410 Scientific Intelligence. 



and masterly manner — in fact the names of the editors and of the- 

 special contributors are a sufficient guarantee of the excellence of 

 the whole. The unavoidable brevity of treatment will sometimes 

 be regretted and the amount of abbreviation may seem to an 

 occasional reader a serious drawback ; but this disappears upon 

 frequent use. Subjects in general chemistry have not been neg- 

 lected and we note, for example among the numerous excellent 

 articles, one by Mr. Muir upon atomic and molecular weights (24 

 pages), others by Dr. W. Ostwald on affinity, by Prof. E. Ray 

 Lankester on bacteria, by Prof. J. J. Thomson on states of 

 aggregation, and chemical equilibrium, by Prof. T. E. Thorpe on 

 the atmosphere, combustion and flame, by Prof. F. W. Clarke on 

 elements and Prof. Ira Remsen on equivalency and formula?.. 

 The completion of the entire work will be looked forward to with 

 much interest, and the gratitude of chemists is due to those who 

 have been willing to undertake so great a labor. It is a matter 

 of regret that the author who projected the work and whose name 

 it bears could not have lived to see its completion. 



3. A Treatise on the Principles of Chemistry ; by M. M. 

 Pattison Muir. Second edition. 490 pp. 8vo. Cambridge, 1 889,. 

 (University Press). — The second edition of this philosophical 

 work will be warmly welcomed by all who have become acquainted 

 with the excellence of the first edition published five years ago 

 (see this Journal, vol. ix, 255). Rapid progress has been made 

 during this period in the development of chemical principles, and 

 this has necessitated the fundamental revision of much of Book 

 I on Chemical Statics, and the entire rewriting of Book II on 

 Chemical Kinetics, especially that part dealing with chemical 

 affinity. The chemical student will find the modern ideas on both 

 branches of the subject presented in a very satisfactory and in- 

 structive form. 



4. Definitions adopted by the International Congress of Elec- 

 tricians. — Professor Mascart communicated to the French Acad- 

 emy the following definitions proposed by the late Congress of 

 Electricians : — 



Unit of Work, the Joule. Equal to 10 T C.G.S. units. It is the 

 energy equivalent to the heat produced by one ampere through 

 one ohm in one second. 



Unit of Power, the Watt. Equivalent to the power produced 

 by one Joule in one second and is equal to 10 7 C.Gr.S. units. 



The Quadrant is the unit for coefficient of induction. The 

 quadrant is expressed as a length and is equal to 10 9 centimeters. 



The frequence of an alternating current is the number of periods 

 per second. 



The actual strength of an alternating current is the square root 

 of the mean square of the strengths. 



The actual electromotive force is the square root of the mean 

 square of the electromotive forces. 



The apparent resistance of the current is the factor by which 

 one must multiply the actual strength in order to obtain the actual 

 electromotive force. 



