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XLIV. Remarks to show that the Nature of the Atmosphere con- 

 tradicts the Notion that the Air explains the Phcenomena of 

 the Skij. 



To Mr. Tilloch. 



1 April 1820. 



T having ocpurred to me that some appearances attri- 

 buted to the atmosphere are contradictory to the known proper- 

 ties of this environing fluid, and my objections having: received 

 some sanction from private friends ; in the hope that they may 

 receive a timely correction or stronger corroboration from your 

 able correspondents, I have drawn them up for your perusal and 

 most candid criticism. See fig. A. (PI. IV.) 



E the earth, aaa the atmosphere. 



Were the atmosphere of a like density throughout, its appear- 

 ance would be the same in everv direction, except where local 

 causes might effect a partial change in its phsenomena ; but these 

 excepted, the form and colour of the great body of the air would 

 necessarily impose upon the sight equality of distance and of 

 tint on every hand, unless the greater quantity of air from its ex- 

 terior tlirough the horizon to the eve might lessen the apparent 

 atmospheric distance there, and give its colour strength. 



The greater density of the air upon the general surface of the 

 earth, compared with its tenuity on mountains, has been irjost 

 fully proved; and, if it be not transparent in an absolute sense, 

 then much less quantity of atmosphere must be contained in the 

 r-ame measure of distance vertically from the eye than horizon- 

 tally; and consequently, the lower elevations of the sight could 

 not but discern a nearer and a stronger coloured indication of 

 the atmosphere than could be viewed above. 



Sir, yours respectfully, 



W, W. 



XLV. On the Alterationwhich Sulphuric Acid experiences in 

 acting upon Alcohol *. 



In Number 289 of the Annates de Chimie, there is a Memoir 

 by M. Dabit on Sulphuric Ether, in which he endeavours to 

 show that the action of sulphuric acid upon alcohol is not con- 

 fined, as Fourcroy and Vauquelin have supposed, to determining 

 the formation of water, on account of its great affinity for that 

 li(iuid; but that the sulphuric acid is really decomposed, that it 

 yields a portion of oxygen to the alcohol, without however passing 

 into the state of sulphurous acid ; and that it forms a new acid 

 ii>termcdiary between the sulphurous and sulphuric, 

 * From Ann. de CdkH'te, Jan. 18^0. 



In 



