- Email: [email protected]
Properties and testing of magnetic materials
\ p r . . ~,~2S.l
l~ooK
],,l,.\ IE\\ . .
58()
by the issue of this volume a labor-saxing work of great value. Within its covers will be found a resum¢~ of all the important studies which have been made in modern times on thermionic emission. The work is most thoroughly documented from English and American and French and (;erman sources. Most notable among these is the work by O. W. Richardson, " T h e Emission of Electricity from Hot Bodies" the latest edition of which appeared in I92 r. The excellent rendition into English by Professor Clarke is a worthy setting ior a book of timely value. [A:CIEN E. PICOI,I,71', PROPERTIES AND TESTING OF MAGNETIC MATERIALS. By Thomas Spooner, Research Engineer, "Westinghouse Electric and Manufacturing Company; Chairman of the Magnetic Properties Committee of the American Society for Testing Materials; Member American Institute of Electrical Engineers; Member American Physical Society. xiv-385 pages, 23 x 15 cm., cloth. New York, McGraw-Hill Book Company, Inc., 1927. Price, $5APPHEI) MAGNETISMS. By T. F. Wall, D.Sc., D.Eng., M.I.E.E., A.M. Inst. C.E.' l lead of the Electrical Engineering Department, University of Sheffield. 262 pages, 25 x I8 cm., cloth. New York, D. Van Nostrand Company, Inc., ~927 . Price, 88. Research workers must ever rely upon periodical literature for information on the subject of their investigation for it is only from such sources that recent enough data; and in its original form may be found, but there are many more users of scientific literature, whose needs are less critical, to whom such literature is not available. For them, a well-arranged text-book containing recent data often is a more efficient source of information, and either new books or revised editions of oht ones must appear at reasonable intervals. The appearance of the two works before us is in harmony with these circumstances. The first mentioned deals specifically with the properties and testing of magnetic materials; the second is more of a general treatise in its scope, and both contain recent information. Mr. Spooner's work is devoted chiefly to a consideration of the lnagnetic properties of commercial ferro-magnetic materials and to a description and discussion of the various useful methods of test suitable for conunercial inspection and for research. Only a brief outline of the relations of the quantities of the magnetic circuit is given, a knowledge of these fundamentals being assumed. In the tirst of the three divisions of the work which occupies one-half the volume a review is made of the quantities represented by magnetization and permeability curves; then, proceeding to normal hysteresis and eddy-current losses, range of permeability and core-loss values for w~rious irons and their alloys are analyzed at length. A short description of some non-magnetic ferrous alloys is included. The chapter on permanent magnet steels, their composition, treatment and pruperties, adds materially to the gradually accumulating collection of rational information on the " t r a d e secrets" of this art. Then follow chapters on hysteresis under special conditions and effects of frequency on apparent permeability aud iron losses. The effects of direction of grain and mechanical stress on magnetic properties, under which are included the effects of rolling and punching and shearing of sheet nmterial, are given a chapter of considerable length. The phenomenon of magnetostriction is accorded a brief account only as having little bearing in its present
59 °
Book REwEws.
[J. F. I.
