418 



SCIENCE. 



[N. S. Vol. VII. No. 169. 



U Pegasi, Pickering concludes that the star 

 exhibits a principal and secondary mini- 

 mum, at magnitudes 9.90 and 9.75 respec- 

 tively, in a period of nine hours. Chandler, 

 however {Astronomical Journal, XVIII., p. 

 140), regards this difference between the 

 minima too slight to be conclusive, and de- 

 rives from his own observations (with the 

 omission of his first estimates by which he 

 discovered the star's variability) a simple, 

 symmetrical light curve, with a period of 

 four and one-half hours. 



The number of variables in star clusters 

 discovered by Bailey on the Harvard plates 

 has been increased by his further study of 

 them, so that now the clusters oj Centauri, 

 Messier 3, Messier 5 and N. G. C. 7078 

 have been found to contain, respectively, 

 122, 132, 85 and 51 variable stars, or 390 

 in all. 



E. B. F. 



NOTES ON INORGANIC CHEMISTRY. 

 Some weeks since attention was called in 

 these notes to the formation of ammonium 

 peroxid, or rather a compound of ammo- 

 nium peroxid and hydrogen peroxid, by P. 

 Melikoft' and L. Pissarjewsky at the Uni- 

 versity of Odessa. To this compound, which 

 is formed by the action of ethereal solution 

 of ammonia upon a similar solution of 

 hydrogen peroxid, the formula {TSK^fi.^, 

 2H2O2,10H„O was given. An article in the 

 last Berichte gives further particulars of 

 the compound and assigns the formula 

 (NHj),0„H,0,,Hp. The water is con- 

 sidered as water of crystallization, and is 

 apparently not constant, as in one speci- 

 men the water present corresponded to 

 (]SrHJ,02,H,0,,iH,0. It is possible, how- 

 ever, to consider the substance as NH^O,H, 

 the peroxid of ammonium hydroxid. From 

 the relative stability of ozone and hydrogen 

 peroxid it is not improbable that their 

 constitutional formulae should be written 



TT 



0=:0":z:0 and >0"z:0, one atom of 

 H 



oxygen being considered quadrivalent. If 

 this be the case, the formula of ammonium 



NH 



peroxid might be *>0" 



:0. 



In the same Berichte account is given 

 of some new compounds in which a part 

 of the oxygen in sulfates and phosphates 

 is replaced by fluorin. Types of tliese 

 compounds are HKjS^O, Fl^.H^O and 

 HRbjPOgFljH.O. These interesting sub- 

 stances are fairly stable and are closely 

 related to the fluoriodates, not long since 

 discovered by Professor Weiuland, to whom 

 we are also indebted for these fluosulfates 

 and fiuorphosphates. 



At the last meeting of the Chemical Soci- 

 ety (London) a paper was read by W. A. 

 Shenstone and Beck, on the influence of 

 the silent discharge of electricity on atmo- 

 spheric air. At first there is a large con- 

 traction and this is followed by a re-expan- 

 sion to nearly the original volume, and a^ 

 trace of nitrogen peroxid is present. 



The explanation offered is that at first 

 the oxygen in the air is condensed to ozone. 

 In air it appears that owing to dilution 

 with an inert gas, nitrogen, from 80 % to 

 90 % of the oxygen can be converted into 

 ozone. This causes the^first contraction. 

 When the oxygen is al uost completely 

 changed into ozone some small amounto 

 nitrogen dioxid is formed. This at once 

 attacks the ozone molecule and breaks it 

 down under the influence of the silent dis- 

 charge, and the gas returns to its original 

 volume. As confirmatory of this theory is 

 the fact that not a trace of ozone can be 

 made in the presence of nitrogen peroxid. 

 J. L. H. 



SCIENTIFIC NOTES AND NEWS. 



THE ALLEGHENY OBSEEVATORY. 



Professor James E. Keeler has written a- 

 letter to the Chairman of the Observatory Com- 

 mittee stating that he is prepared to decline 

 the call to the Directorship of the Lick Obser- 



