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BRITISH CHEMICAL ABSTRACTS

B — APPLIED CHEMISTRY

A PRIL 24 and MAY 1, 1931 *

I-GENERAL; PLANT; MACHINERY.

H igh-speed d isp ersin g m achin es [colloid m ills].

W. Gr o h n (Chem. Fabr., 1931, 1—4, 13—15, 27—28).—

The pioneer work of Plauson is described. Colloid mills fall into two classes : (1) beater mills, such as the original Plauson m ill; (2) mills in which the dispersion is forced through a slit as a thin film by high-speed rotors. Several mills of the first class, including some operating by centrifugal force, are described. Those of the second class (Premier mill and others) are especially suited for the preparation of emulsions. The improve­

ments made in the Plauson mill are chiefly concerned with the increase of speed and reduction of power requirements. The eccentric position of the beaters was retained, although it involved a circulating of the liquid within the mill, which absorbed power. In the Oderberger colloid mill, however, the liquid is imme­

diately removed by a pump, the action of the beaters being merely dispersive. The various theories of the action of the beater mill, as proposed by Plauson, Block, and others, are reviewed and criticised. Travis’

view, th a t colloid mills only deflocculate secondary aggregates without breaking up large prim ary particles, is not accepted. The “ vacuum dryer colloid m ill”

effects improved results by forcing the liquid in counter- current to the direction of movement of the beaters, and by the use of subsidiary additional beaters. Probably dispersion is a function of relative velocity of beaters and liquid, and of the number of impacts. C. Ir w i n.

V iscous flow and surface film s. R . Bu l k l ey

(Bur. Stand. J. Res., 1931, 6, 89—112).—From a repeti­

tion of the experiments' of Wilson and Barnard on the flow of oils containing fa tty acids through capillary tubes (B ., 1922, 929), it appears probably th a t the clogging up of the capillaries observed by these authors was duo to the presence of foreign particles in the oil, for when the liquids are efficiently filtered clogging does not occur. The flow of various liquids in platinum and glass capillaries with internal radii as small as 9'35 and 5-59 ¡a, respectively, has also been investigated. The radius of a given capillary, as calculated from the rate of flow by Poiseuille’s equation, is found to be the same for all the liquids flowing through, and in the case of the smallest glass capillaries the calculated radii correspond with the radii measured directly. Further, for a constant pressure difference between the ends of the capillary, the rate of flow does not vary with the time, but is proportional to the pressure in all cases. I t is therefore concluded th a t if there is any motionless adsorbed film on the walls of the capillary its thickness

cannot exceed 0-02—0-03 ¡x, and th a t the liquid has its bulk viscosity to within this distance from the wall.

R. Cu t h il i..

T heory of rectification in packed colum ns. E.

K irschbaum (Chem. Fabr., 1931, 38—40, 51—53, 63—

65).—A mixture of two liquids of different b.p. under­

going distillation is considered. If xv is the percentage number of mois, of the more volatile component present in the vapour and xi th a t in the liquid a t any point in the column, then x v — ra(u-j-l)-fa/0(t’+ l ) , where xD is the content in the product and v the ratio of con­

densate to distillate, if fractionation is complete. This line is plotted, and the effect of packing considered graphically. The case of partial condensation is simi­

larly treated. A packed column is considered as pro­

viding continuous contact between liquid and vapour having tem perature differences corresponding to the differences between the b.-p. curve and condensation curve. If S is this difference, a the heat transmission between liquid and vapour, R the latent heat of evapora­

tion, and F the heat-exchange surface, then the rate of condensation dC = dFoiS/R. The value F depends on the dimensions of the packing and the height of the column, and may be replaced by KdH.

From this an integral equation is obtained, which gives a relation between the height of the column and yield of distillate, and is capable of graphical solution. The quantity a is dependent on the form of packing, vapour velocity, and reflux ratio, and requires determination for each case. I t also, of course, varies with the vapour concentration. The case of a benzene-toluene mixture is taken as an example, and the necessary curves are worked out both for a simple column and dephlegmator, and for continuous still with distillation and rectification

columns. C. Ir w i n.

B ehaviour of m ou ld s on expansion [in sulatin g]

corks. J . Gr e g e r (Z. Unters. Lebensm., 1930, 60, 532—536).—Crude cork {e.g., outer bark and stopper- manufacturers’ refuse) used as an insulator may be infected by bacteria and moulds (Pénicillium, Mucor, Aspergillus, Dematium) which can develop subsequently under favourable conditions owing to the presence in the cork of the necessary nutrient substances (primary infection). The action of hot air for 2 hrs. a t 100° or 30 min. a t 150° destroys the spores, but secondary infection may occur subsequently if tem peratures below 250° are used. H ot air a t 260° for 10 min. results in complete sterilisation, owing to the destruction of the

nutrient substances. J. Gr a n t.

B oiler w ater.—See X X III.

* The rem ainder of th is set of A bstracts will appear in n ex t week’s issue.

369 a

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B r i t is h C h e m ic a l A b s t r a c t s — B .

370 C l. I.—Ge n e r a l ; Pl a n t ; Ma c h i n e r y.

Pa t e n t s.

Apparatus for preparing [roasting] granular or lik e m aterials. J. L. Ro s e n f ie l d (U.S.P, 1,773,202,

19.8.30. Appl., 21.2.27).—Material, such as coffee, peanuts, etc. is roasted while in contact with a heat- carrving agent such as sand. The sand is preheated, and the drum which conveys the material is also heated throughout its length. B. M. Ve n a b l e s.

T unnel drying ovens. Ak t ie b o l a g e t Sv e n s k a

Fl a k t f a b r ik e n (B.P. 342,225, 7.5.30. Swed., 7.5.29).—

The drying air is circulated transversely to the goods by means of a number of fans, b u t its general motion is longitudinally countercurrent to the goods. When approaching the inlet (for the goods) the air passes over heaters during the transverse circulation, so th a t it arrives at the inlet end in its hottest and moistest Con­

dition ; thence it is led back about half way, and passes over heat exchangers (in the place of the positive heaters) moving concurrent to, but out of contact with, the goods and giving up considerable heat of condensa­

tion to fresh air circulating transversely in the cooler and drier end of the kiln. External heat exchangers and fans are also placed a t one or more alternative points.

B. M. Ve n a b l e s. Introducing gaseou s, vaporous, or liquid agen ts into a m eltin g bath of h igh tem perature. F . Kr u p p

A.-6 . Fr ie d r ic h-Al f k e d- Hu t t b (B.P. 341,873, 21.10.29.