development on commercial applications. Other "effects," it may be noted, i m p o r t a n t as they are in their relation to atomic theory, are also ignored for a like reason. The important factor of annealing electrical sheet and the heattreating of permanent-magnet steels is given space in keeping with its importance. Another chapter deals with reversible t e m p e r a t u r e effects as distinguished from the permanent temperature effects of the previous chapter. Chapters on alternating magnetizing current and on the mechanical properties and thermal conductivity of electrical sheet complete the first part of the work. The second part constitutes a treatise on commercial magnetic testing a n d is distinctive in laying stress upon commercially applicable methods and apparatus. This part of the subject is sub-divided into the two main divisions of direct-current testing and alternating-current testing. Under the former division are considered numerous methods and lay-out of apparatus for the measurement of induction and magnetizing force and, under the latter, those applicable to the determination of losses under alternating-current flux. A chapter on core-losses in transformers and in rotating machines, and on magnetic analysis, constitutes the third part. The latter is on the promising system of testing the physical condition and properties of materials from their magnetic qualities. The work is thoroughly documented by references to original sources at the end of each chapter which relate to the topics there discussed. The volume contains an immense amount of thoroughly analyzed and carefully appraised applicable data in irreproachable typographical setting. Professor Wall's work deals with principles as well as with application. In a first part of this work, the principles of applied magnetism are considered; in the second part, magnetic testing. Under Part I are developed first the usual formulas connecting the quantities which express the phenomena of magnetic induction and an account of the molecular theory of magnetism. Proceeding to application, there is fully discussed in the second chapter t h e theory of permanent magnets. In addition to the analytical deductions of this chapter many matters of practical interest are included. The third chapter covers a collection of metallurgical facts of unusual interest and their relationship to the magnetic properties of iron and steel and the fourth some characteristics of magnetic substances. In the latter are some very interesting data on permanent magnet steels, on the now wellknown and much appreciated " p e r m a l l o y " and the recent Ferranti non-magnetic cast iron. The fifth chapter contains an analytical and experimental account of reluctivity and the Fr6hlich-Kennelly relationship. Magnetostriction which has received much attention from recent investigators is given the sixth chapter. The discovery of the electron and the development of the electron theory of matter which has placed the ioo-year-old AmpSre theory of magnetism on a firm foundation of experimental fact is considered in the seventh chapter. With view to testing the possible change of the magnetic properties due to a change of electronic orbits under an intense magnetic field, a full account is given in chapter eight of the author's method and apparatus for producing a field of the order of 5o0,00o gausses by means of condenser discharge. Under part two, various methods of magnetic testing are considered. In this are included the ballistic galvanometer, the fluxmeter, determination of magnetization curve and hysteresis loop; bar-and-yoke method; magnetization curve and hysteresis loop by magnetometer method ; total losses in iron laminations; measure-
.'\l,r., ~,)28 l
BOOK I~F.VtEWS.
591
ment by means of the magnetic square; separation of the losses; hysteresis loop for transformer cores by Scott's method. In the last chapter are discussed the testing of pernlanent magnets; testing of feebly magnetic substances and testing for mechanical and other defects in steel by magnetic methods, a mode of testing which the author states is giving promise of great practical value. The work is set up in somewhat larger type than is usual in works of this sort and the text is correspondingly comfortable to read; that feature necessarily increases the size of the volume. The subject is presented with great clarity and in its modern aspects. LUCIEN E. PICOLET. PYROXYLIN ENAMELS AND LACQUERS, THEIR RAW MATERIALS, MANUFACTURE AND APPLICATION. By Samuel P. Wilson, M.A., Ph.D. Second edition, enlarged, xv-253 pages, illustrations, 8vo. New York, D. Van Nostrand Conapany, Inc., 1927. Price, $3.5 o. The soluble cottons obtained by nitrating the natural form have been known for nlany years. For a long while their principal use was for explosives. In this use they produced very profound modifications in the art of war but did not get the application for engineering purposes that the corresponding derivatives from glycerol and the phenolic bodies have obtained. From an early period, however, in the history of pyroxylins, their solubility in some familiar liquids led to their use as coatings of various kinds. Many years ago the so-called wet process of photography was invented, based on the use of a solution of nitrated cotton in a mixture of alcohol and ether which, allowed to evaporate, gave a very satisfactory coating on the glass plate as a carrier for the sensitive emulsion. It is necessary also to note the very important product celluloid which has found so many applications, especially as a substitute for bone and ivory. The applications of these cotton products through the productions of varnishes and enamels have greatly extended their usefulness and manufacture. The present work is a stunmary of the technology of this subject and begins by describing the manufacture of the nitrated nlaterial and a description of its properties; then a large amount of space is devoted to the solvents which are quite numerous and are grouped a,,: alcohols, esters and ketones; also a number of liquids which are not solvents are included in these descriptions. It is to be regretted that the coal tar products of the closed chain type are referred to as benzol, toluol and xylol instead of with their proper termination " e n e , " but it seems hard to drive out of the practical worker these erroneous methods of expression. The plasticisers and the many accessory substances which are added to the solutions in order to adapt them to a variety of uses are described in detail. Part 2 is devoted to bronzing liquids and to those applications which are called by the curious name of "dopes." The work concludes with a description of a variety of analytic methods, including some suggestions for avoiding the hazards attending the use of such materials. The work contains therefore a very large amount of information of a practical character on a line of industry which is of comparatively recent development and of widespread application. 1tENP.Y LEFFMANN.
l~ooK
],,l,.\ IE\\ . .
