102 



SCIENCE. 



[N. S. Vol. V. No. 107. 



count." " I am a determined opponent of 

 what I think may fairly be termed the non- 

 sensical hypothesis of ionic dissociation (italics 

 ours), for there is no other appropriate 

 term for a view which asserts that hydro- 

 gen chloride and a few other compounds 

 are so loosely strung together that they fall 

 to pieces when dissolved in water ; out of 

 sheer fright, it would seem, as no valid mo- 

 tive is suggested for such self-sacrifice; and 

 no such charge of unprincipled levity of 

 conduct is brought against the vast major- 

 ity of compounds other than a few acids and 

 alkalies." If there are others who oppose 

 the theory as strongly as Prof. Armstrong, 

 they at least have not the temerity to at- 

 tack it so boldly in the face of its tacit gen- 

 eral acceptance in the chemical world. 



In the December Journal of the Amer- 

 ican Chemical Society, George F. Payne 

 discusses the mineral constituents of the 

 watermelon. He finds in the ash over 

 sixty per cent, of potash and ten per cent, 

 of phosphoric acid; hence the need of fertil- 

 izers containing a large quantity of potash. 

 J. L. H. 



ASTRONOMICAL NOTES. 



We have received a new book on the de- 

 termination of planet and comet orbits by 

 Dr. Karl Zelbr. It contains 125 octavo 

 pages, and is reprinted from the first vol- 

 ume of Valentiner's Handworterhuch der As- 

 tronomie. It will doubtless be found a very 

 useful text-book of the subject. 



The Astronomical Journal of December 

 10th contains a series of observations of 

 the companion of Sirius made at Washing- 

 ton last March by Prof Stimson J. Brown. 

 At the time of making these observations 

 Prof. Brown did not consider them entitled 

 to very much confidence, on account of the 

 extreme diiBculty experienced in seeing the 

 companion so near the principal star. It 

 is now evident, however, from the later ob- 

 serva,tions at the Lick Observatory, that 



the Washington observations are correct, 

 and that the object seen by Prof. Brown 

 was really the companion. 



In the Astronomische Nachrichten of De- 

 cember 14th Prof. E. C. Pickering has a 

 note on a method of determining the rela- 

 tive motions of stars in the line of sight by 

 means of spectra photographed through an 

 objective prism. The plan consists of 

 making a pair of photographs of the same 

 region near the meridian in reversed po- 

 sitions of the telescope. As the reversal of 

 the telescope turns the spectra 180°, we 

 can measure on the photographs twice the 

 linear displacement due to the relative mo- 

 tions of any two stars in the line of sight. 

 The second photograph is made through the 

 glass plate, so that the plates may be placed 

 with their films in contact for making the 

 comparisons. 



Among recent series of meridian circle 

 observations of which preliminary accounts 

 have appeared in the astronomical period- 

 icals, we notice the following: In the Astro- 

 nomical Journal of December 23rd Prof. 

 Tucker gives a summary of the results of 

 his determinations of fundamental stars 

 contained in the astronomical ephemerides 

 other than the Berlin Jahrhuch. In the As- 

 tronomische Nachrichten of December 22d 

 Prof. Kiistner gives his determinations of 

 the Zusatzsterne of the Berlin Jahrhuch list, 

 made with the meridian circle of the Berlin 

 observatory in the years 1886 to 1891. 



H.J. 



SCIENTIFIC NOTES AND NEWS. 

 Gen. Francis A. Walker, President of the 

 Massachusetts Institute of Technology and 

 Vice-President of the National Academy of 

 Sciences, died suddenly on January 5th. He 

 was born on July 2, 1840, and graduated from 

 Amherst College in 1860. He had filled many 

 important positions, having been professor of 

 political economy in the Sheffield Scientific 

 School of Yale University, Chief of the Bureau 



