British Chemical and Physiological Abstracts. B. Applied Chemistry, August

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B.—A P P L I E D C H E M I S T R Y AUGUST, 1938.


Im p rovem en ts in d esign and con struction of rotary-hearth furnaces. D. P. Ar m b r u s t e r

(Ind. Heating, 1937, 4, 1110—1114).—A new type of H 20-sealed hearth construction is described.

R . B. C.

Causes and prevention of defects in h ot-b last sto v e s. H. Sc h u m a c h e r (Stahl u. Eisen, 1938, 58, 372—377).—A survey is given of experience gained in the working of hot-blast stoves together with details of th e dimensions, stove linings, etc. Difficulties were first encountered as a result of excessive dome tem p, consequent on rapid heating. These are over­

come by tem p, control by means of a P t/P t-R h thermocouple. Details arc given of tho destruction of the chequerwork lining, owing to failure to allow for its expansion, and certain measures are recom­

mended. Tho detrim ental shortening and deflexion of tho combustion chamber is attrib u ted to tho shrinkage and softening of tho bricks a t high tem p.

Reference is m ade to tho deterioration of the steel casing, and methods of counteracting it are suggested.

C. M. A.

S o-called th erm a l effect and true tem perature of catalytic conversion. M. Ja k o b (Trans.

Amer. Inst. Chem. Eng., 1938, 34, 173— 179).—An arrangement of three concentric tubes, in which the outside surface of the centro tube and the inside surface of the m iddle tube aro coated with a catalyst under observation, is suggested as a means for in ­ vestigating the tem p, rise dining the progress of a catalysed reaction. I t is suggested th a t by the use of such an apparatus it will be possible to assess the therm al effects of catalysts with duo consideration for therm om etric requirements. F . J . B.

H eat exch an gers for ch em ical p rocess applic­

ation s. K. B. Mtllett (Ind. Eng. Chem., 1938, 30, 367—372).—The modifications to the design of tub ular heat interchangers when intended for corrosive and d irty conditions on one side or on both sides of the m etal, for high-pressure operation etc., are considered, gleans for minimising leakage past baffies, providing extended surface to compensate for low heat-transfer coeffs., and a tubular construction without a shell for exceptional conditions are indicated.

A table showing the relative heat transfer achieved per unit of purchase price for .a wide range of duties

is given. F. J . B.

A pplication of h eat to syn th etic organic p ro cesses in th e ch em ical in d u stry. H. Ar g a n t

(Tech. Ind. Chim., 1938, No. 277 bis, 136— 142).—

Different types of m odem heating systems and heated vessels are described. ' I. C. R.

M ean tem p eratu re-d ifierences correction in m u lti-p ass exch an gers. F . K . F i s c h e r (Ind.

Eng. Chem., 1938, 3 0 , 377—383).—I t is pointed out th a t there is a discrepancy between the actual mean tem p, difference in a multi-pass heat exchanger and the log mean temp, difference derived from the inlet and outlet temp, which does not lend itself to a simple mathem atical solution. Starting w ith Underwood’s analysis of the simpler cases, correction factors are worked out and tabulated for a large no. of arrange­

ments. F . J. B.

T estin g h eat-tran sfer eq u ip m ent. R . C.

G u n n e s s and J. G. B a k e r (Ind. Eng. Chem., 1938, 3 0 , 373—376).—The theoretical basis for, the practical means of evaluating, and th e methods of interpreting th e figures for th e duties of heat inter changers aro

disoussed. F . J. B .

T em perature m easu rem en t w ith th e th erm o­

couple. H. De Ry c k e r (R e v . Univ. Min., 1938, 14, 299—307).—The error duo to voltage drop in tho thermocouple and lead is compensated for by means

of a shunt resistance. R . B. C.

B a se-m eta l th erm ocou p les : th eir character­

is tic s . M . R . Ma n d l e k a r and H. N. Ba n e r j e a

(Current Sci., 1938, 6, 447—448).—Nichrom e- constantan couples are trustw orthy for temp.

>800°. The thermo-e.m.f. relationship is practically linear, and the e.m.f. obtainable is as wide as th a t with F e - and Cu-constantan couples. The irregularity obtained between 250° and 400° in the thermo- e.m.f. curves of thermocouples containing Ni disappears in the Constantan couples. The neutral points for Fe-nichrome and Cu-Fe couples lie a t 205° and 275°,

respectively. L. Si T.

R eference tab les for ir o n - and cop p er-con - stan tan th erm ocou p les. W. F . R o e s e r and A. I.

D a h l (J. Res. N at. Bur. Stand., 1938,2 0 ,337—355).—

E .m .f.-tem p. reference tables for th e selection of thermocouple m aterials are given for F e-constantan from —200° to 1000° and for C u-constantan from

—200° to 400°. Average vals. aro also given for tho e.m.f. vals of Cu, Fe (which is generally available), and constantan against P t ; tho variations in e.m.f. th a t might be expected from different samples of these materials are indicated. D . F . R .

M otion of a flu id h eated from b elow . R . J.

So h m id t and O. A. Sa u n d e r s (Proc. Roy. Soc., .1938, A, 165, 216—228).—A horizontal layer of fluid is heated from below and the onset of cellular and turbulent m otion is recorded by an optical method.

A h and H 20 are investigated. In cellular motion the length of the side of the cell is twice the depth of the 853


layer. The rate of heat transfer through the layer

is measured. G. D. P.

D ry in g m a te r ia l in tr a y s . E v a p o ra tio n of su rfa c e m o is tu r e . C. B. Shepherd, C. Hadlock, and R. C. Brewer (Ind. Eng. Chem., 1938, 30, 388—297).—A report is given of an experimental investigation into the rate of evaporation of H 20 from trays of sand of two grades over ranges of air tem p., hum idity, and velocity, and depth of bed.

The results are correlated and shown to agree with corresponding figures for the evaporation from plain

H 20 surfaces. E. J . B.

E ffectiv e d r u m d ry in g . G. N. Harcourt

(Chem. Met. Eng., 1938,. 45, 179—182).—Different types of drum dryers, including one operating under vac., are described and illustrated and their perform­

ances given. D. K. M.

R e frig e ra tio n in c h e m ic a l e n g in e e rin g . G. W.

Da n i e l s (Proc. Chem. Eng. Group, Soc. Chem. Ind., 1937, 19, 129— 138).—The physical laws governing the artificial production of cold and the factors to be considered before incorporating a refrigeration plant in a process are enumerated. Various types of vapour-compression and absorption plant are described and compared; m ultistage cooling, choice of cooling agent, and general m ethods of operation are described.