Ger., 11.6.29).—Gaseous or liquid addition agents are supplied continuously through a pipe which is periodi­

cally raised out of the molten bath before its critical period is reached. A protective layer of the molten mass is produced by cooling, and this is aided if the pipe is wrapped with asbestos cord. G. A . Ki n g.

Vertical w ater-tube boiler for w aste heat, esp ecially of w ater-gas. Da jip f k e s s e l f a b r. v o r m. A. Ro d b e r g A.-G. (B.P. 342,201, 22.3.30. Ger., 23.3.29).—A nest of vertical tubes substantially , fills the space within a vertical cylindrical stack, the tube ends being connected to steam and water drums arranged horizontally a t the top and bottom. B. M. Ve n a b l e s.

Apparatus for recovery of ch em icals and heat from w aste liquors. C, L. Wa g n e r, Assr. to C.L.W.

Pa t e n t s Co r p. (U.S.P. 1,771,829, 29.7.30. Appl., 24.1.25).—A vertical retort with an outer airtight casing and an inner refractory lining is divided into upper and lower communicating zones, each having adjustable inlets for air. After heating the retort to the requisite temperature by burning downwardly-directed jets of atomised oil, the oil supply is replaced by the waste liquor (e.g., paper pulp waste products), which is then atomised and burned partly in the upper and partly in the lower zone, whilst the waste gas, the heat of which is utilised in a suitable manner, and the non-gaseous residue (e.g., sodium carbonate) are withdrawn through outlets in each zone. F. R. En n o s.

Steam -heated heat exchangers. S c h m i d t’s c h e H e is s d a m p f - G e s .m .b .H . (B.P. 341,767, 7.3.30. Ger., 25.4.2-9).—A rc-superheater or other type of apparatus comprising a number of U -tubes arranged lengthways iu a drum has the outlet or lower header rigidly connected to the drum. The steam is led to the upper header by a

pipe of some length and having bends to introduce flexibility. B . M . Ve n a b l e s.

Centrifugal dryer. L. B. Gr e e n, Assr. to Bo r d e n

Co. (U.S.P. 1,772,863, 12.8.30. Appl., 25.3.27).—

A detachable perforated basket is placed within an imperforate, slightly conical one, the latter being pro­

vided with heavy truly balanced weights and attached to the driving shaft by means of a hollow conical boss jammed on to a lump of rubber or other resilient material on the upper end of the shaft. B. M . Ve n a b l e s.

D rying apparatus. L . N . Ll o y d, and Ph i l l i p s

En g. Co., Lt d. (B.P. 341,407, 3.8.29).—A form of air­

lock, suitable for charging a drying chamber operating under vacuum or pressure, is described. (Cf. B.P.

336,602 ; B., 1931, 2.) B. M . Ve n a b l e s. D rying apparatus. 0. Pf e i f f e r (B.P. 341,587, 31.10.29).—H ot gases are deflected upwards from a flue into the drying apparatus and down again into the flue by suitable flap doors. The dryer comprises deep narrow pockets alternately for goods and flue gases.

B . M. Ve n a b l e s. Steam dryer, or grit and dust extractor from air or g ases and the like. F. K . 0 . Mo y na n (B.P.

341.532.18.10.29).—A stationary apparatus of the whirl­

ing type is described. B . M . Ve n a b l e s, D ryers and the like [for sh eet m a te r ia l; e.g., w all-board]. Coe Ma n u f g. Co., Assees. of R. C.

Mo o r e (B.P. 340,510, 20.8.29. U.S., 16.2.29).—A dryer of the type described in B.P. 314,013 etc. (B., 1931, 139) is provided with extensions forming sealing chambers a t the inlet and outlet ends, the atmosphere within which is m aintained by fans exactly equal in quality and pressure to th a t within the dryer a t the respective ends. B. M . Ve n a b l e s.

D rying of h ides, sk in s, leather, plyw ood, etc.

J. J. Bu r t o n (B .P . 341,932, 19.8.29).—Heated and con­

ditioned air is adm itted to a drying chamber, from a longitudinal duct underneath, through pipes which, are kept swinging transversely. The air is exhausted from the apex of the roof by means of a fan. A suitable heater for the air is described. B . M . Ve n a b l e s.

Crusher. G. E . Ch a m b e r l a in (U.S.P. 1,773,476, 19.8.30. Appl., 7.3.25).—The apparatus comprises two chain belts running towards each other down the sides of

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

H am m er crusher. W. A. Ba t t e y, Assr. to Pe n n­

s y l v a n ia Cr u s h e rCo. (U.S.P. 1,772,533,12.8.30. Appl., 25.8.28).—The upper p art of the grid of a crusher of the disintegrator type is formed of spaced bars through which the hammers intercaleate ; the bars also form the bottom of the feed hopper and pivot on a strong pin a t one end, and are secured by weak shear pins a t the end to which the rotor runs upwards, so th a t they will yield to un- crushable matter. B. M . Ve n a b l e s.

H am m er m ills. C. Nie l s e n (B.P. 341,824,15.5.30).

—Swing hammers for disintegrators are formed as hollow castings hollowed out more a t the pivot end so as to reduce scrap material. The pivots are placed in eccentric bushings to restore the radius of worn hammers.

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

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

C l. I.— Ge n e r a l ; Pl a n t ; Ma c h i n e r y. 371

Ball m ill. A. A. Wis e and G. Ga t e s (U.S.P.

1,772,737, 12.8.30. Appl., 28.5.28).—The cylindrical shell has one closed end to which is attached the driving shaft running in a spherical bearing. The mill has one tyre, and the distance between the supporting rollers is variable, to alter the inclination of the mill to the horizontal. B. M. Ve n a b l e s.

G rinding and separating m ill. E. Ju n g e l s,

Assr. tO SCHNELLPRESSENFABR. A .- G . HEIDELBERG (U.S.P.

I,773,228,'19.8.30. Appl., 5.11.28. Ger., 8.11.27).—

A disintegrator is provided with means to create a strong air current, and below it is a collecting chamber for coarse material. The air-borne fine material passes sideways through a screen to a bag filter or other collect­

ing device, whence the air is returned to the mill.

