Notes and Memoranda. 159 



"with, other elements. With regard to aluminium, Deville has shown 

 that two litres of gaseous chloride of aluminium = 55 criths of 

 Al + 6 times 35"5 criths of CI : — the atomic weight then of Al = 55, 

 and the formula of the chloride is consequently Al""" Cl 6 , or 

 All C],. 



"Which determination of the atomic weight is right ? Specific 

 heat says one thing, vapour density another. But take the vapour 

 density of another aluminium compared. Dr. Odling finds that two 

 litres of aluminium methide, or ethide vapour, contain only 27*5 

 criths of aluminium ; Al"' Cl 3 is, therefore, the right formula for 

 the chloride and the atomic weight of Al = 27'5. This deter- 

 mination of the atomic weight by the vapour density of the new 

 bodies thus confirms the results deduced from the specific heat of 

 the metal itself. The vapour density of the chloride is not an 

 adequate guide, being, as is the case with some other chlorides, 

 anomalous. 



In the concluding part of his discourse Dr. Odling illustrated 

 the properties of the new substances made by Mr. Buckton and 

 himself; namely, the aluminium methide, a compound of the 

 organic radicle methyle (C H 3 *) with aluminium, thus — Al Me 3 f ; 

 and aluminium ethide Al Et 3 ; Bt representing ethyle, 2 H 5 . 

 These bodies occur, according to the temperature, either in crystals 

 or in the liquid, or in the gaseous form : they are spontaneously 

 inflammable, and explode under water. They are made by digesting 

 the mercury compounds of methyle and ethyle respectively, with 

 aluminium clippings. 



NOTES AND MEMORANDA. 



Meteor observed at Sea. — The following communication has been received 

 from Joseph D. Dickinson, Esq., late 4th Regiment, and was written by him on 

 the voyage to New Zealand, a few days before landing : — " On board ship ' British 

 Trident,' October 23rd, 1864. We were yesterday in lat. 46° 49' south, and long. 

 124° 12' east, when, at about ten o'clock p.m., our attention was drawn to a very 

 brilliant streak of pale light, extending right across the heavens from east to west. 

 The side of the streak next to the south was well defined, that next the north not 

 so well. In breadth it was about 7°, but narrowed a little, and was less brilliant 

 towards the extremities. When I first caught sight of part of it, between two 

 sails, I thought it was the tail of a comet, which, indeed, it much resembled ; but 

 when I saw more of it I knew I was wrong. There was at the same time a clear 

 pale light in the south, from which I could, for a short time, distinguish a very 

 faint ray extending upwards. This part of the heavens was, however, soon ob- 

 scured by a thick bank of clouds, which rose up so as effectually to prevent our 

 seeing anything more in that direction. The streak overhead lasted (sometimes 

 fading a little, and then getting bright again) .until quarter-past eleven p.m., when 

 it appeared to break up into a number of streaks like tails of comets, extending 

 from the southern side of the original streak in an E.N.E. direction, the wind at 

 the time being W.N.W. These remained very bright for a few minutes, and then 

 faded away. During the whole time there were no clouds to be seen, except the 



* C = 12. f Al = 27-5. 