A. K . G. T.

R e frig e ra tio n b y e v a p o ra tio n of w a te r u n d e r re d u c e d p r e s s u r e . A . An t o n i (Compt. rend.

X V II Cong. Chim. Ind., 1937, 4 0 0 -4 1 2 ).—I t is pointed out th a t for a h conditioning and similar apphcations where cooling rather th an true refriger­

ation is required it is possible and desirable to use H 20 as the fluid. Illustrated descriptions of two types of plant, one using je t and the other multistage centrifugal compressors, are given and some industrial

applications noted. F . J . B.

H e a t-tre a tin g of [stee l] b o ile r tu b e s . J . M.

Brow n (Iron Age, 1938, 141, No. 9, 50—51).—A surface-combustion, continuous furnace for normalis­

ing, annealing, and blueing boiler tubes is described.

R adiant-tube heating is employed, the atm . in the heating and cooling zones being cracked natural gas.

R . B. C.

S z ik la -R o z in e k s y s te m of [b o iler] firin g . G. Szikla and A. Ro zinek (Feuerungstech., 1938, 26, 97—112).—Coal of 0—5 mm. size is coked in a gas stream and the coke then gasified in a separate shaft from which the gases pass to the combustion chamber. A diagram matic description is given of a H 20 -tub e boiler fired by this method. Any type o f coal can be employed. R . B. C.

D e p en d en ce of tb e h e a t- tr a n s m is s io n coeffici­

e n t in [an e x h a u s t- s te a m b o ile r] w a te r p r e h e a te r o n th e r m a l lo a d on th e h e a tin g su rfa c e . K.

Sc h iebl (Warme, 1938, 61, 298—300).—The data obtained b y K amm erer (cf. B., 1938, 1) are critically

discussed. R . B. C.

In te r c ry s ta llin e c ra c k in g i n b o ile r s te e l. W. C.

Sch ro eder, A. A. Be r k, and C. H . Fellows (J.

Amer. W ater Works Assoc., 1938, 30, 679—694).—

The mechanism of intercryst. cracking has been investigated. I t appears to be a selective corrosion

process depending on the chemical composition of the boiler H 20 and the stress conditions of the metal.

Externally-applied stress is no t a necessary factor, nor can internal stress alone, H 2, or corrosion-fatigue produce it. Lignin and other org. m aterials give more protection th an does N a2S 0 4. O. M.

C o rro s io n of s te a m b o ile rs a n d fo r m a tio n of o il-b e a rin g scale a f te r feed in g w ith oily c o n d e n se r w a te r. H. Ditz and F. Ullrich (Korros. u. M etall­

schutz, 1938, 14, 141— 150).—Scale removed from a corroded boiler and preheater which had been fed with oily H 20 from the condensers contained appreciable quantities of oily m atter, some of which was sol. in CHC13 (unchanged lubricating oil) and some present as a Ca soap; of the latter, p a rt appeared to be derived from oxidation of the oil and could be extracted with CHC13 after, treating the scale with HCl, and p art from therm al decomp. of the oil or its oxidation products and could be extracted from the acid-insol. m aterial by dil. aq. NaOH. Tests with mineral oil showed it to have no corrosive action unless it were oxidised; th e oxidised oil adheres as a ta rry film to, the steel and entraps 0 2 liberated from the H 20 , and this sets up local pitting.

P itting is th en accelerated by therm al decomp. of the ta rry m atter which gives rise to acids which slowly attack th e steel. The nature o f th e scale deposited from the H 20 has an appreciable influence on th e corrosive action of the oily m atter, a high SiOa content generally being more dangerous th an a

high CaC03 content. A. R. P.

C o rro s io n of in te r n a l p a r t s of h ig h -p re s s u re b o ile r fe e d -w a te r p u m p s . G. We y l a n d (Warme, 1938, 61, 379—382).—Photographs show the damage to feed-H20 pumps resulting from tho use of corrosive H 20 . The p a of the H 20 should be > 8 , otherwise corjpsion-resistant m etal m ust be used in the con­

struction of the pump. R . B. C.

C o n tro llin g c o rro s io n i n s te a m a n d [ s te a m - co n d e n sa te ] r e tu r n lin e s [of b o ile rs ]. M. E.

Dr e y f u s (Power P lan t Eng., 1938, 42, 274—275).—

Volatile amines (Coravol) are added to the boiler- H 20 with th e object of m aintaining alkalinity in the steam and the condensate. R. B. C.

C o m b in e d p ro d u c tio n of p o w e r a n d s te a m fo r h e a tin g p u rp o s e s in th e c h e m ic a l in d u s try , a n d th e c o n s id e ra b le ec o n o m ie s w h ic h c a n r e s u lt. E. La pe y r e (Tech. Ind. Chim., 1938, No. 277 bis, 130—135).—The advantages of using exhaust steam for heating purposes are discussed and typical installations described. I. C. R.

R e m o v a l of s ilic a fro m w a te r fo r b o iler-feed p u rp o s e s . M. C. Schwartz (J. Amer. W ater Works Assoc., 1938, 30, 659—678).—S i0 2 can be removed by use of Fe111 salts, especially F e2(S04)3, with alkaline-eartli and alkali-metal compounds, the optimum p a being 8-5—9-5 for the particular waters studied. The process can be carried out alone, or in conjunction with cold- or hot-process chemical Softening, adding the Fem salts with the softening reagents and any coagulant norm ally in use, provided th a t tho proper p n is maintained. I f S i0 2 is removed before base-exchange softening is effected, only non-


Cl. I.—GENERAL; PLANT; MACHINERY. 855 siliceous base-exchange compounds m ust be used, to

avoid redissolution of S i0 2. Ee111 treatm ent should n o t follow base-exchange softening as the Ca etc.

required for proper coagulation of the Fe111 will then be absent. Fem salts with alkali aro more efficient th an is prepared Fe(OH)3. The resultant sludge can be used again after acid (to p n 2—3) or alkali (pa 11) treatm ent. The removal of S i02 is governed by the chemical characteristics of th e H 20 , so th a t each requires individual treatm ent. 0 . M.

C h em ical c o rre c tio n of w a te r u s e d in co o lin g s y s te m s . L. D. Betz (Oil and Gas J ., 1938, 36, No. 49, 60, 62, 65, 69).—The val. of treatm ent by H 2S 0 4, CaO, and zeolites is discussed in connexion with the treatm ent of a H 20 containing high [Ca**]

and [HC03'J. In each case the reactions involved are reviewed and the economics of the process outlined.

J . W.

