194 F. W. Clarke — Tschermatts Theory of the 



analyses exist for a species, a considerable variability becomes 

 manifest, which must influence all attempts to fix the molecular 

 structure. 



Taking now the analyses as cited by Tschermak, a number 

 of them reduce at once to the same type of substitution 

 formula as that which I have assigned to the orthochlorites. 

 Uniting like oxides," Fe 2 3 with Al 2 O s , MgO with FeO, etc., 

 we get at once the following expressions from the analytical 

 data. The name of the analyst follows the name of the species : 



Daphnite, Zeynek, Fe" S9 (SiO 4 ) 40 . H 15 A 44 M 2 , 



Chamosite, Boricky, Fe" 42 (Si0 4 ) 43 . H„A M M„ 



Delessite, Pufehl, Mg 49 (SiOJ S0 . H 18 A 4 .M M 



Thuringite, Gintl, Fe* 4] (SiOj„ . H^A. 



Keyser, Fe" 44 (SiO 4 ) 40 . H 11 AJ£ lJ 



An approximation to close agreement with theory is evident 

 at a glance ; but a better conception of the agreement may be 

 obtained by calculation, using the following formulae : 



Daphnite, Fe 2 (Si0 4 ) a A 2 (FeOHi 1 H ] 

 Chamosite, " " " 



Delessite, ( 1 Fe 2 (Si0 4 ) 2 A„(FeOH) 1 H I 



(Fried richsroda) \ 3 Mg 2 (Si0 4 ) 2 A 2 M 1 H 1 



/ 1 Fe,(Si0 4 ),H 4 



Thuringite, j 3 Fe o (Si0 4 ) 2 A 2 (Fe0H) 1 H 1 



I 1 Fe 2 (Si0 4 ) 2 A 4 



To this list we may add the thuringite from Lake Superior, 

 analyzed by Penfield and Sperry, which becomes 5Fe 2 (Si0 4 ) s 

 (FeOH) 4 +9Fe 2 (Si0 4 ) 2 A 4 . The analyses, reduced to typical 

 form and to 100 per cent, as is usual, are as follows : 





Daphnite. 

 Zeynek. 



Chamosite. 

 Boricky. 



Delessite. 

 Pufehl. 



Thuringite. 

 Gintl. 



Thuringite. 

 Keyser. 



Thuringite 

 P. &S. 



SiO„ 



23-44 



25-i7 



29-75 



23-58 



24-15 



21-35 



A1„0, 



22-08 



18-41 



20-58 



25-11 



25-44 



24-02 



FeO 



43-41 



45-37 



19-42 



40-08 



39-39 



43-88 



MgO 











17-53 















H 3 



11-07 



11-05 



12-72 



11-23 



11-02 



10-75 



lOO'OO 100-00 100-00 100-00 100-00 100-00 



Calculated from the formulae just given they become : 



Daph. & Cham. Deless. Thuring. G. & K. Thuringite, P. & S. 



SiO„ 



24-39 



30-30 



23-81 



21-54 



AiA 



20-73 



20-60 



25-30 



23-54 



FeO 



43-90 



18-18 



39-29 



44-31 



MoO 







18-18 











H 2 



10-98 



12-74 



11-60 



10-61 



100-00 100-00 100-00 100-00 



