320 



Dr Davy on Carbonate of Lime 



Plate-glass is usually considered as a double silicate of 

 lime and soda, or of lime and potash. The following atomic 

 expressions ref)resent the different analyses contained in the 

 above table ; the amount of potash contained in the English 

 varieties of glass being very trifling, this oxide has been ne- 

 glected altogether in the construction of their formulae. 



Venetian plate-glass, 

 Bohemian mirror-glass, 

 French plate-glass, No. 1, 

 French plate-glass. No. 2, 

 British plate-glass, 

 London Thames plate-glass, 

 London and Manchester | 

 plate -glass, . } 



2K0, 3NaO, 5CaO, 22SiO, 



KO Ca 0, 4 Si . 



4NaO, CaO, 11 Si O, 



KO, 3NaO, 2CaO, 14SiO, 



2 Na 0, Ca O, 9 Si O, 



2NaO, CaO, 8 Si O, 



2NaO, CaO, 9SiOj 



— Quarterly Journal of the Chemical Society, No. vii. for Oc- 

 tober 1849, p. 208. 



On Carbonate of Lime as an ingredient of Sea-Water. By 

 John Davy, M.D., F.R.S. Lond. and Edin., Inspector- 

 General of Array Hospitals, &c. 



The manner in which limestone-cliffs, rising above deep 

 water, are worn by the action of the sea, as it were by a 

 weak acid, such as we know it contains, viz., the carbonic ; 

 the manner, further, in which the sand, on low shores where 