C o rre c tio n of coo lin g w a te r fo r p re v e n tio n of sca le , c o rro sio n , a n d o rg a n ic g ro w th s . L. D.

Betz (Refiner, 1938,17, 202—206).—A review.

R. B. C.

D e g a ssin g of b o ile r fe e d -w a te r to p re v e n t c o r­

ro s io n a n d p ro te c tio n of th e w a te r fr o m g a s a b s o r p tio n . 0 . T. Koritnig (Korros. u. M etall­

schutz, 1938, 14, 151— 154).—Several modern methods are described and their advantages and disadvantages are discussed briefly. A. R . P.

E le c tro ly tic c o n tro l [of b o ile r sc a le ] d e c re a se s [b o iler] m a in te n a n c e . C. Hammond (Power P lan t Eng., 1938, 42, 2Q6—208).—An application of th e Kircaldy m ethod of preventing corrosion and scale formation in boilers is described. B y placing in ­ sulated anodes in the boiler H 20 the heating surfaces

are made cathodic. R. B. C.

F ig h tin g c o o lin g -p o n d algaa. E . Sterrett

(Power P lant Eng., 1938, 42, 175— 176).—Applic­

ation of hot aq. CaS04 to the surface of the H20 prevents the growth of algae. R, B. C.

Z e o -K a rb H . N ew m e th o d of c o n d itio n in g w a te r to re m o v e s o d iu m b ic a rb o n a te c h e m ic a lly in s te a d of b y d is tilla tio n . S. B. Applebaum

and R. Riley (Ind. Eng. Chem., 1938, 30, 80—

82).—A plant in which N aH C 03 and N a2C 03 are completely removed from well-H20 containing 705 and 42 p.p.m., respectively, by passage over Zeo- K arb H, a zeohte o f carbonaceous origin, is described.

Residual acidity due to Cl' and S 0 4" is neutralised by adm ixture of 20% of the raw H 20 . H 2S 0 4 is used for regeneration. In the Na cycle, Zeo-Karb m ay be used for softening boiler-H20 where absence of S i0 2 is an advantage. I. C. R.

O p e ra tin g ex p e rie n c e s in th e s te a m a n d p o w e r d e p a r tm e n t of tb e a lk a li p la n t of tb e S o u th e rn A lk a li C o rp o ra tio n . G. R. Avery (Trans. Amer.

Soc. Mech. Eng., 1937, 59, 535—539).—The boiler feed-H20 is obtained by treating crude river-H20 with C a0-N a2C03 followed by N a2H P 0 4. A con­

siderable reduction in the costs of boiler maintenance has been effected by this method of H „0 treatm ent.

R . B. C.

C h lo rin a tio n of coo lin g w a te r s . N. C. Estes

(Refiner, 1938, 17, 191— 197).—Addition of Cl2 to

the cooling-H20 systems of heat exchangers for the purpose of preventing slime form ation and reducing heat-transfer losses is discussed. Various types of chlorination arrangem ent are illustrated.

R. B. C.

D e te rm in a tio n of d isso lv e d s o lid s in b o ile r w a te r b y d e n sity re a d in g s . J . K. Rummel and J . A. Holmes (Trans. Amer. Soc. Mech. Eng., 1936, 58, 217—221).—H ydrom eter testing methods are

compared: Ch. Abs. (p)

T h e o ry fo r s u rfa c e [s te a m ] c o n d e n se rs . C.

Cabanes (Genie Civil, 1938, 112, 269—272).—The theory is applicable to a condenser in which steam is oondensed a t th e lowest possible pressure compatible with the tem p, and flow of the circulating H 20 . Formulas for changes in temp, and pressure are developed and applied to a condenser with a surface

of 1000 sq. in. R. B. C.

H e a t tr a n s f e r in th e c o n d e n sa tio n of s te a m . M, Fishenden (Engineering, 1938, 145, 643—645).

—Steam condenses to form a film on clean and slightly roughened surfaces which are in a “ w ettable ” con­

dition, whereas th e condensation is in the form of drops on highly polished and greasy surfaces. The heat-transfer coeffs. for condensation in drops are 5—7 times as large as the corresponding coeffs. when a continuous film is formed. Since in modern con­

denser practice the heat-transfer coeff. when steam is condensed to a film is of the same order of magnitude as th a t on th e H 20 side, which can be increased only a t th e expense of high H 20 velocities, th e possible gains by inducing condensation in drops are a ttra c ­ tive, Small am ounts of air in th e steam affect the heat transfer adversely; thus 1% of air reduces the

coeff. by 67%. F . J . B.

P a rtic le size re d u c tio n a n d s e p a ra tio n . W. H, Coghill and F . D. DeVaney (Trans. Amer. In st.

Chem. Eng., 1938, 34, 113—129).—A broad survey o f crushing and grinding processes is followed by a discussion of some investigations into ball milling, rod milling, and roll grinding. The. increasing use of screens, classifiers, and elutriators working in co­

operation with grinding plants is considered, and it is pointed out th a t the tendency is tow ards th e grading of the “ sub-sieve ” sizes. The influence of moisture content on the separation of the finer grades is indicated by the results of tests on a plant screening to 10-mesh an ore containing 2-2% o f moisture, which showed th a t of th e minus 65-mesh m aterial only 49%

was removed. F . J . B.

S ize re d u c tio n b y im p a c t. J . T. Fowler (Chem.

Met, Eng., 1938, 45, 230—233).—Use of swing-ham- mer mills is advocated for the coarse breaking, fine crushing, or shredding of m aterials varying from hard and abrasive m aterials to resinous and fibrous org.

m atter. F. J . B.

M ec h an ical d is in te g ra tio n of s o lid s . J . Auma- r e c h a l (Compt. rend. X V II Cong. Chim. Ind., 1937, 942—946).—I t is claimed th a t finer grinding th an is obtained in existing “ colloid ” mills can be carried out in a suitably designed and operated roll mill.

Stress is laid on the need for a suitable m aterial of construction and for the attainm ent o f highly finished


roll surfaces, whilst the roll pressures should he high.

The operating modifications include the adjustm ent of the relative speeds of the rolls to suit the hardness o f the m aterial to be ground, and th e application to th e roll surface of an extremely th in film of some m aterial such as glue w ithout undue cushioning.

Careful control of the ra te of feed and a suitable means for the removal of the disintegrated m aterial

m ust be provided. F . J . B.

D e v e lo p m e n ts in c r u s h in g a n d p u lv e ris in g e q u ip m e n t. L. T. Work (Trans. Amer. Inst.

Chem. E ng., 1938, 34, 101— 111).—An illustrated description is given of recent modifications in the design and operation of crushing and grinding plant.

