

Chemical Examination of Algerite. 



105 



Silica, 

 Alumina, 

 Peroxyd of iron, 

 Magnesia, 

 Potash, 



Soda-traces, 

 Water, . 

 Lime, 



Carbonic acid, 



49-82 contains oxygen 26-60 

 24-91" 



1-85 



115 



1021 > contains oxygen 21-11 



2-20 

 1-74 



7-57 

 3-94 



J 



99-45 



The composition of the mineral, deducting the carbonate of 

 lime, is evidently a hydrated silicate of alumina and potash, in 

 which small quantities of magnesia and iron, replace in part the 

 alumina and water. Representing k\% (aluminicum) as Al?, and 

 Fe^ (ferricum) as Fe?,* we have, taking silica as Si O, and con- 

 sidering the Mg as replacing in part H and Fej?, the following for- 

 mula as very closely expressing its constitution, 5SiO.,-|-4HO, 

 KO, 6 T % AlpO, -a Fe(*0 or 5Si O , + 12MO, wh ich if we take sil ica 

 as SiO is evidently at once brought to Si 5 M x O p , or in M. Ger- 



hardt's notation Si 



M 8 O n , 



which is one of the typical forms 



which M. Laurent has deduced from his researches on the natural 

 silicates. This requires a ratio between the oxygen of the silica 

 and that of the other oxyds of 5 : 4, and that of the silica being 

 £o 60, theory demands for the bases 21-28 while experiment gives 

 21*11. Although it will be difficult to arrange the elements found, 

 m a satisfactory manner, according to the ideas of the dualistic 

 school, this close correspondence establishes beyond a doubt the 

 type of the compound. 



I have deducted the carbonate of lime and determined the com- 

 position of the mineral for 100 parts, and then in accordance with 

 the above formula calculated its composition according to theory. 

 The two results are subjoined. 



Silica, 



Alumina, 

 Potash, 



Peroxyd of iron , 



Magnesia, . 

 Wat 



er 



Found. 



52 28 



26 08 



10-69 



1*93 



1-20 5- 11-05 



7-92 

 10010 



Calculnted. 



52 -08 



2611 



10-88 



2 45 



10-78 



8-33 

 99-85 



The attempts to represent the composition of the natural sili- 

 cates in accordance with the dualistic system, have tended per- 

 a P s m °re than anything else, to show its inadequacy to the 



"5 EEI L.- 



Am. 



July, 1849 



14 