B . M. Ve n a b l e s. Apparatus for disintegrating ore and other m aterial. Ha r d in g e Co., In c., Assees. of H . Ha r­

d in g e (B.P. 342,130, 27.1.30. U.S., 30.1.29).—A mill of the Hardinge type, instead of being cylindro-conical, is formed of three conical portions. The feed end is as previously constructed ; next, abutting base to base, is the main portion, of length greater than the maximum diameter, which has a comparatively slow taper ; and lastly, there is the outlet cone of about the same angle as, bu t of lesser diameter than, the inlet end. The angles indicated in the figure are 60°, 7 |° , and 60°, respectively, with respect to the axis.

B . M. Ve n a b l e s. Production of granular substances. 0 . H . B u s e , Assr. to G r a s s e l l i Ch em. Co. (U.S.P. 1,773,257,19.8.30.

Appl., 13.2.28).—The substance while in a liquid con­

dition is sprayed upwards into a relatively stagnant body of air which is surrounded by rapidly moving air currents. The process is particularly suitable for the granulation of sodium bisulphate. B . M. V e n a b l e s .

M ixing of granular or like m aterials. F. Kr u p p

Gr u s o n w e r k A.-G. (B.P. 341,821, 10.5.30. Ger., II.5.29).—A rotating drum contains a receiving chamber and a discharge chamber in line around the shaft, the former being of large capacity and effecting preliminary mixing so th a t in continuous work comparatively large portions of each constituent may be added ; outside these chambers are annular passages having internal blades inclined alternately from the opposite walls.

Only one entrance port is provided from the preliminary chamber into the bladed chambers so that, with slow rotation of the drum, the final mixing is effected in small

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

M ixing of powdered m aterial. P . Go e b e l s, Assr. to G. Po l y s iu s A.-G. (U.S.P. 1,773,619, 19.8.30.

Appl., 3.1.29. Ger., 9.12.27).—The constituents are stored in separate pressure-tight containers; a conveying pipe is connected through individual valves to the lower end of each container and runs round to the top of every container, again with a valve to each ; there is also a valved outlet to an external place situated where the conveyor pipe turns upwards. The contents of a group of containers, after loosening, are blown by compressed air into another group, and the mixture thus formed is blown to the external place by means of the residual

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

Filtering liqu ids. N . E. Nil s s o n (B.P. 341,645, 3.12.29. Swed., 4.12.28).—The water or other liquid is passed through a preliminary strainer which hangs more or less vertically over a collecting chamber for coarse material and is kept clean by means of scraping laths. The strained water then passes horizontally through a finer filter which is hinged a t the top end and a t the lower end is given a motion, by means of a cam and spring, which is slow in the direction counter- current to the water and rapid in the opposite direction, overtaking the water ; any collected m atter is thereby dislodged and falls into the collecting pit.

B. M. Ve n a b l e s. [Spray separator for] evaporators. S. v o n le

Ju g e (B.P. 341,751, 17.2.30).—The dome for separation of entrained liquid from vapour is entirely external to the evaporator and is provided with a separator, com­

prising filling material sandwiched between two per­

forated plates, which is capable of being flushed with live steam, the washings being led to waste or back to the evaporator feed. B. M. Ve n a b l e s.

Apparatus for treating liqu ids. A. Je n s e n (U .S .P . 1,772,898, 12.8.30. Appl., 20.4.26).—A heater or cooler of the rotating-coil type is described.

B. M. Ve n a b l e s. Countercurrent contacting apparatus. 0. L*

Ca m p b e l l, Assr. to E. B . Ba d g e r & Sons Co. (U.S.P.

1,773,258, 19.8.30. Appl., 2.2.27).—In a bubble tower the trays are provided with baffles (for the liquid) across the greater p art of a diameter and the downflows to and from any plate are a t opposite sides of the closed end of the baffle, so th a t the liquid has to take a U-shape or rotary course. Successive trays are assembled a t a slight angle to each other so th a t the direction of rotation of the liquid is the same on every tray.

B. M. Ve n a b l e s. C atalytic converter. D. F. Sir d e v a n, Assr. to Ge n. Ch e m. Co. (U .S .P . 1,773,322, 19.8.30. Appl., 12.3.26).—The apparatus comprises a vessel provided with spaced, perforated, and firmly secured diaphragms upon which is placed a medium, such as asbestos, th a t must not become compacted. B. M. Ve n a b l e s.

A dsorption of ga ses. L ’Ai r Liq u id e Soc. An o n,

p o u r l’Et u d e e t l’Ex p l o it, d e s Pr o c. G. Cl a u d e, Assees. of Soc. Ch i m. d e l a Gr a n d e Pa r o is s e, Azote &

Pr o d. Ch im. (B.P. 342,242, 16.6.30. Fr., 17.6.29).—

In a process involving the adsorption by solids of the less volatile constituents of a gaseous mixture, the gases are placed in contact with the adsorbent while still under pressure, but after cooling by heat exchange with the expanded remaining gas. B. M. Ve n a b l e s.

Absorption apparatus. A. Go d e l, Assr. to Soc. d e

Re c h e r c h e s & d’Ex p l o it. Pé t r o l if è r e s (U .S .P . 1,773,224, 19.8.30. Appl., 19.8.27. Fr., 21.3.27).—

The absorbent material is contained in an annular space within a cylindrical container, the axial space being occupied by a bundle of tubes with a jacket. The entering gases pass in one direction through the tubes and return through the absorbent, a fan being provided to draw the gas through and, if desired, to recirculate a portion. In the jacket is a heating or cooling medium for exact regulation of tem perature. B. M. Ve n a b l e s.

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B r i t is h C h e m ic a l A b s t r a c t s — B .

372 Gl. I I . — Fu e l ; Ga s ; Ta r ; Mi n e r a l Oi l s.

Apparatus for liqu efyin g air. M. Ha z a r d- Fl a-

m a n d (B.P. 341,537, 18.10.29. Fr., 19.10.28).—A

system of rectification involving two sections of rectifier and one or two additional compressors is used in con­

junction with the liquefaction apparatus described in B.P. 336,798 (B., 1931, 3). * B. M . Ve n a b l e s.

H ot-joint com pound. J. C. Wa s so n, Assr. to Pe n n s y l v a n ia Lu b r ic a t in g Co. (U .S .P . 1,770,187, 8.7.30. Appl., 1.2.27).—The composition contains an oil-soluble sodium sulphonate derived from a hydro­

carbon o i l; materials such as graphite, mineral fillers (zinc dust, red lead, etc.), and sulphite-cellulose waste liquor, paraffin oil, water, etc. may be added as desired.