The changes in th e design are in the direction of th e more effective use of th e grinding forces while reducing energy consumption and minimising th e wear on the working surfaces. Special note is m ade of the Y ibratom (a vibrated, b u t no t rotated, ball mill) and je t mills as novel fine-grinding plants of which in ­ sufficient operating d ata are as yet available. The preconditioning o f m aterials to increase their grind­

ability, and addition of dispersing agents to create colloidal dispersions ra th e r th an agglomerates, are mentioned. A ttention is drawn to improvements in auxiliaries such as classifying systems and autom atic control of th e ra te of feed. " P . J . B.

P u lv e ris in g 200 p ro c e s s m a te r ia ls . An o n. (Chem. Met. Eng., 1938, 45, 241, 242).—A tabulated analysis is m ade of returns from 43 m anufacturers, showing the types of disintegration equipm ent which have been successfully apphed to th e coarse, inter­

mediate, and fine-size reduction of 214 commercial

m aterials. p . J . B.

J e t p u lv e ris in g . M. A. Lis sm a n (Chem. Met.

Eng., 1938, 45, 238—239).—J e t pulverisers are 12—

36 in. in diam eter and 1—2§ in. in axial height a t the periphery, where compressed air a t 100 lb./sq. in. or superheated steam a t 100—500 lb./sq. in. is intro ­ duced horizontally through jets a t such an angle th a t the contents of the grinding chamber are sub­

jected to both swirl and im pact. The fluid leaves by an upper concentric outlet of the diam eter of th e grinding chamber, and the bulk of th e product is collected in a lower concentric tube J of the diameter.

W ith feed m aterials of $•—J in. and products with upper limits of 20— 2 y.. th e steam consumption ranges from 1 to 10 lb. of steam per lb. of product.

F . J . B.

B a ll-m ill g rin d in g . W. H . C o g h i l l and P. D.

Dev a n ey (U.S. Bur. Mines, Techv Paper 581, 1937,

56 pp.).—In a rod mill using tubes of the same dia­

m eter and loaded to give an effective d range of 2-89—7-30, the lighter rods are the less effective in crushing the coarser m aterial in the feed, b u t tend to produce more of the exceedingly fine products. In one batch test on a cylindrical ball mill, 19 X 36 in., the power consumption decreased progressively as grinding continued and the max. particle size in tho mill was reduced. F or the same mill operating a t 40% crit. speed, increasing grinding efficiency is associated with increasing dilution of pulp over the range 80—20% of solids in the batch. W ith open- circuit grinding this is no longer true. A rod mill

operated on open circuit shows a progressive increase in efficiency w ith increasing speed up to 60% of the crit., b u t a m arked fall a t 70% of th e crit. speed with either a large or small discharge opening. The larger discharge opening requhes more power to the extent o f about 2% a t all speeds. B atch tests on th e rod mill indicate optimum grinding conditions with an ore charge of 25 lb. when 39 lb. of dry ore are required to fill th e interstices of th e load of rods when a t rest.

W hen th e am ount of ore in th e mills is the same no appreciable difference is found between batch and continuous open-circuit ball-mill grinding. Increas­

ing rod diam eter gives increasing efficiency and small rods give better selective grinding th an large balls.

B atch ball-milling tests on the 19 x 36-in. m ill show greatest capacity over th e ore-charge range 50—75 lb. when 72 lb. are required to fill the interstices of the ball load a t r e s t ; highest efficiencies are obtained over the range .150—200 lb. F or dry ball milling, 75 lb. o f ore and about 80% of the crit. speed give th e optimum results. Under comparable conditions, w et grinding perm its greater capacity and higher efficiency th an dry, either in batches or in continuous operation;

Ni-hard balls gave the best results, especially when grinding hard chert, being followed in order by cast- Fe balls, porcelain balls, reject balls, pebbles, tetra- hedra. Concentric drum s , in a ball mill reduce the capacity without increasing efficiency. “ Rationed ” ball loads, in which th e am ount of each size of ball in the load is made oc th e am ount of m aterial of appro­

priate particle size in th e charge, show b etter effici­

encies th an “ Davis ” ball loads apportioned in accordance w ith the wear On th e balls. F . J . B.

G rin d in g in clo sed c irc u it. H . W. Hi t z r o t

(Chem. Met. Eng., 1938, 45, 234—235, 243).—The rechculation of th e oversize product separated by means of a classifier increases th e ou tp ut of a mill b u t reduces th e am ount of superfine m aterial produced, thu s minimising the power requirements for a given

size specification. F . J . B.

6 5 -m e sh g r in d in g in clo sed c irc u it w ith s ta in ­ le s s s te e l s c re e n s . W. M. St e p h e n (Amer. Inst.

Min. Met. Eng;, Tech. Publ. 901, 5 pp. ; Min. Tech., 1938, 2, No. 3).'—Tests m ade on one of four rod-mill grinding units dem onstrated th a t the rake classifier used in circuit w ith the mill could be replaced by screens of suitable dimensions. Screens made of ordinary m ild steel failed, due to blinding w ith rust, within 40 hr., b u t when m ade of stainless steel the life was of the order of several m onths and th e feed m aterial passed them freely. Costs are in favour of screens for this duty, bu t it is pointed out th a t since the screen takes no account of differences in d th e classifier m ay have technical advantages in m any m etallurgical operations where differential grinding is

requhed. F. J . B.

L o w -te m p e ra tu re g rin d in g . S. B. Kanowitz

(Chem. Met. Eng., 1938, 45, 236—237).—The mill and/or th e m aterial m ay be cooled, resulting in greater ou tpu t and lower power consumption. The feed m ay be mixed with solid C 02 or liquid ah , and the m ixture pulverised. Materials which are sticky a t room tem p, or a t th e temp, of pulverising m ay be successfully

ground in this way. F . J . B.


Cl. I.—GENERAL; PLANT; MACHINERY. 857 V iew of g r in d in g fu n d a m e n ta ls . W. L. M a s­

son (Chem. Met. Eng., 1938, 45, 226—229, 282).—

A survey of the influence of th e abs. size and size distribution required, size o f th e feed, mill speed, type of liner, wt. of charge, size o f media, flow rate, etc. on fine grinding, particularly in ball and rod mills.

F. J . B.

E ffect of g r in d a b ility on p a rtic le -s iz e d is t r i ­ b u tio n . R . M. Hardgrove (Trans. Amer. Inst.

