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Aluminium-Magnesium AlloysAuthor(s): R. H. ThurstonSource: Science, New Series, Vol. 11, No. 281 (May 18, 1900), pp. 783-785Published by: American Association for the Advancement of ScienceStable URL: http://www.jstor.org/stable/1626342 .Accessed: 28/10/2014 04:34

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MAY18, 1900.] SCIENCE. 783

ALUMINIUM-MAGNESIUM ALLOYS.

THERE have recently appeared accountsof a ' newlv discovered ' series of alloys ofaluminium and magnesium which are con-sidered by their discoverers peculiarly val-

able and promising. Dr. Mach, for ex-ample, has named such alloys ' magnalium.'Possibly other investigators may not beaware that this series was long ago investi-gated at the suggestion of the writer and inconsiderable detail in the laboratories ofSibley College. The writer published anaccount of the work in 1893 and it has beenreproduced or summarized in several casessince.* The following are the tabulatedresults of such tests of strength of the twometals and their alloys as then determined.The succeeding graphic illustration of their

variation of quality and the law of suchvariation is from a paper read by ProfessorCarpenter, in 1898, before the AmericanSociety of Mechanical Engineers and ptub-lished in their transactions for that year.

From this table it will be seen that, formagnesium, the

Average breaking strength is 22,250 lbs. per sq. in.Average elastic limit is ........ 8,870Average elongation is .......... 2.8 per cent.Aveiuge modulus of elas-

ticity is ..................... 1,945,000

It is noticeable that though the densityof the metal is only two-thirds that ofaluminium it has one-half more tensile

strength; the latter averaging, pure, about15,000 pounds.The addition of magnesium to aluminium

reduced ductility steadily with rising pro-portions and, at one-third magnesium andtwo-thirds aluminium, the alloy was asbrittle as glass. Magnesium refused toalloy with iron. The alloys with alumin-ium, where the proportion of magnesiumis small, give promise of finding useful andvaluable applications in the arts.

The series of tests of which the diagram

TENACITY OF MAGNESIUM.

Number of Test Diameter. Breaking Breaking Load Elastic Limit Extension Modulus ofPiece. Load Lbs. Lbs. per sq. in. Lbs. per sq. in. per cent. Electricity.

1 ...... ........ .433 3,500 23,800 8,800 4 2 2,040.0002 ............. .433 3,250 22,050 ........ 1,860,0003 .......................... .442 3,200 20,900 10,780 1.8 2,060,0004.......................... .435 2,900 19.500 8,400 2.5 1,830,0005 ............. .424 3,500 24,800 7,090 3.1 1,930,0006. .432 3,300 22,500 ......... 2.3 ............

ALLOYS OF ALUMINIUM AND MAGNESIUM.

Number of Percentage of Specific Gravity Breaking Strength. Elastic Limit. Modulus ofTest Piece. Magnesium. . lbs. per sq in. lbs. per sq. in. Elasticity.

1 0 2.67 13,685 4,900 1,690,0002 2 2.62 15,440 8,700 2,650,0003 5 2.59 17,850 13,090 2,917,0004 10 2.55 19,680 14,600 2,650,0005 30 2.29 5,000 ......... ............

* For earlier work on properties of magnesium andits alloys, see 'Materials of Aeronautic Engineering, 'Transactions Aeronautic Congress, Chicago, 1893; alsoSibley Journal, April, 1894.-R. H. T.

' Magnesium as a Constructive Material. '-R. H. T.London Machinery, May, 1896; 'Industries and Iron,'May 22, 1896. Also Thurston's 'Materials of Engi-neering,' vol. iii., pp. 94-561.

'Mechanical Properties of certain Aluminium Al-loys,' R. C. Carpenter ; Trans. A. S. M. E., vol. xix.,1898, No. DCCLXXXI V.

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784 SCIENCE. [N. S. VOL. XI. No. 281.

is the record in graphical form were madein 1893 by Messrs. Marks and Barracloughin the course of regular graduate work in

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ALUMINIUM AND MAGNESIUM.

92SW lI% If, 2 a. _V

228 1 2 e 4 v C 7 8 9 to 28 12 13 14 16

the mechanical laboratories of Sibley Col-lege.* The writer had always anticipateduseful employment of such alloys, since theproperties of magnesium became familiarto him, in the experimental use of themetal for signal purposes in army andnavy, 'in the sixties,' with the assistanceof Admiral Luce and of General Myer,then Chief Signal Officer of the Army ofthe United States.

The volatility and combustibility of thelighter metal are elements of difficulty in itsuse in alloys, especially with those, ascopper, which have a high temperature offusion; but a little care and sometimesvery simple special precautions will befound to readily evade such obstructions toits use.t The metal, weighing about two-

thirds as much as aluminium and betweenone-fourth and one-fifth as much as ironor steel, has a more than proportional

strength, and pieces of the metals havingsimilar size will carry more nearly equalloads. The first at all complete studies ofthe constructive value of this metal and itsalloys were made, on the initiative of thewriter, as above, in the laboratories of Sib-ley College' to which laboratories he hadturned over his collected material for thatpurpose, mainly, at the time, with a viewto securing some definite knowledge of itsvalue for the

purposes of'aeronautic en-gineering,' and with the intention, actually

carried into effect, of reporting the outcometo the International Engineering Congressat Chicago in 1893. The result was to showthat aluminium might be considerablystrengthened by alloying with magnesium insmall quantities as above; but that the al-loying metal was itself stronger than the al-loys, and that the presence of aluminiumreduced the strength of magnesium.

