312 



Mr. Henliell on the Mutual Action 



+ 0-88807 

 + 0-72029 

 + 0-5524.0 

 + 0-38147 

 + 0-21650 



-16778 

 — 16789 

 -16793 

 -16797 



-11 



— 4 



— 4 



+ 7 

 



If we have calculated for an odd hour in which the term T 

 is contained, the formula for the interpolation of the column 



«is a + t.b + ^.c + 



' ^ a + &c. = 



2. 3 



a + t^f^b- 



d + 



1 



"6~ " ■ 2 



whence we obtain for our example 

 p = — 0-66532 



+ -^d, 



. 0-00005 — /- . 0-000007 



q = + 0-55240 

 V = _ 0-167904 



q' = — 0-1679U4 —/. 0-00002 + /-. 0-000006 

 But I do not believe that one can ever have an object in 

 going beyond the second differences, or in making the calcu- 

 lation for more than three hours : if the accuracy were to be 

 pushed to a greater degree, it would likewise be necessary to 

 apply a greater number of decimals than is here done. 

 [To be continued.] 



LI V. Oji the Mutual Action of Stdphin-ic Acid and Alcohol, 

 and on the Nature of the Process by 'which JEther is formed. 

 By Henry Hennell, Esq. Communicated by William 

 Thomas Brande, Esq. F.R.S.* 



1, T WAS some time since engaged in an investigation of 

 -*• the nature of oil of wine and of the salts called sulpho- 

 vinates : the results I obtained were considered of sufficient 

 importance to be honoured with a place in the Philosophical 

 Transactions f. The oil of wine and sulphovinic acid are sub- 

 stances produced during the mutual action of sulphuric acid 

 and alcohol in the well-known process adopted for the pre- 

 paration of asther ; and an important point with me, during 

 the above investigations and since that time, has been to deve- 

 lop the particular changes which take place when asther is 

 formed from sulphuric acid and alcohol. 1 perceive by the 

 Annales de Chimie for November last, that MM. Dumas and 

 Boullay have been engaged on the same subject, and have ex- 

 perimented on and considered, not only the formation of a3ther, 



* l-'iom tlie Pliilosophical Transaction!, for 1828. Part I. 

 t Phil. Trans. 1826. Pari ill. 



but 