L . A. Co l e s. Checker-work for heat exchangers in furnaces.

F. H. Lo f t u s and T. N. Ku r t z (B.P. 343,969, 27.9.29.

U.S., 31.1.29).

Refrigerant evaporator for cooling brine. J. C.

and C. R. Ho v e m a nand H. L. F. Mo u z e t (B.P. 343,643, 12.12.29. Fr., 13.12.28).

Vibrating siftin g screen s. F. Pir l o t and H.

El t g e s (B.P. 343,616, 29.11.29. Belg., 3.8.29).

D rum [w ithout corners], m ore particularly of stain less steel and intended for liquids easily acquiring bad taste. F. Kr u p p A.-G. (B.P. 344,307, 30.5.30. Ger., 7.6.29).

Rectification of the m ixed vapours issu in g from the generator of an absorption refrigerating m achine. B. Le h m a n n (B.P. 343,931, 25.11.29. Ger.,

28.11.28).

R otary k iln s.—See IX. Continuous extraction.

—See X II. B oiler w ater.—See X X III.

II.—FUEL; GAS; TAR; MINERAL OILS.

Continuous verticals. W. A. Cu r r ie (Gas J., 1931, 1 9 3 , 280—281).—The influence of tem perature on the carbonisation process and the relation of through­

put to rate of carbonisation are discussed. The rate of carbonisation is largely determined by the swelling power and size of the coal, and segregation of the coal of different sizes may occur during discharge of the bunkers. The swelling powers of coals may be rapidly compared by heating J g. of the coal (through 60-mesli) in a vertical silica tube (10 cm. long X 8 mm. bore, and provided with an asbestos plug to support the coal) to 900°, above the coal being placed a carbon rod 6 mm.

in diam. and weighing 2 g. The volume of the coal is observed, the coal heated for 5 min. a t 900°, cooled, the resultant coke extracted, and the change in volume expressed as a percentage of the coal volume. The figure obtained represents the swelling power of the coal.

Various methods of estimating the throughput of a retort are briefly discussed and an approximate equation enabling it to be calculated is given. H. E. Bl a y d e n.

H um ic acid from lign ite. H. St a c h (Z. angew.

Chem., 1931, 4 4 , 118—120).—Freshly prepared, moist humic acid, carefully freed from electrolytes by dialysis, is completely methylated by a small excess of diazo- methane in aqueous alcohol, in contrast to the dried product, which needs repealed treatm ent. Its carboxyl content may be determined by esterification with methyl-

alcoholic hydrochloric acid, or alkaline hydrolysis of the fully methylated product, the results obtained being concordant with each other and with the value for éthéri­

fication obtained with methyl iodide and alkali. Slightly lower values are obtained by complete méthylation of the debituminised lignite, from which the humic acid is prepared, by diazomethane in ether, or by esterifi­

cation with methyl-alcoholic hydrochloric acid. Slightly lower values still are obtained by complete méthylation or esterification of the residue left by extraction of the humic acids from the debituminised lignite by cold aqueous potassium hydroxide. A number of lignites from different localities are shown to be capable of méthylation by diazomethane to a degree bu t little inferior to th a t attainable with humic acid ; somewhat lower values were given by two samples of bituminous lignite with a superficial resemblance to coal, but a Westphalian coal was almost unacted upon. I t is sug­

gested th a t the behaviour on méthylation may serve as a test to distinguish between lignite and coal. This reactivity towards diazomethane is difficult to reconcile with lactonic or anhydride structures, and it is suggested th a t the ageing process th a t leads to the change of humic acid into lignite is of the nature of an irreversible de­

hydration of the humic acid gel. H. A. Pig g o t t. D evelopm ent of Dakota lign ite. V. E xtraction and study of the benzene-soluble portion. E. E.

Ha r r is, C. F. Be l c h e r, and A. W. Ga u g e r (Ind. Eng.

Chem., 1931, 2 3 , 199—204; cf. B., 1931, 323).—

Previous work on the solvent extraction of coal is briefly reviewed. Lignite from the Velva district (N.

Dakota) was extracted with benzene under pressure by the methods of Bone and of Fischer. Extraction up to a t least 4-3% of the dry ashless coal substance was effected. The composition of the extract, particularly when obtained under pressures up to 17 atm ., is analogous to th a t of m ontan wax obtained from German brown coal. When treated with aqueous caustic potash as in Bone’s method, the soluble portions were found to consist of aliphatic acids and not of phenols ; the whole extract was resolvable into waxy alcohols and acids, resins, and comjtounds of unknown composition.

I t is concluded th a t the Velva lignite differs from the Estevan lignite examined by Bone (provided th a t no decomposition of the lignite occurred with the Estevan lignite) in th a t the acid portion of the benzene extract consists of aliphatic acids instead of phenols.

H. E. Bl a y d e n. D ensity and proxim ate com position of som e Indian durains. L. L. Fe r m o r (Rec. Geol. Survey India, 1930, 6 3 , iii, 358—377).—Caking and non-caking durain from various coalfields of Gondwana age con­

tained, respectively: moisture 0-67, 3-76; volatile m atter 20-18, 23-45; fixed carbon 44-63, 38-00;

ash 34-52, 34-79%, and had d 1*628, 1-656, fuel ratio 2-21, 1-62. Average values for the ash-free caking durain and vitrain were, respectively : moisture 1-03,1-50; volatile m atter 31-05, 32-64 ; fixed carbon 67-92, 65-86 ; fuel ratio 2-19, 2-01% ; d 1 -286, 1 -267.

Those for non-caking durain and vitrain were : 5-6S, 9-46; 36-55, 34-07 ; 57-77, 56-47; 1-58, 1-68;

1-309, 1-298. Support is afforded for the theory th a t

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

Cr.. II.— Fu e l; Ga s ; Ta b ; Mi n e r a l Oi l s. 373

vitrain acts as a dispersion medium witli ash as the disperse phase. Ch e m ic a l Ab s t r a c t s.

Spontaneous ignition of H ungarian brown coal.

K. Gä r t n e r (Mat. Nat. Anz. Ungar. Akad. Wiss., 1929, 46, 378—406 j Chem. Zentr., 1930, ii, 3486).—

The ignition depends on the particle size and on the content of unsaturated carbon compounds, and not on the water and sulphur contents. The humus content is not related to the rise of temperature.

