EARTHS PROPER. 



Glucina 0-266 or 3-3681 



Muriatic acid 0-85962 - 4-625* 



The atomic weight of glucina deduced from this 

 analysis is 3*3681, which is a little higher than 

 that from the sulphate. But the preponderancy 

 of evidence is entirely in favour of 3-25, the 

 weight deduced from the sulphates of glucina. 

 Composi, 3^ T^Q emerald or bend is the mineral from 



tion of 



emerald, which glucina was originally obtained, and in- 

 deed, we are scarcely in possession of any other 

 quarry from which this earth can even at present 

 be procured. It is usually crystallized in six- 

 sided prisms, and has all the marks of being a 

 chemical compound. Its constituents are silica, 

 alumina, and glucina, with mere traces of some 

 metallic oxides, which seem to act the part of 

 colouring matters. It will be worth our while 

 to see what atomic weight will be deduced for 

 glucina from the constituents of this mineral. 



Vauquelin and Klaproth published good ana- 

 lyses of emerald and beryl ; but it will be better 

 to employ for our calculations the analysis by 

 Berzelius, which is much later, and which, from 

 the improvements introduced into the art of 

 analyzing minerals, is probably nearest the truth. 

 According to Berzelius, the constituents of this 

 mineral are as follows : t 



* Berzelius' Attempt, &c. p. 134. f Afhandlingar, IV. 192. 