The best comparison of these metals andtheir alloys is that by comparing the lengthsof bars of the metal, suspended from oneend, that can be carried without breaking.The extreme range of the tenacities ofmagnesium was between 20,000 and 30,000pounds per square inch, corresponding to a

* Mr. Marks is now Assistant Professor of Mechan-ical Engineering at Harvard University and Mr.Barracough has charge of the Department of Electrical

Engineering at the University of Sidney, N. S. W.,of which institution he is an alumnus. Mr. Marksis a graduate of the University of London and ofMason College, Birmingham, England.

t The writer employed magnesium for illuminatingand for signal purposes about the close of the civilwar (1864-65), and, while stationed at the U. S.Naval Academy (1865-71) experimented with a va-riety of signal apparatus devised by himself for long-distance work, as above. The most successful formsof apparatus for this application of the metal wereconstructed for the use of magnesium in powder, inwhich a suitable proportion of sand was used to in-

sure free flow as well as economy. The most success-

ful form for other illumination, as photography, sta-tionary signal lamps, theater tableau work, etc., wasthe ribbon lamp, of which latter a large number were

in use when the electric light entered the field andthrew them out. See 'A New Marine Signal Light, 'describing this apparatus (patented in May, 1866),Journal Franklin Institute, 1867, R. HI. Thurston, inwhich paper the writer gives the costs of signalling:sixty cents by the magnesium apparatus employed byhim, and six dollars for the same message sent by thethen usual Coston signals. The marine apparatuswas taken by Admiral Luce on his cruise to the Med-iterranean in the summer of 1366, and the army sig-nal was employed by General Myer about Washing-ton. The latter is now in the possession of thewriter. It was built from the designs of the writer by

the American Magnesium Co. of Boston.

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MAY 18, 1900.] SCIENC2. 785

suspension of 30,000 to 40,000 feet. Thisis the equivalent of steel of about 100,000

pounds tenacity. Could the cast portionsof the steam-engine be made in this ma-terial for our torpedo-boats or aeronauticand automobile machinery their weightswould be reduced about one-half. It re-mains to be seen whether, the costs permit-ting, this change would be to any extentpracticable. Dynamos have been construc-ted, in the shops of Sibley College, of alu-minium and a gain thus secured for portableand automobile work of some importance,and it is possible that magnesium, with itshigher tenacity and greater lightness, mayprove the coming material for some suchwork. Costs will undoubtedly fall rapidlywith increasing area of market.

R. H. THURSTON.

SCIENTIFIC BOOKS.

La constitution du monde. By MADAME CL1PM-ENCE ROYER. Published by SchleicherFreres, 15 Rue des Saints-PNres, Paris. Con-taining 799 pages, 100 chapters, 92 figures,and 4 plates.This pretentious volume is claimed by its

author to contain a new and satisfactory philos-ophy of nature including everything from thegeometrical structure of molecules to a theoryof the evolution of worlds. In a somewhat re-markable preface the author expresses in forci-ble terms her contempt for those philosopherswho maintain that certain things are unknow-

able, and asserts that their speculations wereadvanced to enslave the minds of men andsupport the dogmas of theologians. The fol-lowing quotations of remarks concerning scien-tific subjects will indicate her attitude of mind:

The kinetic theory of gases is certainly aromance conceived by the imagination of aGerman mathematician. The non-euclidiangeometries founded on sophistic generaliza-tions of analysis * * * have for their resultand their end, the clouding of the intellect inundermining the foundations of rational certi-tude, to the profit of those who are attempting

to reduce mankind * * * to the credo quia ab-surdum of blind and unquestioning faith.

The ideas advanced upon scientific questionsare not worth the space that it would requireto enumerate them, much less to make anycritical comments. They indicate, as is inreality confessed in the preface, that the authorhas read, though widely, with a mind stronglybiased by preconceived notions, and they showat every point a lamentable lack of scientifictraining and spirit. The contents of the 99thchapter are sufficient to illustrate the statement.The author in her ' evolution du monde ' sup-poses that at some remote time a planet from

exterior space struck Saturn a glancing blowgreatly accelerating its rotation; that the Satur-nian oceans and portions of the solid crust werehurled off and formed the rings, which are ice,or perhaps aluminium; that the striking planetwas broken up forming the satellites of Saturn,Jupiter, Uranus, Neptune, Mars, and the Moon,the asteroids, the meteor streams; that Venusand Mercury have no satellites because theywere on the opposite side of the sun when thecollision occurred; that the Moon and the satel-lites of Mars move with less linear velocity thanthose of the larger planets because they are sofar from Saturn that the velocities of the flyingfragments had largely died out before theyreached their respective primaries; and thatthe second satellite of Mars ' by a remarkableexception does not fulfill the laws of Kepler.'The figure inserted in the chapter makes thetheory very clear.

It is to be regretted, for the sake of theauthor who devoted so much time to writingthe book, and for the sake of Madame Valen-

tine Barrier who bore the expense of its publi-cation, that it is impossible to say that thework is worth reading. F. R. M.

The Chemistry of Soils and Fertilizers. ByHARRY SNYDER, B.S., Professor of Agricul-tural Chemistry, University of Minnesota,and Chemist of the Minnesota AgriculturalExperimental Station, Easton, Pa. TheChemical Publishing Company. 1899. 12mo.ix + 277 pp. Price, $1.50.This book is the outgrowth of courses of in-

struction given at the University of Minnesota

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