Intelligence and Miscellaneous Articles. 237 



fluorine belong to the aluminium, one- fourth to the lithium and so- 

 lium, thus in the proportion of 5 equiv. to 2 eq. In the remaining 

 double phosphate the quantity of oxygen in the alumina is half as 

 great as that in the phosphoric acid, that of the alkalies amounts to 

 a third part of the former. Whilst the alumina of the phosphate 

 contains five times as much oxygen as the aluminium of the fluoride 

 which is converted into alumina, we thus obtain ' ' ' ' ' '' '"'" '" 



(5R3 O 3P2 0, + 5Al, 0, 3P2 O,) + (RFl + 2A1 3F1) 

 as the formula for amblygonite. ! 



It has been previously mentioned, that ammonia throws down 

 phosphate of alumina from the solution of the amblygonite in sul- 

 phuric acid. The quantity in one experiment amounted to G8-33 

 per cent, of the mineral, and consisted of 3r71 phosphoric acid and 

 36*62 alumina, consequently it was SAlaOgSPgO^, i.e. the same 

 phosphate as the formula requires. — Poggendorff's Ann. Ixiv. p. 251. 



. ,. [Tq he ontinued.] 



■■■A i -: > - /iatiBJo hoffiim ^CHiULitUiit ariJ ulJwisarii 



THE GREAT symmetrical' BAROMETRIC WAVeI 



yr 



In the report on Atmospheric Waves which I had the honour to 

 present to the British Association for the Advancement of Science 

 at its last meeting, there is one point of great interest, and which it 

 is very desirable to investigate further ; I allude to the recurrence 

 of the great symmetrical barometric wave, an engraving of which is 

 inserted in the Report of the Thirteenth Meeting of the Association. 

 This wave, extending over thirteen days, was first observed in No- 

 vember 1842; the apex passed London about noon of the 18th. 

 Its return in 1843 occurred about noon of the 1 4th, with a rise and 

 fall of nearly the same period ; and in 1 844 a nearly similar rise and 

 fall of the barometer took place, — the epoch of the transit of the 

 crest, October 27, about noon. These almost regular barometric 

 oscillations render the barometric movements of the months of Oc- 

 tober and November highly interesting. It is accordingly proposed 

 that meteorological observations, on a similar plan, should be made 

 as extensively as possible, with a view to observe this particular 

 wave, should it again return ; and meteorologists are invited to direct 

 their particular attention to the oscillations of the barometer during 

 these months. 



Times of Observation. — The following hours are the most suitable 

 for the object now in view : — 3 a.m., 9 a.m., 3 p.m. and 9 p.m. ; 

 these hours divide the day into four equal parts ; they have been re- 

 commended by the Royal Society as meteorological hours, and are 

 the hours at which observations are made daily, by direction and 

 under the superintendence of the Honourable the Corporation of the 

 Trinity House, which have been most advantageously used in the 

 examination of atmospheric waves. 



In cases, however, in which the observation at 3 a.m. may be in- 

 convenient or impracticable, it will be important to substitute for it 

 two obgervations, one at midnight and the other at 6 in the morning. 



