Royal Society. 319 



Aluminium-ethide and methide occur as colourless liquids. The 

 ethide boils at 194°, and does not freeze at — 18°. The methide boils 

 at 1 30°, and solidifies at a little above 0° into a beautiful crystalline 

 mass. Both liquids take fire on exposure to the air, and explode 

 violently by contact with water. They are produced from mercuric 

 ethide and methide respectively by heating these compounds for some 

 hours in a water-bath, with excess of aluminium clippings. This 

 process was obviously suggested by Frankland and Duppa's new 

 reaction for making zmc-ethide, methide, amylide, &c. 



Al 2 + 3HgEt 2 =Hg 3 + 2 AlEt 3 . 



ROYAL SOCIETY. 



[Continued from p. 239.] 

 January 26, 1865. — Major-General Sabine, President, in the Chair. 



The following communications were read : — 



M On the Spectrum of the Great Nebula in the Sword-handle of 

 Orion." By William Huggins, F.R.A.S. 



In a paper recently presented to the Royal Society*, I gave the 

 results of the application of prismatic analysis to some of the objects 

 in the heavens known as nebulae. Eight of the nebulae examined 

 gave a spectrum indicating gaseity, and, of these, six belong to the 

 class of small and comparatively bright objects which it is convenient 

 to distinguish still by the name of planetary. These nebulae pre- 

 sent little indication of probable resolvability into discrete points, 

 even with the greatest optical power which has yet been brought 

 to bear upon them. 



The other two nebulae which gave a spectrum indicative of matter 

 in the gaseous form, are 57 M, the annular nebula in Lyra, and 27 M, 

 the Dumbbell nebula. The results of the examination of these nebulae 

 with telescopes of great power must probably be regarded as in favour 

 of their consisting of clustering stars. It was therefore of import- 

 ance to determine, by the observation of other objects, whether any 

 nebulae which have been certainly resolved into stars give a spec- 

 trum which shows the source of light to be glowing gas. With this 

 purpose in view I submitted the light of the following easily resolved 

 clusters to spectrum analysis. 



"4670. 2120 h. 15 M. Very bright cluster ; well resolved " f. 



"4678, 2125 h. 2 M. Bright cluster, well resolved." 



Both these clusters gave a continuous spectrum. 



I then examined the Great Nebula in the Sword-handle of Orion. 

 The results of telescopic observation on this nebula % seem to show 



* On the Spectra of some of the Nebulas, Phil. Trans. 1864, p. 437. 



t The numbers and descriptions are from Sir John Herschel's Catalogue, 

 Phil. Trans. 1864, part 1. 



J "The general aspect of the less luminous and cirrous portion is simply 

 nebulous and irresolvable ; but the brighter portion immediately adjacent to the 

 trapezium forming the square front of the head, is shown with the 18-inch 

 reflector broken up into masses, whose mottled and curdling light evidently 



