110 



SCIENCE. 



FN. S. Vol. VIII. No. 186. 



the limits to which he has confined himself. 

 One will find in this work a strong appreciation 

 of the remarkable papers of Oliver Heavyside 

 and valuable chapters on the Elements of Hy- 

 drodynamics. Teachers will highly appreciate 

 the introduction of such chapters in a work on 

 electricity, for one of the principal difficulties 

 in reading Maxwell's book arises from his ob- 

 scure use of hydrodynamical equations. In- 

 deed, I am tempted to regard this portion of 

 Professor Gray's book as the most valuable to 

 the student, leading him to see the importance 

 in the modern treatment of electrical theories, 

 of hydrodynamics, and compelling him to grap- 

 ple with Lamb's classical work on this subject. 



The author has embodied without essential 

 change Hertz's mathematical discussion of 

 electric waves, and further discussion of this 

 subject is promised in the second volume. We, 

 therefore, canuot venture to criticise his treat- 

 ment of this subject. It is evident that he 

 intends his treatment of this growing sub- 

 ject to be a full one, for the first volume 

 before us contains Lorentz's remarkable the- 

 oretical prediction of Zeeman's discovery of 

 the doubling and tripling of spectral lines 

 in the magnetic field. We know of no other 

 text-book at present which has incorporated 

 the work of Lorentz, or one which contains 

 such a well digested account of the funda- 

 mental equations of the electrodynamical the- 

 ory of light. We confess to a certain feeling 

 of disappointment at the author's treatment of 

 electrostatics and of the vexed subject of dis- 

 placement currents ; perhaps in the imperfect 

 state of our knowledge no better or fuller treat- 

 ment is possible. Possibly the second volume 

 will contain an analysis of Professor J. J. 

 Thomson's theory of polarization and tube of 

 force, and of Helmholtz's theory of ions. 



The author has selected fundamental experi- 

 ments with care, and the practical electrician 

 will find much apart from the mathematical 

 treatment which will interest him, notably a 

 full account of Lord Kelvin's mariner's com- 

 pass. A young electrical engineer who studied 

 Maxwell's treatise with me ten years ago told 

 me that when he first entered into the employ- 

 ment of a great electrical firm he Avas afraid 

 to leave his copy of Maxwell where it might be 



seen, for fear that he would be considered a man 

 in the clouds, unfitted by the study of mathe- 

 matical theories to cope with practical prob- 

 lems of electricity. He now, however, leaves 

 his copy boldly on his desk and in the work- 

 shop. Such has been the advance in the study 

 of electricity among the new schools of electri- 

 cians. And probably a copy of Professor Gray's 

 treatise will be seen in the workshop along 

 side that of Maxwell. j^^^^ Trowbridge. 



Bevieiv and Bibliography of the Metallic Carbides. 

 By J. A. Mathews. Smithsonian Miscel- 

 laneous Collections, 1090. City of Washing- 

 ton, 1898. 8vo. Pp. 32. 

 The Chemical Section of the American As- 

 sociation for the Advancement of Science in 

 1882 appointed a Committee on Indexing 

 Chemical Literature, and in 1884 the Chairman 

 of that Committee reported an agreement en- 

 tered into with the Smithsonian Institution 

 whereby the latter consented to publish In- 

 dexes to Chemical Literature upon recommen- 

 dation of the Committee. The booklet under 

 review forms one of this series. Mr. Mathew's 

 plan has much to approve ; he gives a synopsis 

 of the methods of preparation, physical and 

 chemical properties of the known carbides, con- 

 sidering them in alphabetical order, and follow- 

 ing each are the references to the literature 

 bearing thereon. 



Examination of this review shows that Henri 

 Moissan has contributed more to our knowledge 

 of the metallic carbides during the last five 

 years, thanks to his electric furnace, than all 

 chemists had done in previous years. The pro- 

 duction of acetylene gas from calcium carbide 

 seems to have been announced first by Wohler 

 in 1862. No commercial use was made of this 

 fact, however, until about 1893, when the Will- 

 son Aluminum Company, in this country, while 

 experimenting upon the reduction of the alkali 

 earths by means of carbon, found that calcium 

 carbide was formed ; this was regarded as a 

 waste product until its properties of readily de- 

 composing with water and yielding acetylene gas 

 established its commercial value. Mr. Mathews, 

 writing in 1897, says : " The cost of production 

 is still rather high and the chances of acetylene 

 gas being generally introduced for lighting pur- 