A. A. El d r id g e. Variation of release b y g ases b y preheating coals of[different rank. M. Le g k a y e (Chim. et Ind., 1931, 25, 18—21).—The contents of volatile m atter of Liege coals containing approximately the same proportions of vitrain and clarain, and with 7-3—27-6% of volatile matter, were, determined with and without an initial heating during which the temperature was raised to 400° within a period of 20 min. Eour samples of vitrain (10-2—29-0% of volatile m atter) obtained from a lump coal were examined in the same way. Preheat­

ing resulted in an increased yield of volatile m atter with coals containing less than 15% of volatile m atter and a decreased yield with coals containing more than 18%.

The vitrain containing less than 20% of volatile m atter gave an increased yield of volatile m atter after pre­

heating. The influence of oxygen during the preheating and the explanation of the results arc briefly discussed with reference to the rank of the coal.

H. E. Bl a y d e n. Sw elling of coal during coking. K. Baum and P. H e u s e r (Glückauf, 1930, 6 6, 1497, 1538 ; Fuel, 1931, 10, 5164).—To avoid distortion of the coke-oven walls and difficulties in discharging the oven, the swell­

ing pressure developed by the coal during coking should not exceed a certain limit, and should be followed by some shrinkage. A useful laboratory method of study­

ing these qualities was proposed by Korten (B ., 1920, 713a), and has been developed by Damm (B., 1929, 382), Hofmeister (B ., 1930, 495), and Koppers. In Koppers’ apparatus, which is simpler to operate than the others, the swelling takes place under a constant pres­

sure of 1 kg./cm.2, whilst Damm and Hofmeister keep the volume of the coal constant by suitably varying the load. A number of tests have been made by Koppers’

method, and a new apparatus has been designed based on th a t used by Damm and Hofmeister. W ith closer packing of the coal, i.e., with a higher bulk density, the swelling pressure increases. I t is not influenced, however, by varying the water content of the coking coal while keeping the bulk density, calculated on the dry coal, constant. Examination of the single-sieve fractions of a coking coal in Koppers’ apparatus shows a rise of the swelling curve with increasing grain size ; with all grain sizes above 2 mm. the coking qualities appear to be nearly uniform. Fusain shows no swelling tendencies. The expansion curves of the dull coal show very varied values ; no real expansion pressure was observed. Clarain develops a dangerous expan­

sion pressure only with a high bulk density. The vitrain proved in all cases to be the source of the expansion pressure. The extent of shrinkage is very different with the various bright coals. An attem pt is being made to

correlate the results obtained with Koppers’ apparatus and with the modified Damm-Hofmeister apparatus.

A. B. Ma n n in g. Com plete gasification of sm a ll coke. L . M . Wil s o n (Fuel, 1931, 10, 69—71).—When working a rotary gas machiue on unscreened coke (2£ in. to 0 in.) trouble was experienced due to clinker formation near the walls. The feed arrangement was then modified by providing a shoot having one side lower than the other, and a vertical plate hinged just above the centre line of the bells and capable of being swung across the exit of the shoot, so th a t the fines, leaving the lower side of the shoot, could be concentrated against the walls of the machine. The walls were also water-cooled and corrugated on the inner surface. W ith this arrangement the coke was successfully gasified. A . B. Ma n n in g.

Form ation of fractures in coke. R. G. Da v ie s

and R. V. Wh e e l e r (Gas World, 1931, 94, Coking Sect.,

2 02 1).—A miniature oven built for the study of the formation of fractures in coke is described. The coal used is crushed to pass ^-in. mesh and conditions in the oven approximate to those of rapid-coking practice.

Photographs of the coke next to the oven walls obtained after coking for 2 f , 3{, and 5 J hrs. confirm Thau’s observations ; the cracks appear immediately after the beginning of the coking process and follow the move­

ment of the plastic layer, their lengths increasing proportionately. H. E. Bl a y d e n.

D eterm ination of thiocyanates in coke-oven liquors. A . Tr a v e r s and Av e n e t (Compt. rend., 1931, 192, 52—53).—Sulphides are precipitated with cadmium or zinc, and in the presence of several g. of thiosulphates (resulting from oxidation of polysulphides) per litre, the thiocyanates are precipitated in the cold by a 1 0% excess of copper sulphate, in a medium satur­

ated with sulphur dioxide to ensure dissolution of the double thiosulphates of sodium and copper. After 3 hrs. the precipitate is filtered off, washed, dissolved in an excess of ammonia, and the copper oxidised by boiling with hydrogen peroxide. The cold mixture is titrated in the presence of a 15% excess of sulphuric acid with potassium permanganate solution, whereby the CNS' ion is converted into cyanide, which does not react further, and the sulphur is oxidised (6KMn04 EE 5CNS). The error is 1%. J. Gr a n t.

T he carbon-black flam e. W . B. We ig a n d (Ind.

Eng. Chem., 1931, 23, 178—181).—The basic difference between carbon black and lampblack is defined in terms of the method of collection, and possible causes of the unique properties of impingement blacks are discussed.

By reference to two types of carbon-black flames (round and fiat), the conception of “ combustion quotient,”

s/v, where s is the to tal combustion surface and v the volume of gas contained within s, is developed and ap­

plied to variations in flame size and shape, and draught.

The position of the impingement surface, the effect of flame, shape of gas flow, and position of channel are factors of importance in large-scale operations th a t are discussed in relation to the quality and quantity of black obtained. H. S. Ga b l ic k.

The tar ind ex in the presence of copper (K upfer- verteeru n g szah l). K. Ty p k e (Petroleum, 1931, 27 ;

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B r itis h C h em ica l A b s tr a c ts — B .

S ’74 C l . II .— F u e l ; G a s ; Tar; M i n e r a l O i l s .

Motorenbetr., 4, 3—7).—Investigation of tlie factors influencing the tar index (Kissling’s method) shows th a t the results are slightly affected by the time elapsing between oxidation of the oil and subsequent testing, and markedly so by the method of extraction of the acidified alkali extract, the am ount of oxygen used, and the extent and nature of the copper surface used. The am ount of sludge produced is also affected by these factors. The following method is recommended for technical use. The oil (150 g.), contained in a 300-c.c.