58()
by the issue of this volume a labor-saxing work of great value. Within its covers will be found a resum¢~ of all the important studies which have been made in modern times on thermionic emission. The work is most thoroughly documented from English and American and French and (;erman sources. Most notable among these is the work by O. W. Richardson, " T h e Emission of Electricity from Hot Bodies" the latest edition of which appeared in I92 r. The excellent rendition into English by Professor Clarke is a worthy setting ior a book of timely value. [A:CIEN E. PICOI,I,71', PROPERTIES AND TESTING OF MAGNETIC MATERIALS. By Thomas Spooner, Research Engineer, "Westinghouse Electric and Manufacturing Company; Chairman of the Magnetic Properties Committee of the American Society for Testing Materials; Member American Institute of Electrical Engineers; Member American Physical Society. xiv-385 pages, 23 x 15 cm., cloth. New York, McGraw-Hill Book Company, Inc., 1927. Price, $5APPHEI) MAGNETISMS. By T. F. Wall, D.Sc., D.Eng., M.I.E.E., A.M. Inst. C.E.' l lead of the Electrical Engineering Department, University of Sheffield. 262 pages, 25 x I8 cm., cloth. New York, D. Van Nostrand Company, Inc., ~927 . Price, 88. Research workers must ever rely upon periodical literature for information on the subject of their investigation for it is only from such sources that recent enough data; and in its original form may be found, but there are many more users of scientific literature, whose needs are less critical, to whom such literature is not available. For them, a well-arranged text-book containing recent data often is a more efficient source of information, and either new books or revised editions of oht ones must appear at reasonable intervals. The appearance of the two works before us is in harmony with these circumstances. The first mentioned deals specifically with the properties and testing of magnetic materials; the second is more of a general treatise in its scope, and both contain recent information. Mr. Spooner's work is devoted chiefly to a consideration of the lnagnetic properties of commercial ferro-magnetic materials and to a description and discussion of the various useful methods of test suitable for conunercial inspection and for research. Only a brief outline of the relations of the quantities of the magnetic circuit is given, a knowledge of these fundamentals being assumed. In the tirst of the three divisions of the work which occupies one-half the volume a review is made of the quantities represented by magnetization and permeability curves; then, proceeding to normal hysteresis and eddy-current losses, range of permeability and core-loss values for w~rious irons and their alloys are analyzed at length. A short description of some non-magnetic ferrous alloys is included. The chapter on permanent magnet steels, their composition, treatment and pruperties, adds materially to the gradually accumulating collection of rational information on the " t r a d e secrets" of this art. Then follow chapters on hysteresis under special conditions and effects of frequency on apparent permeability aud iron losses. The effects of direction of grain and mechanical stress on magnetic properties, under which are included the effects of rolling and punching and shearing of sheet nmterial, are given a chapter of considerable length. The phenomenon of magnetostriction is accorded a brief account only as having little bearing in its present
59 °
Book REwEws.
[J. F. I.
