426 Chronicles of Science. [Ji%j 



properties. The natural silicate is almost, if not quite, colourless, 

 aud yet it gives a spectrum which shows above a dozen narrow 

 black lines, much more distinct than even those characteristic of 

 salts of didymium. When melted with borax it gives a glassy bead, 

 clear and colourless both hot and cold, and no trace of absorption 

 bands can be seen in the spectrum ; but if the borax bead be 

 saturated at a high temperature, and flamed so that it may be filled 

 with crystals of borate of jargonia, the spectrum shows four distinct 

 absorption bands, unhke those due to any other known substance. 

 Further researches have shown Mr. Sorby that jargonia exists in 

 two distinct conditions, which have difl'erent specific gravities and 

 optical properties. The flamed borax beads give two entirely 

 difl'erent spectra, according to the temperature to which the enclosed 

 crystals have been exposed, and there is an analogous difference in 

 the silicates. On taking a pale-green jargon, which naturally 

 showed a mere faint trace of the absorption bands, and keeping it 

 at a bright red heat for some time, the specific gravity gradually 

 increased from 4*20 to 4 • 52, and the spectrum then showed all the 

 narrow black absorption bands in great perfection. It appears, 

 however, that Professor A. H. Church, M.A., pubhshed a similar 

 discovery nearly three years ago in the * Intellectual Observer.' 

 Not only did he describe bands, but he noticed their occurrence 

 in the spectra of some stones from particular localities, and their 

 absence from stones from other localities. He also added his views 

 as to the cause of these bands — the presence of an element in some 

 specimens, not found in others. An account of .Mr. Sorby 's further 

 discoveries in spectrum and microscopic analysis will be found 

 elsewhere. 



During an examination of the Heaton process for making steel 

 at Langley Mill, Mr. Crookes has noticed a remarkable instance of 

 the crystallization of iron. When the violence of the action be- 

 tween the molten iron and the nitrate of soda has subsided, the 

 lower portion of the apparatus, called the converter, is detached, 

 and after a few minutes the contents are tiu'ned out on to the floor 

 in the form of a porous mass of nearly | of a ton in weight. Upon 

 examining portions of this metallic sponge, it is found to consist of a 

 segregation of minute featheiy crystals of iron, apparently built up 

 of small cubes. The outlines of some of these are perfectly sharp, 

 and their appearance, especially in the cavities, is veiy beautiful. 



In February, 18C8, two Belgian chemists — MM, Graebe and 

 Liebermann — communicated a memoir on alizarine, from which an 

 intimate relation was acknowledged between this colouring matter 

 and anthracene. By heating ahzarine with zinc dust, they ob- 

 tained as the sole product of reduction a hydrocarbon having all 

 the qualities of antnracene. Having thus obtained anthracene as 



