>"t>4 Washington — Constitution qfSomt Salic Silicates. 



in the base, nor as aluraino-silieates, and Clarke furthermore 



regards them as substitution derivatives of aluminnin silicates. 



The present hypothesis differs From these views in that : (1), 



the acid radicals Si : O s and SiO, are not regarded as mutually 



equivalent and isomorphonsly replaceable, as this is contrary to 



the accepted principles of isomorphism: (2), the feldspars, 

 leoads, zeolites, and scapolites are regarded as salts of two alu- 



mino-silicic acids H.AlSi„O s for the first three and H 10 AlSi 3 O 12 

 for the last; (3), the hydrogens of these acids are assumed to 

 be replaced, not by independent and variable atoms, but by 

 atomic groups, here called " integrals," whose total valence is 

 that of the basic hydrogens. 



Attention must be called to the fact that, under the usual 

 interpretation of the feldspars as silicates, the acids being 

 RSiAX and H ; Si,(X. the groups (NaAl)" and (CaAl„) viii are 

 essentially " integrals '- exactly in the sense of those suggested 

 in this paper. 



Illustrations. — In the following pages will be given the con- 

 stitutional formulas of the minerals under consideration, each 

 group being followed by a brief discussion of some pertinent 

 points. The names of the several integrals and appropriate 

 names for the minerals, in accordance with a recently suggested 

 mineral nomenclature,* have been coined, but are not given 

 here, as introducing unnecessary complications. They will 

 appear in a subsecpient paper. 



Feldspar Group. 

 Adular Subgroup, monoclinic or pseudomonoclinic. 



Orthoclase, (KSi)AlSi a O B Soda . orthoc]ase i ™(KSi)AISi,O e ) 

 Barbierite, (NaSi |AlSi,0 &0Cla ortllocIa * e > ( n (NaSi> AlSi 2 9 f 



Celsian, (BaAl)AlSi,O s Hyalonhane -I ™(KSi)AlSi,O e ) 



Uvalopnane, -j „( B aAl)AlSi a 8 f 



Albite Subgroup, triclinic. 



Microcline, (KSi) AlSi„Cv Anorthite, (CaAl)AlSi 2 8 



Albite, (XaSi)AlSi 2 ' Carnesieite, (Xa 2 Al)AlSi„0 8 



Calcium albite, (CaSi 2 )(AlSi s O e ), 



Mixed Salts. 



. ,, , j m (KSi)AlSi 8 | 



Oliffoclaae ( \h \n ) - { 2(NaSi) AlSi.0, / 



Uligoclase, (Ab 2 AnJ, , 1(CaA ] )A1S i O. | 



( 4(KSi)AlSi,O e ) 



Sigterite, -' 2(NaSi)AlSi t O, [ 

 ( 9<Na s Al)AlSi,O e ) 



*H. S. Washington, this Journal, vol. xxxiii, p. 137, 191'!. 