Chem. Eng., 1938, 34, 131— 152).—Grindability is defined as the index representing the tons/hr. which can be pulverised to a stated fineness on a given pulveriser, so th a t crushing-resistance becomes lOOrf-H grindability. Figures for a wide range of materials are given; these vary from 2 for oat hulls to 204 for shale. Tho results of investigations, given in the form of curves, show th a t, in general, more surface is produced for a given overall fineness of grinding the lower is tho crushing-resistance of the m aterial.

The type of plant employed and tho m ethod of operating it have a minor influence on the particle- size distribution, i.e., on the surface produced when compared with the effect of crushing-resistance.

F. J . B.

G rin d a b ility v e rs u s m ill c a p a c ity . An o n. (Chem. Met. Eng., 1938, 45, 240, 285).—The capacities of ball-and-race pulverisers are nearly oc tho Hard- grovo grindability nos., which are defined by the output of a standard ball-and-race mill operated for a standard no. of revolutions. H ardgrove nos. for 29 representative materials are given. F. J./B .

P a r tic le m e a s u r e m e n t p ro b le m s . L. T. Work

(Chem. Met. Eng., 1938, 45, 247—249).—Sieving, sedimentation, microscopy, turbidity, adsorption, etc. are discussed as means of size analysis of various ranges of particle dimension. F. J . B.

M ix e rs in tb e p ro c e s s in d u s tr ie s . G. MacLe a n

and E. J . Lyo n s (Ind. Eng. Chem., 1938, 30, 489—

492).—The wide range of mixing problems and the difficulties involved in the change of scale from pilot to production p la n t. are discussed. I t is stressed th a t the only safe procedure with such problems is to rely on the experience of specialist m anufacturers.

F. J . B.

P ro p e lle r-ty p e m ix e r s . E . S. Bissel l (Ind.

Eng. Chem., 1938, 30, 493—496).—The adaptability of propeller-type mixers which perm it their use with any reasonable containing vessel, w ithout producing

“ swirl,” is considered. The upper limit of vj a t which the power requirements m ilitate against tho use of a propeller is claimed t o bo about 3600 centipoises.

The m aterials of construction m ust be selected to

w ithstand corrosion. F . J . B .

P e rfo rm a n c e of m ix in g e q u ip m e n t. R . C.

Gtjnness and J . G. Ba k er (Ind. Eng. Chem., 1938, 30, 497—500).—Although mixing equipm ent has been examined by studying the ra te of dissolution of suspended solids and their local concn., the time taken for uniform conductivity to be achieved after addition of an electrolyte, optical methods, and power absorp­

tion, no abs. or even generally acceptable criteria of performance have been adduced. I n spite of this drawback and the consequent absence of m athe­

m atical correlation, some of these research methods are applicable to the testing of production-scale plant.

F . J . B.

P r o g r a m m e fo r m ix in g s t u d y . K . S. Va l e n­ t in e (Chem. Met. Eng., 1938, 45, 244—256, 285).—

I t is indicated th a t standardisation of plant and measurements are necessary before substantial progress can be made in the investigation of mixing as a general problem. ^ F. J . B.

F lo ta tio n a n d a g g lo m e ra te c o n c e n tra tio n of n o n -m e ta llic m in e r a ls . 0 . C. Ralston (U.S.

Bur. Mines, R ept. Invest. 3397, May, 1938, 63 pp.).—

Existing plant and practice for flotation of coal, carbonaceous m atter, bituminous sands, salt crystals suspended in th e mother-liquor, quartz, clay, and various minerals and ores are reviewed. The selective agglomeration of granular mineral particles for separ­

ation on tables etc. and tho application to phosphate, limestone, sol. salines, kyanite, fluorite, and “ Trent coal amalgam ” are described. An extensive biblio­

graphy is included. S. J . K.

F lo ta tio n s e p a ra tio n of n o n -m e ta ls . 0 . C.

Ralston (Chem. Met. Eng., 1938, 45, 268—269, 281).

—Various applications of flotation, e.g., for separating NaCl and KC1 crystals, are briefly indicated and suitable forms of apparatus shown. (Cf. preceding

abstract.) F . J . B.

P re c is e m e th o d fo r s ie v in g a n a ly s e s. M.

We b e r, jun., and R. F. Mo ran (Ind. Eng. Chem.

[Anal.], 1938, 10, 180— 184).—Testing sieves, even though th ey m ay conform to A.S.T.M. specifications, should be calibrated, and methods of calibration by checking on standard samples are, in general, un­

satisfactory. The m ethod developed for determining microscopically the effective opening of plain-weave sieves shows th a t this val. is independent of tho size distribution of th e m aterial under test. The m ethod corrects for tho deviation of the average opening from the nominal and for the variations between th e individual openings of a single sieve. W ith tWill- weave sieves, however, discrepancies remain.

L. S. T.

P u m p s a n d fittin g s fo r c o rro s iv e liq u id s . F . R. Lorenz (Z. Ver. deut. Ing., Beih. Verfahrens­

tech., 1938, 1— 13; Z. Ver. deut. Ing., 1938, 82, 379—381).—An illustrated review. The corrosion- resistant properties of various constructional m aterials

are tabulated. R. B. C.

M e a s u re m e n t of flo w in g m a te r ia l in p ip e lin e s a n d op en ch a n n e ls. H. L o h m X n n (Arch. Tech.

Mess., 1938, No. 80, 15t).—A review. R. B. C.

P ip e -lin e co n n e x io n s. C. E . Gr e e n (Proc.

Chem. Eng. Group, Soc. Chem. Ind., 1937, 19, 117—

124).—An illustrated paper dealing w ith some of the joints found in general engineering pipe-line in­

stallations. A. K . G. T.

T ec h n iq u e of s e ttlin g s e p a ra tio n s . A . An a b l e

and C. L . Kn owles (Chem. Met. Eng., 1938, 45, 260—263, 283).—Continuous thickeners, hydro- separators, and classifiers all depend on the same fundamental principles. Stokes’ law does not apply, owing to hindered settling conditions, and capacities are based on an empirically determined settling rate


which m ay v ary from 1 to 30 times w ith m aterial apparently prepared in the same way. F. J . B.

C h a ra c te r of w oven filte r m e d ia . R. 0 . Prior

and R. G. Walker (Chem. Met. Eng., 1938, 45, 250—252).—Plain, twill, and chain weave show decreasing mechanical strength and increasing porosity, in th a t order. Selection of suitable fabric m ay depend on the physical lim itations imposed by the m aterial to be employed to w ithstand corrosive

conditions. F . J . B.

U se of m e ta llic filte r c lo th . An o n. (Chem.

Met. Eng., 1938, 45,'253).—M etallic cloths are used on account of their superior resistance to heat and corrosion, b u t owing to large exposed surface and fine voids the permissible degree of corrosion is low. The coarser weaves are used in conjunction with filter aids.

