254 Dr. Webster on the Calton Hill, [Oct. 



whether it is most expedient to throw off, or retain, the gas 

 generated during fermentation ; and whether it may be better to 

 admit or exclude the action of the atmosphere at that period. 



Having explained my ideas upon the art of making cyder, I 

 will shortly repeat my difficulties in the following queries ; and, 

 perhaps, some of the contributors to your journal will condescend 

 to favour me with their opinions upon a subject at the present 

 time of much interest and importance to the public. 

 I have the honour to be, Sir, 



Your very obedient servant, 



J. Venables. 



Queries. 



1. By what process is the excess of the malic acid in cyder 

 best neutralized ? 



2. What is the effect of boiling upon the malic acid ? 



3. By what process may the pulpy matter and other impuri- 

 ties expressed from the apples be best separated from the cyder 

 before fermentation ? 



4. Is the fermentation best conducted in strong vessels 

 entirely closed, or in vessels furnished with a valve for the 

 escape of the carbonic acid gas, or in vessels entirely open ? 



5. After fermentation do equal parts of the lees, and of the 

 purer cyder, contain equal quantities of spirit ? 



6. Is cyder weakened by racking after the fermentation has 

 ceased ? 



Article III. 



Remarks on the Structure of the Calton Hill, near Edinburgh, 

 Scotland ; and on the Aqueous Origin of Wacke. By J. W. 

 Webster, M.D. of Boston* 



The country around Edinburgh is extremely interesting to 

 the geologist, and presents numerous instances of the junction 

 of rocks to which the advocates of the Neptunian system have 

 referred in support of their opinion as to the aqueous origin of 

 greenstone, basalt, and wacke ; while the same examples have 

 been cited by the volcanists, and by those who hold an interme- 

 diate opinion. The structure of a portion of Calton Hill, where 

 the most distinct alternations of substances (whose aqueous 

 origin none can dispute) with pure and well characterized wacke 

 are displayed, has not as yet, I believe, been particularly 

 described. 



Edinburgh is situated nearly in the centre of an extensive coal 

 formation, where the usual sandstones and other coal measures 



• From Silliman's American Journal of Science, vol. i. p. 230. 



