180 



SCIENCE. 



LN. S. Vol. V. No. 109. 



H. N. Waeeen contributes a short article 

 to the Chemical News on calcium carbid as a 

 new reducing agent. He finds that when 

 it is heated with many metallic oxids they 

 are reduced, forming generally alloj's of the 

 metal with a small amount of calcium. 

 Even the oxids of chromium, molybdenum 

 and uranium are readily reduced. Calcium 

 carbid, which is so cheap, may come to re- 

 place for reduction the more expensive 

 sodium or potassium. 



M. GuNTz, to whom has just been awarded 

 the Saintour prize of the French Academy 

 of Sciences, shows in a recent Comptes 

 Rendues that the lithium nitrid obtained 

 by him is not pure. Lithium combines 

 directly with nitrogen, but the nitrid on 

 formation dissolves a portion of the sub- 

 stance of the vessel in which the lithium is 

 contained. Iron is least readily attacked ; 

 silver, platinum, quartz and graphite-carbon 

 are readily acted upon, and cannot be used; 

 hence all of the lithium nitrid formed is 

 more or less contaminated by foreign mat- 

 ter. J. L. H. 



ASTRONOMICAL NOTES. 



The Nichols Press, of Lynn., Mass., has 

 published a large quarto volume of 258 

 pages by Dr. T. J. J. See, entitled ' Re- 

 searches on the Evolution of the Stellar 

 Systems.' Dr. See gives a comprehensive 

 account of the present state of our knowl- 

 edge of the binary sj^'stems, and, while he 

 includes but little matter which has not 

 already appeared in print, he has produced 

 a book which will certainly be of great in- 

 terest to students of the subject. 



The volume contains excellent accounts 

 of the methods in use for the determination 

 of binary star orbits, as well as reprints of 

 Dr. See's own recent articles published in 

 the Astronomische Nachrichten. These arti- 

 cles relate to the use of spectroscopic ob- 

 servations for the study of the binary stars 

 and for the application of a rigorous test 



of the universality of the law of gravita- 

 tion. They have been criticised in the 

 same journal in which they appeared, but 

 in the present volume no notice is taken of 

 these criticisms. Following the theoretical 

 introduction, Dr. See gives his determina- 

 tions of the orbits of forty stars, together 

 with the observations on which they are 

 based. We have not space to enter into a 

 detailed criticism of this part of the book, 

 but we are not sure that Dr. See's methods 

 will meet with the complete approval of 

 astronomers in general. Thus in the case 

 of Zeta Sagittarii, Dr. See says : " While in 

 Virginia recently I took occasion to meas- 

 ure this star, and, although the object was 

 seen with difficulty, owing to its low alti- 

 tude, I could discover a distinct elongation 

 in the direction 194°. 7 ; the distance could 

 not be fixed with much confidence, but my 

 settings of the micrometer gave 0".35. The 

 estimates of distance were substantially 

 the same, but I am now convinced, from 

 my distinct recollection of the appearance 

 of the object, that both the measure and 

 the estimate were too large." We doubt 

 whether recollections of the appearance of 

 a double star should have any place in 

 the discussion of an orbit. Another thing 

 which students might expect in the present 

 work is a series of extended ephemerides 

 computed from the orbits given by the 

 author. But the ephemerides usually ex- 

 tend for a year or two only, and this cir- 

 cumstance will diminish somewhat the 

 practical usefulness of the work. 



The observatory of Karlsruhe has issued 

 the fifth volume of its publications. We 

 find in it observations of stars south of the 

 equator, made during the years 1892 to 

 1894, together with a catalogue derived 

 from them. This volume is the last which 

 will be issued from Karlsruhe, as the observ- 

 atory has been moved to Heidelberg, where 

 new buildings have been erected on one of 

 the hills overlooking the Neckar valley. 