F . J. B.

S u p e r- filtra tio n b y d ia ly s is . H . P. Bassett

(Chem. Met. Eng., 1938, 45, 254—255, 285).—The membrane for dialysis should be th in while possessing sufficient mechanical strength. A ttem pts to rein­

force suitable membranes lead to serious reduction of

effective area. • F . J . B .

F iltr a tio n . A c cu rac y of p re d ic tio n of p la n t o p e ra tio n fr o m t e s t d a ta . E . L. McMillen and H . A. Webber (Ind. Eng. Chem., 1938, 30, 708—

716).—Predicted vals. for plant-scale plate and rotary vac. filters, based on d ata obtained on a small filter press using the R u th equations (cf. B., 1935, 753), arc in close agreement with actual vals. obtained for CaC03 sludge (2—54% of sohds) and for sludge obtained by neutralising H 3P 0 4 with soda ash.

Accurate predictions aro possible when pressure, temp., and sludge concn. are very different from those of the te st filtration. W ith thick sludges exact knowledge of the val. of the w t. ratio of the wet to dry cake is necessary since a slight error results in a large error in the ratio wt. of filtrate/w t. of dry solids.

I. C. R.

T re n d s in c e n trifu g a l s e p a ra tio n . C. M.

Ambler, jun. (Chem. Mot. Eng., 1938, 45, 256—

259).—An illustrated description is given of the range of centrifugal separators from an ultracentrifuge operating a t 100,000 r.p.m. on a 2-in. radius to an autom atic bulk centrifugal with a 42-in. diameter rotor running a t 1900 r.p.m . F . J. B.

D e sig n a n d c o n s tru c tio n of re c tific a tio n a p p a r ­ a tu s . H. Canzler (Z. Ver. deut. Ing:, 1937, 187—- 189).—Practical experience regarding suitable shapes of bubble cap ai!d methods of fastening them is

summarised. R. B. C.

D is tilla tio n a n d re c tific a tio n . Im p o rta n c e of th e s e o p e ra tio n s in th e m a n u fa c tu re of c h e m ic a l p ro d u c ts b y m o d e m m e th o d s . H. Gu in o t

(Tech. Ind. Chim., 1938, No. 277 bis, 151— 162).—

The theory of distillation is reviewed and several

examples are discussed. I . C. R.

P e rfo rm a n c e of b u b b le -p la te c o lu m n s. F r o th h e ig h ts a n d p r e s s u r e d iffe re n tia ls . M. Souders, jun., R. L. Huntington, H. G. Corneil, and F . L.

Emert (Ind. Eng. Chem., 1938, 30, 86—91).—

Observations on the behaviour of air-kerosene and air-lubricating oil systems in a bubble-plate tower

(with a glass section) show th a t the pressure drop through th e plate is approx. cc the froth height. A plot of the observed head over the downspout against vol. of fluid entering is in good agreement with th a t calc, for 3 conditions of fluid head, the down­

spout o p e ra tin g :’ (1) a t low heads, as a weir; (2) a t interm ediate heads, as a free-running orifice taking a m ixture of froth and vapour, b u t w ith sufficient vortex area to allow free separation of the vapour from the liquid; (3) a t high heads, as an orifice running full, with capacity diminished by separation of vapour within the orifice. I. C. R.

A c tio n , in c ru s ta tio n , a n d p r e s s u r e lo ss in fra c tio n a tin g [c o lu m n ] p la te s . E. Kirsc h ba u m

(Z. Ver. deut. Ing., Beih. Verfahrenstech., 1937, 139—148).—Plates with various designs of bubble cap were investigated. The pressure drop per plate is reduced by increasing the area for vapour passage, thus increasing the load th a t th e column will handle.

Photographs of liquid currents in plates show th a t liquid on a modified plate is less mixed th an on a Kiihni plate. This less effective mixing results in a higher working efficiency. To prevent incrustation of the plates it is desirable to have large cross- sections rath er th an narrow openings. D ata for the distillation of E t0 H - H 20 when using various designs of plate are given. Pressure loss was independent of reflux ratio in bubble-cap plates, but not in mesh

plates. R. B. C.

A n a ly tic d e te r m in a tio n of p la te s in fr a c tio n ­ a tin g c o lu m n s. E. H. Sm oker (Trans. Amer. Inst.

Chem. Eng., 1938, 34, 165— 172).—An algebraic analysis is made of conditions in a fractionating column and a formula derived relating th e no. of theoretical plates required, the relative volatility of the components, the slope of the operating line, the mol. fractions of lower-boiling component in the liquid phase, etc. For distillation a t total reflux a simplified equation is given (cf. Underwood, B., 1933, 687).

Two worked examples are given showing the applic­

ation of the general formula. F . J . B.

V a p o ris a tio n p ro c e s s a n d b e a t tr a n s f e r in e v a p o ra to rs . D. St arck (Z. Ver. deut. Ing., Beih. Verfahrenstech., 1937, 175— 187).—H eat- transfer and pressure- and tem p-distribution d ata obtained for an evaporator, having an external, vertical, tubular heating element, when evaporating H 20 and aq. glycerin are given. Forced convection was obtained by injecting steam into the heating tube.

R. B. C.

A b s o rp tio n of g a se s in w e t cyclone s c r u b b e rs , H. F. Johnstone and R. V, Kl ein sch m id t (Trans.

Amer. Inst. Chem. Eng., 1938, 34, 181— 198).—Two wet cyclone dust washers were tested as absorption p lan t by adding sufficient Na2C 03 to th e spray-H20 to m aintain p a 5-5—8'0. The washers were 10-3 ft.

internal diam eter and 20-0 ft. high, and handled between them 25,000 and 55,000 cu. ft. of gas per min.

a t a tem p, of 500° F. and containing approx. 0-05%

of S 0 2. Owing to blockage of spray nozzles one of the washers was receiving only 50 gals, of liquor per min.

when th e other received 100 gals./min. The respec­

tive removals of S 0 2 were 85% and 95% and the corresponding average absorption coeffs. 1-58 and


Cl. I.—GENERAL; PLANT; MACHINERY. 859 4-05 lb.-mols./hr./cu. ft./atm . The results were

compared with a theoretical consideration of the absorption by spray droplets in cyclone scrubbers, and practical figures were shown by this to agree sufficiently closely w ith the experimental data of W hitm an and of H a tta on individual falling drops to justify the use of such theoretical treatm ent for general design purposes. F. J . B.