Erlenmeyer flask, is immersed to a definite and fixed depth in an oil-bath maintained a t 120°. Oxygen, purified by passage through caustic soda solution and sulphuric acid, is passed a t the rate of 2 bubbles per sec. through a delivery tube opening a t 1 — 2 mm.

above the bottom of the flask. An open spiral of clean (unprepared surface), rolled, electrolytic copper foil (made from .a strip 1 0 0 mm. long, 1 0 mm. broad, and 01 mm. thick) is placed loosely around the delivery tube. After 70 lirs.’ continuous heating in the presence of the copper and oxygen, the oil is set aside overnight, well shaken, and 50 g. of it are refluxed for 20 min.

with 50 c.c. of a solution made by dissolving 75 g. of pure caustic soda in 1 litre of distilled water and mixing with 1 litre of 96% alcohol. Then 40 c.c. of the filtered alcohol-water layer obtained by separation are acidified with hydrochloric acid, mixed with 50 c.c. of distilled water, and the mixture is thrice extracted with 50 c.c. of pure, residue- and thiophen-free benzene.

The combined benzene extracts and benzene washings from the funnel are extracted with 50 c.c. of distilled water, and the benzene fraction is evaporated, the water eliminated from the residue by distillation with absolute or 96% alcohol, dried in the oven a t 105° for 10 min., and the cool residue weighed. The am ount of ta r (in g.) multiplied by 2-5 gives the percentage tar index (“ Verteerungszahl ” ). The amount of sludge formation may be determined gravimetrically by mixing 10 g. of the oxidised oil with 30 c.c. of standard petrol, filtering, washing the separated sludge with cold stan­

dard petrol till free from oil, dissolving the sludge in benzene, and weighing the benzene solution as above.

Some results of the methods applied to American and Russian oils are given. H. E. Bl a y d e n.

Wax from low -tem perature tar. J. D. Da v is

and K. M. Ir c y(Ind. Eng. Chem., 1931,2 3 ,186— 189).—

Wax isolated from low-temperature ta r derived from U tah coal proved to consist of a series of hydrocarbons in which penta- (m.p. 54°) and hepta- (m.p. 60°) -cosane predominated. Small amounts of soft wax and u n ­ saturated compounds were also present. The m.p.

of the wax (a superior grade of dry wax) was higher than those of marketable petroleum waxes. The physical constants of the crude and refined wax are given. Bituminous coals were found to yield a ta r of low wax content as compared with th a t of the U tah coal and the sub-bituminous coals. Carbonisation with steam tends to increase the wax in a tar.

H . S. Ga r l ic k. D istillin g naphthenic acids. I. Gu t t, L. I o a n e s - y a n , and G. N o v r u s k h a n o v (Azerbaid. Neft. Choz., 1930, No. 9, 138—139).—Crude oils, when distilled in a vacuum or in steam, afford distillates containing naph­

thenic acids having b.p. up to 50° above the b.-p. range of the respective petroleum fractions.

Ch e m ic a l Ab s t r a c t s. N ew typ e of Surakhani crude oil. L. Gukhm a n

and A. Plotko (Azerbaid. Neft. Choz., 1930, No. 9, 102—103).—Characteristics of a monoparaflinic crude oil which has a low asphalt content are recorded.

Ch e m ic a l Ab s t r a c t s. Cracking of hydrocarbons at tem peratures higher than critical tem peratures. R. H. McKe e

and A. S z a y n a (Ind. Eng. Chem., 1930,2 2 , 953—956).—

Gasolines, b.p. 120—160°, together with a number of pure hydrocarbons, have been cracked a t 405—450°, the process being followed by determination of the critical temperatures before and after cracking for several periods. For paraffin hydrocarbons and straight-run gasolines the change of critical temperature indicates th a t the cracking process is a linear function. Ordinary gasolines crack a t one rate, saturated hydrocarbons somewhat more rapidly, and unsaturated hydrocarbons still more rapidly. The results obtained are in disagree­

m ent with a common theory of cracking and with some common beliefs on the mechanism of cracking.

H. S. Ga r l ic k. Action of the catalysts ferric oxide and ferric chloride in the reactions of sim p le hydrogenating cracking of Ragusa oil. E. Sa l m o ir a g h i (Annali Chim. Appl., 1931, 2 1 , 27—38).—The Ragusa oil used in the experiments described had d15 0-9667, flash point 107°, and on analysis gave C 83-46, H 9-14, (O + N) 4-55, S 2-85% ; it was subjected to both simple and hydrogenating cracking with and without ferric oxide or chloride as catalyst. The influence of catalysts is similar to th a t observed by Kling and Florentin (cf. B., 1929,968). W ith simple cracking, cracking in presence of ferric oxide, and hydrogenating cracking in presence of ferric oxide, the residue a t the first distillation remains identical with the residue of the Engler distillation of the original oil. The cyclic hydrocarbon fraction undergoes condensation and resists the action of the heating. The results obtained on hydrogenation in presence of non-hydrogenating catalysts reveal the influence of the quantity of the catalyst, part of which is consumed by the sulphur and so excluded from the reaction ; when the residue is washed with solvents and treated with acid, hydrogen sulphide is evolved.

The optimum effect is obtained by hydrogenation in presence of ferric chloride, the percentage of light products obtained being 77-5% and th a t of residue

11-07%, which is probably able to undergo further hydrogenation. The analytical figures show th a t the hydrogen tends to displace a large p art of the sulphur from the lighter to the heavier fractions. The residues from the hydrogenations in presence of ferric chloride contain no coke and, after being washed with organic solvents, consist solely of catalyst converted into sulphide or oxide. T. H. Po p e.

Action of alkali hydroxides on elem entary sulphur and m ercaptans dissolved in naphtha.

V. Ve s s e l o v s k yand V. Ka l ic h e v s k y (Ind. Eng. Chem., 1931,2 3 , 181—184).—Potassium and sodium hydroxides in the anhydrous state and in solution or suspension in various organic solvents, e.g., absolute ethyl and isopropyl

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

Cl. I I . — F c rE L ; Ga s ; Ta b ; Mi s d e a l Oi l s. 375

alcohols, absolute ether, and commercial wopropyl alcohol, remove quantitatively sulphur and mercaptans from petroleum oil. Sodium hydroxide is the more effective for the removal of mercaptans and potassium hydroxide is the more reactive towards elementary sulphur, potassium thiosulphate, mono- and poly-sui- phides, and water being the products of reaction between potassium hydroxide in alcoholic solution and elementary sulphur dissolved in naphtha. Higher polysulphides are formed by the direct addition of sulphur to the lower sulphides, the trisulphide being the highest polysulphide found if the reaction mixture has not been agitated.

