406 Clarke and Schneider — Experiments upon the 









Ripidolite. 



Prochlorite. 



Leuchtenbergite 



Si0 2 







29-87 



26-40 



32-27 



aia 







14-48 



22-80 



16-05 



Cr 2 O a 







1-56 









Fe 2 3 







5-52 



2-86 



4'26 



FeO 







1-93 



17-77 



•28 



NiO 







•17 









MnO 











•25 





MgO 







33-06 



19-09 



29-75 



CaO 















6-21 



H 2 







13-60 



12-21 



11-47 



F 











trace 









100-19 



100-38 



100-29 



H 2 Oatl05° 







•80 



•38 



cc 



250°- 



-300° 



•95 



•15 



•21 



(C 



383°- 



-412° 



•49 



•62 



( .... 



(( 



498°- 



-527° 







•09 



.... 



a 



red-heat 



11-74 



[ 10-55 



( 10-69 



a 



white-heat 



•42 



.._. 



•19 



Here again we have to deal with water which is plainly consti- 

 tutional. Hence the suggestion put forward by one of us that 

 the chlorites are essentially micas plus water of crystallization, 

 must be abandoned.* 



Upon treatment with dry hydrochloric acid gas at 383°-412°, 

 the three minerals differ considerably. The times of heating 

 and the bases converted into chlorides were as follows : 



Bipidolite. Prochlorite. Leuchtenbergite. 



Hours heated 19 31 34 



MsjO removed 13-46 1'54 6-29 



R„0 3 removed 4-24 2-17 -42 



Si0 2 removed .. -92 



In a second experiment with the ripidolite 58 hours of heat" 

 ing were required before constant weight was attained, and 

 13'36 per cent of magnesia plus 1-20 of sesquioxides were ren- 

 dered soluble. In a third experiment the heating lasted 30 

 hours, and the percentages of MgO and R„0 3 removed were 

 11-10 and 3 31 respectively. Even at the ordinary temperature 

 of the laboratory ripidolite was decidedly attacked by the 

 gaseous acid, 4/66 MgO and 343 R 2 3 becoming soluble. In 

 this case the experiment lasted 100 hours. In the case 

 of the prochlorite the result obtained is . of very doubtful 

 significance. In a mineral containing so large a proportion 

 of ferrous iron, secondary reactions due to oxidation are possi- 



* Clarke, "A theory of the mica group," this Journal, Nov., 1889. 



