Septembee 9, 1898.] 



SCIENCE. 



•329 



sodium orthroborate, and also by treating 

 the latter salt with hydrogen peroxid. The 

 sodium salt, NaBO^, 4HjO, and the ammo- 

 nium salt, NH^BOj, HjO were formed and 

 while powerful oxidizing agents are quite 

 stable. These are the only compounds of 

 quintivalent boron known, though from the 

 second method of formation the possibility 

 of their constitution being NH^ BO^, H^Oj, 

 and NaBOj, H^Oj, SH^O would seem not to 

 be excluded. 



Much discussion has been occasioned by 

 the announcement of the discovery of new 

 gases in the atmosphere. Professor Berthe- 

 lot calls attention in the Comptes Eendus to 

 the fact that the green line of krypton 

 almost exactly coincides with the green line 

 of the aurora spectrum, and suggests that 

 the element should, therefore, be called 

 eosium. Dr. Arthur Schuster in Nature 

 shows the spectrum of metargon to resem- 

 ble closely that of carbon plus that of 

 cyanogen. In replying, Professor Eamsay 

 recognizes the great similarity, but produces 

 evidence which seems to render it very im- 

 probable that any form of carbon could be 

 present, as the metargon spectrum remains 

 the same in spite of every effort to remove 

 any possible carbon present either as an ele- 

 ment or a compound. 



The element calcium has generally been 

 described in text-books as a yellow metal. 

 This color is evidently due to impurities, as 

 M. Moissan has recently obtained pure cal- 

 cium, in the form of brilliant white hex- 

 agonal crystals. The crystals were ob- 

 tained by dissolving the metal in liquid 

 sodium at a low red heat and removing 

 the sodium by means of the cautious use of 

 absolute alcohol. Calcium can also be ob- 

 tained by the electrolysis of fused calcium 

 iodid. Each of these methods yields a 

 metal over ninety-nine per cent. pure. 



In the Comptes Eendus Moissan also shows 

 that the metal calcium burns strongly in 



hydrogen forming a hydrid CaH,, which is 

 transparent, cystalline and stable. It is de- 

 composed by water with great violence, 

 hydrogen being evolved. It is not, like the 

 the corresponding hydrid of lithium, decom- 

 posed by being heated in nitrogen. In 

 order to distil pure lithium the metal must 

 be kept in an indifferent gas, and for this 

 purpose hydrogen or nitrogen will not 

 serve, as lithium combines directly with 

 both. The only gases which would be re- 

 ally indifferent would be argon and helium. 

 According to Nature the latest statistics 

 show a total of 6,144 chemical works in 

 Germany, employing over 125,000 persons. 

 In the Hamburg district 4,000 are employed, 

 as compared with 1,300 ten years ago. This 

 shows the rapid growth of these industries 

 in Germany in the last few years, a fact 

 which is attracting the attention of Eng- 

 land and other countries as well. 



J. L. H. 



SCIENTIFIC NOTES AND NEWS. 



COLOE-VISION. 



Mr. T. C. Poetee has given a communica- 

 tion to the Eoyal Society (presented by Lord 

 Rayleigh and printed in the Proceedings, June 

 30) on the flicker phenomenon. He found, 

 among other things, making use for this pur- 

 pose of a cardboard disc half black and half 

 white, viewed in the different colors of the spec- 

 trum of the second order of a Rowland's plane 

 diffraction grating of 14,434 lines to an inch, 

 that the greater the duration of the stimulation 

 of the retina by the colored light the shorter 

 the time during which it continued to be undi- 

 minished in amount, and that, with some ex- 

 actness, one of these quantities is inversely 

 proportional to the other. This inverse pro- 

 portionality is known to hold between the 

 brightness of the stimulus and its undiminished 

 duration ; it is now seen that when the bright- 

 ness is constant a longer period of exposure 

 plays the same part as a greater luminosity as 

 regards its undiminished continuance. 



It has been shown by Professor Albertoni 

 that there is a close relation, in the de- 