When the reagent is kept in intim ate contact with the sulphur solution, potassium penta- and possibly hexa- sulpliides are also to be found. The products of reaction between sodium hydroxide in alcoholic solution and mercaptans dissolved in naphtha are sodium mercaptide and water. Keeping any of the precipitated substances in contact with naphtha for a considerable length of time results in some of the sulphur being returned to the oil in elemental form, due to the oxidising effect of dissolved air in the polysulphides and thiosulphate and sodium mercaptide, respectively. H. S. Ga r l i'c k.

Adsorption and base exchange. P. G. Nu t t in g

(J. Washington Acad. Sci., 1931, 2 1 , 33—36).—Adsorp­

tion by sand and clay is discussed, particularly in relation to the filtration of crude mineral oils. Oil sands consist of quartz grains coated with ferrous or ferrous aluminium silicates and finally with hydrocarbons. I t is possible to remove the two layers successively. Sea sand may be activated by treating with alkali, acid, and water successively and then drying a t 200°. The activated product adsorbs all kinds of positive ions and colloidal aluminium hydroxide. A dry filtering clay gives a white filtrate from black petroleum, bu t a filter which is not thoroughly dried gives a yellow product.

E. S. He d g e s. S ynthesis of petroleum hydrocarbons from h y ­ drogen and carbon m onoxide at ordinary pressure.

II. K . Ko b a y a sh i, K . Yam a m oto, and H. Is h ik a w a

(Mem. Fac. Sci. Eng., Waseda, 1930, No. 7, 26—27).—

The synthesis is carried out using cobalt, cobalt- manganese oxide, and cobalt-copper-manganese oxide catalysts. I t is considered th a t cobalt and iron are primary catalysts, manganese oxide and alkalis acting as promoters eliminating carbon dioxide.

I n addition to the formation of methane carbon monoxide is considered to form carbon dioxide and active carbon, the latter forming ethylene and acetylene by hydro­

genation, and, by polymerisation and hydrogenation of the two latter compounds, higher hydrocarbons. The formation of methane cannot be prevented in favour of that of hydrocarbons, as the temperatures of reaction are similar (230—250°). E. A. Ry d e r.

D ecolorisation of petroleum w ith acid clay.

I—III. K. Yamamotoand H. Is h ik a w a (Mem. Fac. Sci.

Eng., Waseda, 1930, No. 7, 28—31).—I. The quality and fineness of an acid clay are shown to affect its decolorising power, air elutriation being suggested for use in preparation of the clay. Improved decolorisa­

tion results from finer sieving, but fine sieving alone will not render an inferior clay equal in performance to a

good natural clay. Decolorisation is not proportional to the acidity of the clay, but a relation may exist between acidity and fineness.

II. The acidity of acid clay decreases gradually on heating from 1 0 0° to 1 0 0 0°, being practically zero a t the latter temperature. The decolorising power of an acid clay is little affected by heating from 100—-250°, but decreases from 250° to 600° and falls off much more rapidly from 600° to 1 0 0 0°.

III. The acidity of clays is determined by direct neutralisation with standard alkali, and also by mixing the clay with standard neutral salt solution, such as an alkali chloride, followed by determination of the hydro- gen-ion concentration of the filtrate potentiometrically or by titration with standard alkali. Results obtained by the two methods are identical and the j>k values of many clays is found to be from i to 6. The acidity of clays is not found to increase when treated with various concentrations of hydrochloric acid, but the decolorising power does increase somewhat. The acidity decreases when treated with sodium hydroxide in proportion to the concentration of the alkali up to the point a t which the clay becomes neutral, whilst the decolorising power of the clay is decreased by this treatm ent. The acidity of the clay is reduced to the point of neutrality by tre a t­

ment with alkali chloride, but the decolorising power is approximately unchanged. E. A. Ry d e r.

D eterm ination of the carbon residue from petroleum products. (Carbon residue b y Conrad- s o n ’s m ethod.) B . Ro se n b a u m (Chem.-Ztg., 1931, 5 5 , 106; cf. B ., 1931, 101).—Conradson’s method (of 1927) is modified by the A.S.T.M. specifications of 1930.

The deviation of the present values of carbon residues of the standard Gargoyle Mobiloils from values found previously (cf. loc. cit.) amounts to about 37% of the experimental figure. The decrease is chiefly due to improvement in quality of the oils and not only to the modified method of determination. A proportionality exists between increase of viscosity and the amount of carbon residue from mineral o ils; comparisons of oils on the basis of determination of carbon residue should therefore be made only with oils of similar

viscosity. H. E. Bl a y d e n.

E stablishing the identity and purity of a hydro­

carbon obtained from petroleum . E. W. Wa s h b u r n

(Ind. Eng. Chem., 1930, 2 2 , 985—988).—The evidence in support of the identity and purity of most of the hydro­

carbons reported in literature as having been isolated from petroleum is critically examined and found to be inadequate. Suitable tests are described and a procedure suggested in which a t least the five properties—refrac­

tive index, density, b.p., f.p., and halogenation behaviour

—should be reported on all petroleum fractions for which identification is claimed. H. S. Ga r l ic k.

Com position and recovery of crude benzol produced under different carbonising conditions.

S. Tw e e d y(Gas World, 1931,94, Coking Sect., 15—18).—

Analyses, by Column's method, of benzols obtained from various systems of carbonisation show th a t variations in composition occur with coke-oven benzol, bu t to a smaller extent than those occurring in gasworks’ practice. Com­

parison of the composition of crude benzol produced at

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B r i t is h C h e m ic a l A b s t r a c t s — B .

376 Cl. I I . — Fü e l ; Ga s ; Ta r ; Mi n e r a l Oi l s.

different carbonising times on individual plants, and of the product from different types of ovens, shows th a t the coke-oven benzol is of varying composition, th a t short carbonising times on the same battery increase the benzene content, and th a t similar carbonising times on different batteries produce crude benzols of varying composition. Investigations of the factors influencing scrubbing efficiency show that, when using the theo­

retical quantity of scrubbing oil required to absorb the benzene, satisfactory absorption of benzene, toluene, and solvent naphtha is obtained a t temperatures up to 2 0° with efficient scrubbing. A t 30° absorption of benzene becomes inefficient, bu t absorption of toluene and solvent naphtha is still good. H. E. Bl a y d e n.