development on commercial applications. Other "effects," it may be noted, i m p o r t a n t as they are in their relation to atomic theory, are also ignored for a like reason. The important factor of annealing electrical sheet and the heattreating of permanent-magnet steels is given space in keeping with its importance. Another chapter deals with reversible t e m p e r a t u r e effects as distinguished from the permanent temperature effects of the previous chapter. Chapters on alternating magnetizing current and on the mechanical properties and thermal conductivity of electrical sheet complete the first part of the work. The second part constitutes a treatise on commercial magnetic testing a n d is distinctive in laying stress upon commercially applicable methods and apparatus. This part of the subject is sub-divided into the two main divisions of direct-current testing and alternating-current testing. Under the former division are considered numerous methods and lay-out of apparatus for the measurement of induction and magnetizing force and, under the latter, those applicable to the determination of losses under alternating-current flux. A chapter on core-losses in transformers and in rotating machines, and on magnetic analysis, constitutes the third part. The latter is on the promising system of testing the physical condition and properties of materials from their magnetic qualities. The work is thoroughly documented by references to original sources at the end of each chapter which relate to the topics there discussed. The volume contains an immense amount of thoroughly analyzed and carefully appraised applicable data in irreproachable typographical setting. Professor Wall's work deals with principles as well as with application. In a first part of this work, the principles of applied magnetism are considered; in the second part, magnetic testing. Under Part I are developed first the usual formulas connecting the quantities which express the phenomena of magnetic induction and an account of the molecular theory of magnetism. Proceeding to application, there is fully discussed in the second chapter t h e theory of permanent magnets. In addition to the analytical deductions of this chapter many matters of practical interest are included. The third chapter covers a collection of metallurgical facts of unusual interest and their relationship to the magnetic properties of iron and steel and the fourth some characteristics of magnetic substances. In the latter are some very interesting data on permanent magnet steels, on the now wellknown and much appreciated " p e r m a l l o y " and the recent Ferranti non-magnetic cast iron. The fifth chapter contains an analytical and experimental account of reluctivity and the Fr6hlich-Kennelly relationship. Magnetostriction which has received much attention from recent investigators is given the sixth chapter. The discovery of the electron and the development of the electron theory of matter which has placed the ioo-year-old AmpSre theory of magnetism on a firm foundation of experimental fact is considered in the seventh chapter. With view to testing the possible change of the magnetic properties due to a change of electronic orbits under an intense magnetic field, a full account is given in chapter eight of the author's method and apparatus for producing a field of the order of 5o0,00o gausses by means of condenser discharge. Under part two, various methods of magnetic testing are considered. In this are included the ballistic galvanometer, the fluxmeter, determination of magnetization curve and hysteresis loop; bar-and-yoke method; magnetization curve and hysteresis loop by magnetometer method ; total losses in iron laminations; measure-
.'\l,r., ~,)28 l
BOOK I~F.VtEWS.
591
ment by means of the magnetic square; separation of the losses; hysteresis loop for transformer cores by Scott's method. In the last chapter are discussed the testing of pernlanent magnets; testing of feebly magnetic substances and testing for mechanical and other defects in steel by magnetic methods, a mode of testing which the author states is giving promise of great practical value. The work is set up in somewhat larger type than is usual in works of this sort and the text is correspondingly comfortable to read; that feature necessarily increases the size of the volume. The subject is presented with great clarity and in its modern aspects. LUCIEN E. PICOLET. PYROXYLIN ENAMELS AND LACQUERS, THEIR RAW MATERIALS, MANUFACTURE AND APPLICATION. By Samuel P. Wilson, M.A., Ph.D. Second edition, enlarged, xv-253 pages, illustrations, 8vo. New York, D. Van Nostrand Conapany, Inc., 1927. Price, $3.5 o. The soluble cottons obtained by nitrating the natural form have been known for nlany years. For a long while their principal use was for explosives. In this use they produced very profound modifications in the art of war but did not get the application for engineering purposes that the corresponding derivatives from glycerol and the phenolic bodies have obtained. From an early period, however, in the history of pyroxylins, their solubility in some familiar liquids led to their use as coatings of various kinds. Many years ago the so-called wet process of photography was invented, based on the use of a solution of nitrated cotton in a mixture of alcohol and ether which, allowed to evaporate, gave a very satisfactory coating on the glass plate as a carrier for the sensitive emulsion. It is necessary also to note the very important product celluloid which has found so many applications, especially as a substitute for bone and ivory. The applications of these cotton products through the productions of varnishes and enamels have greatly extended their usefulness and manufacture. The present work is a stunmary of the technology of this subject and begins by describing the manufacture of the nitrated nlaterial and a description of its properties; then a large amount of space is devoted to the solvents which are quite numerous and are grouped a,,: alcohols, esters and ketones; also a number of liquids which are not solvents are included in these descriptions. It is to be regretted that the coal tar products of the closed chain type are referred to as benzol, toluol and xylol instead of with their proper termination " e n e , " but it seems hard to drive out of the practical worker these erroneous methods of expression. The plasticisers and the many accessory substances which are added to the solutions in order to adapt them to a variety of uses are described in detail. Part 2 is devoted to bronzing liquids and to those applications which are called by the curious name of "dopes." The work concludes with a description of a variety of analytic methods, including some suggestions for avoiding the hazards attending the use of such materials. The work contains therefore a very large amount of information of a practical character on a line of industry which is of comparatively recent development and of widespread application. 1tENP.Y LEFFMANN.