F lo w c o n d itio n s in cy clo n es. F. Wellm ann

(Feuerungstech., 1938, 26, 137—145).—The principles underlying the design of Van Tongeren dust separators are diagrammatically discussed. Descriptions of multi-aerodyne and cascade separators are given.

R. B. C.

F ilte r in g g a s th r o u g h g la s s [filte r fa b ric s].

W. H . Atk in so n (Chem. Met. Eng., 193S, 45, 176—

178).—Glass fabrics are unaffected by moisture, acidity, and temp, variation (within limits) and are therefore suitable filter media for gas. D. K. M.

W et d e d u s tin g [of b o ile r flue g a s e s ]. H.

Ham ann (Arch. W armewirts., 1938,19, 101—103).—

Recent developments in the design of the Honigmann wet deduster are diagrammatically described. The filter, which formerly comprised perforated plates of V2A steel, is now built up of hollow bricks, easily replaceable and filled w ith Raschig rings. D ata obtained when employing the improved apparatus to dedust boiler flue gases a t a German power station

are tabulated. R. B. C.

F lu e g a se s la u n d e re d to p re v e n t a i r p o llu tio n . R. V. Klein sch m id t (Power P lan t Eng., 1938, 42, 393—396).—Recent developments in th e removal of dust and S from boiler flue gases by the wet process

are reviewed. R. B. C.

F u n d a m e n ta ls of d r y in g a n d a i r co n d itio n in g . E. R. Gilliland (Ind. Eng. Chem., 1938, 30, 506 514).—A theoretical analysis of the mechanism of dry­

ing by evaporation leads to the conclusion th a t the mass-transfer coeffs. m ay be considered as analagous to the corresponding heat-transfer coeffs., and derived either by tho application of the surface-filin and turbulent-core concept or by empirical dimensional analysis. Application of such considerations to the prediction of wet-bulb temp, for various liquids is shown to give satisfactory agreement w ith experim ent­

ally determined vals. The method of attack suggested for wet-bulb calculations is also directly applicable to the const.-rate period of drying, b u t this is not tru e for th e falling-rate period. The falling-rato period starts when th e liquid content of the m aterial to be dried falls below a crit. val. which depends on the nature of th e m aterial and the ra te of drying. During the latter period the movement of liquid within the m aterial m ay be controlled by capillary forces rather th an by concn. differences, and insufficient experimental d a ta is available.

The modification of the moisture content of air in air-conditioning p lan t can also be analysed by com­

bining the mass- and heat-transfer coeffs. on the same basis as th a t used for the const.-rate drying period.

F . J . B.

D ry in g a ir a n d c o m m e rc ia l g a se s w ith ac tiv ­ a te d a lu m in a . R . B. Derr (Ind. Eng. Chem., 1938, 30, 384-—388).—D ata are given for the use of

activated A120 3 as an adsorbent for H aO. I t is claimed th a t air can be dried to <0-002 mg. of H 20 per 1., and th a t tho m aterial under normal conditions reaches saturation between 12 and 14%

of H 20 . The depth of bed required, the necessity for cooling it, and the temp, suitable for regeneration

.are discussed. F . J . B.

D e te rm in a tio n of th e d e n s itie s of g a s e s b y th e je t m e th o d . H . K. Le h r (Gas- u. W asser­

fach, 1938, 81, 434—437).—A modification of tho je t method (cf. B., 1936, 399) is described. The gas escapes through an aperture in the upper end of a cylindrical vessel surrounded by H 20 which flows in through another aperture in the widened base of the vessel. A t a particular in stant the pressure heads of influx of H aO (H ) and of efflux of gas (h) are noted and the usual expressions giving the rates of flow in term s of H and h aro equated : thence with the aid of an instrum ent const, the gas d can either be calc, or found from a nomogram. A. R. Pe.

P la n t c o n s tru c tio n a l m a te r ia ls in th e c h e m ic a l in d u s try . H. Argant (Tech. Ind. Chim., 1938, No.

277 bis, 147— 150). I. C. R.

P u m p s a n d g la n d s in c h e m ic a l in d u s tr y . V. Schille (Tech. Ind. Chim., 1938, No. 277 bis,

143—146). I . C . R .

S la g w oo l. F . W. Harr iso n (Fcuerungstech., 1938, 26, 150—154).—Its m anufacture, properties, and applications aro reviewed. R. B. C.

W a v e -rin g jo in t. W. R . D. Ma n n in g (Proc.

Chem. Eng. Group, Soc. Chem. Ind., 1937, 19, 110—

116).—A lecture, dealing w ith the development, advantages, limitations, and possibilities of this joint. Max. pressure for which it has so far been used successfully is given as 180,000 lb./sq. in.

A. K. G. T.

F ric tio n of a n o s c illa tin g b e a rin g . A. Fogg

and C. Jakem an (Dept. Sci. Ind. Res., Lubrication Res., Tech. P aper 3, 1938, 28 pp.).—The character­

istics of th e friction of an oscillating journal bearing under different conditions of load, tem p., and speed have been determined, and the effect of different lubricants on the friction is examined. The lubricating qualities of vegetable oils and of compounded oils were superior to those of mineral oils. H. C. M.

O p e ra tio n a l th e o ry of s o lid fric tio n . L. A.

Pip e s (Phil. Mag., 1938, [vii], 25, 950—961).—


F ir e p re v e n tio n a n d activ e a n d p a s s iv e defence a g a in s t fire in th e c h e m ic a l in d u s tr y . J . Cochois

(Tech. Ind. Chim., 1938, No. 277 bis, 200—209).—The causes of fires, dangerous operations and installations, and methods of fire prevention and fire fighting are discussed. An analysis of the causes of over 2000 fires reported in Paris during 1936 is included.

I. C. R.

L a te st d e v e lo p m e n ts in th e d e te c tio n of fire s.

E. Re chner and A . An t o n i (Compt. rend. X V II Cong. Chim. Ind., 1937, 548—557).—The typ e of equipment for the autom atic control of fires depends on the combustible m aterial involved and especially on the products of distillation etc., in th e period before ignition starts. Detectors are in use which


depend on the rate of rise of tem p., th e abs. tem p., or the production of smoke. The “ radio-electric ” detector depends on the ratio of the electrical con­

ductivity of a stream of air contam inated w ith traces of H 2, C 02, etc. and a stream of fresh air, when both have" been ionised by R a emanations, thus making it possible to detect those stages of precombustion distillation which yield no visible smoke. E. J . B.

