously freeing the carbide from the oxide which is formed during the reaction. C . B . M a r s o n .

M anufacture of unsaturated hydrocarbons. 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.

315,S95, 16.3.28).—Pure, unsaturated, gaseous hydro

carbons such as ethylene, propylene, butylene, and amylene are manufactured by cracking mineral oils and tars at 600—800° in the presence of gases or vapours, such as water vapour, and, if desired, with the aid of catalysts (e.g., silicates with difficultly reducible oxides deposited thereon ; also certain metals or alloys). The