Determ ination of lead tetraethyl in anti-knock petrols by Vareton’s m ethod. G. We is s (Petrol­

eum, 1931, 2 7 , 113—114).—The substances in use as anti-knock materials arc reviewed and the methods of detecting and determining lead tetraethyl (cf., e.g., Toms and Money, B., 1928, 559) are discussed. Lead tetraethyl may be detected by soaking a filter paper in the petrol, exposing it until dry under the mercury- vapour lamp, treating with dilute acetic acid and then with hydrogen sulphide or potassium iodide. For its determination a method depending on its decomposi­

tion by acetyl chloride is recommended. The petrol

( 1 0 0 c.c.) is placed in a glass-stoppered flask, 2—3 c.c.

of acetyl chloride and 1 — 2 drops of water are added, and the mixture is well shaken and allowed to settle. After 4—5 hrs. the lead tetraethyl is thereby completely decomposed, and the precipitate is collected, washed with light petroleum, dissolved in nitric acid, and the lead determined as sulphate. H. E. Bl a y d e n.

[M ineral oil] sludge determ ination. L. Gu k h m a n

(Azerbaid. Neft. Choz., 1930, No. 5, 97-—100).—Errors arise from the high solubility of sulphuric acid in the diluent gasoline ; the use of gas oil is recommended.

Ch e m ic a l Ab s t r a c t s. Air in [Russian m ineral oil] refineries. I.

La p k in and G. Ego rova (Azerbaid. Neft. Choz., 1929, No. 1 2, 76—78).—Still-house air contained 16-7 mg.

(max.) of hydrocarbons per litre.

Ch e m ic a l Ab s t r a c t s. Knock-rating of m otor fuels. Su b-Co m m e e. o f

In s t it u t io n o f Pe t r o l e u m Te c h n o l o g ist s ( J . I n s t.

P e tr o le u m T e c h ., 1931, 1 7 , 69—71).—T h e r e p o r t o f th e S u b -C o m m itte e o n k n o c k - r a tin g s fo r 1929 s h o w e d t h a t th e g a so lin e s so ld o n t h e B ritis h m a r k e t g a v e c o m p a r a tiv e r e s u lts o n 3 d if fe re n t ty p e s o f t e s t e n g in e s. T h e e x te n ­ s io n o f t h i s w o rk to c o v e r m o re t y p e s o f g a s o lin e a n d b le n d s sh o w e d t h a t fu els r a t e d in te r m s o f p u r e h y d r o ­ c a rb o n s g a v e s o m e w h a t p o o r a g r e e m e n t in t h e c a se o f s tr a ig h t - r u n g a so lin e s a n d p ro n o u n c e d d is a g re e m e n t in t h e c ase o f n o n - s tr a ig h t- r u n fu els. T h e b o u n c in g - p in m e t h o d w a s t h e m o s t s a tis f a c to r y fo r m e a s u rin g k n o c k - in t e n s i ty o n s m a ll en g in es. O n t h e H o r n in g e n g in e s i’s o o c ta n e g iv e s m o re c o n s is te n t r e s u lts t h a n d o e s b e n z e n e , a n d i t is a g re e d t h a t k n o c k - r a tin g s s h a ll in f u t u r e b e e x p re s s e d in te r m s o f is o o c ta n e . C oil ig n itio n is p r e f e ra b le to m a g n e to ig n itio n a n d , p e n d in g th e a d o p ti o n o f s t a n d a r d e n g in e s , t h e te s ti n g e q u ip m e n t s h o u ld b e s u c h t h a t v a r ia b le c o m p re ssio n a n d th r o t t l i n g m e th o d s a r e a v a ila b le . T . A. Sm it h.

Vapour-pressure curves of m otor sp irits. P.

Me y e r (J. Inst. Petroleum Tech., 1931, 17, 42—68).—

From collected experimental data it is observed that the vapour-pressure curves of air-free motor spirits are all of the same type, a single curve based on the Ramsay- Young b.-p. law fitting the data. The true vapour- pressure curves agree with an apparent value of Trouton’s constant of 17-6. Vapour-pressure curves for pure hydrocarbons and the corresponding equations are given together with curves for air-free motor spirits as deter­

mined by four different methods. These results agree with the equation proposed by Bridgeman, Aldrich, and White, viz., log P = 6-76 — 3-8St/T, and also with the value 17-6 for Trouton’s constant. An alinement chart for use in connexion with evaporation losses, transport, and engine performance of light spirits is given. Available data for latent heat of vaporisation of petroleum fractions are graphed against the 50%

distillation temperature. From a knowledge of the mol. wts. of their fractions, the values of Trouton’s constant may be calculated ; these give a mean of 20-4—the value for pm e hydrocarbons.

T. A. Sm it h. Follow ing com bustion in the gasoline engine b y chem ical m eans. L . Wit h r o w, W . G. Lo v e l l, and T. A. Boy d (Ind. Eng. Chem., 1930, 2 2 , 945—951).—

Measurements have been made of the oxygen concen­

tration in gases withdrawn from the cylinder of a gasoline engine having an improved type of sampling valve, which was located a t different places in the combustion chamber and opened a t different times during the combustion of the charge ; the results are plotted against the respective angles of revolution a t which the samples were removed. Under the conditions defined, a narrow combustion zone passes through the charge of gasoline and air in the engine a t a finite velocity, which is faster in the middle portions than along the side walls of the combustion space. The speed of the combustion zone increases with engine speed. The forms of the steep parts of the oxygen curve are affected by several factors. Thus the longer the valve remains open the flatter is the curve, the slope of the curve varying with fluctuations in the rate of flame propagation between successive explosions. Other factors are : pressure changes in the combustion chamber during the interval the valve is open, time required for the combustion zone to pa,ss by the sampling valve, rate of combustion of the gasoline in the burning zone, quantity of oxidation taking place in the expansion chamber of the valve itself. The progress of combustion is unaffected by a change in spark timing or by the addition of sufficient lead tetraethyl to the fuel to stop detonation until after it has travelled the greater portion of the distance across the combustion chamber. Knock or detonation is confined to th a t p art of the charge which burns last. H. S. Ga r l ic k.

Chem ical structure of lubricating o ils. G. H. B.

Da v is and E. N. McAl l is t e r (Ind. Eng. Chem., 1930, 2 2 , 1326—1329).—A correlation of data on paraffin and c/ycZoparaffin hydrocarbons has indicated th a t the relation of mol. vol. to mol. wt. offers a means of estimating the relative proportions of these compounds in petroleum products. This relationship has been expressed in the

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