G a s-fire d fu rn a c e s . C a lo rim e try . D e te rm in ­ in g d ew p o in t of g a s e s u n d e r p r e s s u r e . D e te r­

m in in g coeff. of fric tio n .—See II. D e te rm in in g H 2S 0 4 a n d S 0 2 i n flue g a s e s . S 0 2 f r o m w a s te g a s e s .—See V II. C h a m o tte b ric k s fo r b o ile r fu rn a c e s. S u rfa c e p r o p e rtie s of v isc o u s liq u id s .

—See V III. P o w e r p r e s s e s .—SeeX . R o lle r m ills fo r p a in t, a n d p a in t-g rin d in g p ro b le m s . F u m e c o n tro l fo r v a r n is h p la n t.—See X III. A u to m a tic d iffu s e r.—Seo X V II. U se of coffee b y -p ro d u c ts .

—See X IX .

See also A., I, 352, [M e a s u re m e n t of] h a r d n e s s . 371, T h e r m o - re g u la to r s . 372, R efe ren c e ta b le s fo r F e - a n d C u -c o n s ta n ta n th e rm o c o u p le s .

Pa t e n t s.

R o ta ry m u ffle fu rn a c e s. Meta llg es. A.-G.

(B.P. 484,358, 11.5.37. Ger., 10.6.36).—Resilient supports for the muffle tube are described, the springs being outside the shell. B. M. V.

C o n tin u o u s h e a tin g fu rn a c e s. T. Sta ssin e t

(B.P. 485,348, 14.7.37. Ger., 11.8.36).—A pusher furnaco for ingots or the like is divided into heating and soaking zones, the roof descending between the zones to afford only a narrow passage and being formed w ith transverse grooves to form a kind of labyrynth packing, the Reynolds no. for the flow of gases in tho passage being 1800—5000 (2200).

B. M. V.

F u rn a c e s . F. W. Es k e and C. A. Sc h eper s

(B.P. 482,221, 30.10.36. Addn. to B .P. 469,799;

B., 1938, 23).—In apparatus generally as described in the prior patent, when the H 20 tem p, is < a desired min. an electric fan is started which draws the smoko gases (and flue gases if desired), mixes them with air, and injects them under the fire-grate, the proportion of th e gases being variable by means of dampers. W hen the H 20 tem p, reaches a max.

the fan is stopped and the chimney draught will eventually take charge and cause the conduits through the fan to become secondary air inlets, the air having been preheated in the ashpit.

B. M. V.

B la s t-h e a tin g in s ta lla tio n s fo r b l a s t fu rn a c e s o r tb e lik e . A.-G. Br o w n, Boveri & Co. (B .P . 484,145, 2.12.37. Ger., 2.12.36).—The heating is regenerative, the Cowper heating being accelerated by th e use of pressures > 1 atm . (1-25 atm .) both for combustion and a h heating. Tho speed of the gases is > 4 0 m./sec., and th e pressure provided by a gas turbine and compresser, the exhaust gases of the turbine being used to preheat the Cowper gas and ah .

B. M. V.

H e a t-e x c h a n g e a p p a r a tu s . J . H . Hoffm a n, Assr. to G. Po ly siusA.-G. (U.S.P. 2,073,105, 9.3.37.

Appl., 26.11.35).—Preheating and nodulising of

pulverulent feed m aterial by means of hot gases is effected a t the upper end of a ro tary kiln by apparatus including a bowl-shaped centrifuge rotating about a vertical a x is ; a somewhat similar apparatus is utilised to cool the clinker a t the other end of the kiln, by means of cold air, w ith sufficient rapidity to

effect quenching. B. M. V.

H e a t-a b s o rb in g o r h e a t-e x c h a n g in g a p p a r a tu s . Ak t ie b. Ro senblads Pat e n t e r (B .P . 484,635, 21.5.37. Swed., 22.5.36).—Countercurrent, direct contact of liquid and gas or vapour is effected in an apparatus comprising a no. of co-axial, cylindrical or truncated-conical walls irrigated with the liquid, the walls being plain, corrugated, or formed of whe

mesh. B. M. V.

P la te b e a t-e x c h a n g e a p p a r a tu s fo r flu id s . E. Morterud (B.P. 484,551, 18.9.37. Norw., 20.10.36 and 9.8.37).—A device for feeding heating steam into a no. of flat, hollow plates is described;

all the joints are held tig h t by a single spring.

B. Mi V.

P la te a p p a r a tu s f o r in te rc h a n g e of h e a t b e tw e e n flu id s. Ch er r y- Bu r r e l lCo rp., Assees. of C. B . Dalzell (B .P . 485,241, 24.5.37. U.S., 27.1.37).

—I n a filter-press type of exchanger the plates are embossed so th a t the bosses m ating in staggered relation form tortuous passages for th e fluids.

B. M. V.

H e a t-in s u la tin g m a te r ia l. G. A. Bole, Assr.

to Laclede Ch r isty Cl a y Products Co. (U .S .P . 2,073,138, 9.3.37. Appl., 9.8.30).—A m ixture of 48—80-mesh raw cyanite with a smaller proportion of clay and, if deshed, plaster of Paris and dolomite is pasted w ith dil. H oS 0 4, cast, dried, and fired at

1260—1425°. “ B . M. V.

M a n u fa c tu re of ja c k e te d p a n s . Thom pson Bro s. (Bilsto n), Lt d., and H. J . Thompson (B.P.

484,337, 25.1.37).—Tho construction of the top rim and closure, providing a smooth inner surface, is

described. B . M. V.

G a s-h e a te d b o ilin g p a n s , b o ile rs , u te n s ils , a n d tb e lik e . D . Ch a n d l e r, J . H . Ba r r alet, and South Metropolitan Gas Co. (B.P. 484,718, 13.11.36).—Pressed between the pan and th e re ­ fractory setting are coils of metallic whe, which extract heat from the flue gases and heat th e pan by

conduction. B. M. V.

M e a s u re m e n t of te m p e r a tu r e . Cam br id g e In­ str um ent Co., Lt d., and E . B. Moss (B.P. 483,312, 15.10.36).—A radiation-type pyrom eter, in which the hot body (e.g., an article travelling on a conveyor) is viewed for > 1 sec. through a hand-operated shutter and for which the galvanometer is of the type th a t will record to tal energy received, is described.

B. M. V.

T h e r m o m e te rs . H . Sie be r t (B.P. 484,256, 11.6.37).—A box-like -protector is made enthely of artificial resin; the capillary tube and scale plate

are removable. B. M. V.

B im e ta llic th e r m o s ta tic e le m e n ts . H . A . Wil­ sonCo., Assees. of R . G. Waltem berg (B.P. 484,946, 1.5.37. U.S., 16.5.36).—F or the low-expansion element a known alloy of Fe w ith 35— 42% of Ni




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