98 



Cross and Eakins — New occurrence of Ptilolite. 



The obtaining of material for chemical analysis was in this 

 case even more difficult than with the original ptilolite. About 

 six cubic feet of the rock was broken up and the tufts and 

 balls of the downy mineral removed with a curved needle. 

 After several days work with an assistant an amount was 

 obtained which on final purification gave a trifle over half a 

 gram of pure material. This final purification, as in the case 

 of the original ptilolite, was made by stirring the mineral in 

 water, breaking up the felt-like aggregates as far as possible, 

 allowing the heavier portion to settle, and pouring off ; this 

 operation being repeated upon the residue until most of the 

 ptilolite was washed out. The collected washings were allowed 

 to settle over night, the bulk of the water syphoned off, and 

 the stirring and pouring off repeated until a product was 

 obtained in which no gritty substance whatever could be de- 

 tected on careful testing with the rounded end of a glass rod. 

 The material so obtained, after drying on the water bath, was 

 left loosely covered, exposed to the air for several days. Dried 

 for eight days over sulphuric acid it lost 3*84 per cent, all of 

 which was regained in twenty-four hours in the air, and in this 

 condition it was analyzed. Like the original mineral this new 

 ptilolite is but very slightly attacked by hydrochloric acid, 

 and the prolonged action of hot concentrated sulphuric acid is 

 required for complete decomposition. 



Analysis and ratios (Analyst, L. G. Eakins) : 



SiO„ 67-83 1-131 10-1 



A1„0 3 11-44 -112 1-0 



CaO 3-30 -059 ) 



K 2 0-64 -007- -109 -98 



Na„0 2-63 -043) 



H„0 13-44 •747 6-67 



99-28 



The water was fractionated as follows : 



At 110° 2-62 



125° 1-31 



300° 5-41 



red heat 3-10 



13-44 

 Loss over HSO, 3-84 



•301 



1-79 



•073 



•65 



•301 



2-69 



•172 



1-54 



•213 



•190 



For comparison with the above, the analyses and ratios of 

 the original ptilolite and of mordenite are appended : 



