34 Clarice and Steiger — Action of Ammonium Chloride. 



Upon grinding the powdered mineral with ammonium 

 chloride in an agate mortar, a distinct smell of ammonia was 

 noticeable. Three tubes of the mixture were heated to 350°, 

 and one exploded because of the liberation of gas within. 

 Upon opening the second and third tubes, a strong outrush of 

 ammonia was observed. When the contents of these tubes 

 were leached with water, large quantities of ferrous chloride 

 went into solution ; which, rapidly oxidizing, formed a deposit 

 of brownish hydroxide, and interfered seriously with filtra- 

 tion. The greater part of the lime in the ilvaite was dissolved 

 also. The washed residue, containing much ferric hydroxide, 

 was partially analyzed, and enough data were obtained to show 

 that a general breaking down of the ilvaite molecule had been 

 effected. Apparently, also, small quantities of an ammonium 

 derivative had been formed ; but this point is uncertain. The 

 original mineral was analyzed by Dr. W. F. Hillebrand ; and 

 his analysis, contrasted with that of the leached residue, is 

 given below. 



Ilvaite (Hillebrand). Residue (Steiger). 



Si0 2 29']6 43-01 



A1 2 3 , -52 ) 



Fe 2 3 _ 20-40 f 4008 



FeO __ 29-14 8-75 



MnO 5-15 -85 



CaO ._ 13-02 2-25 



MgO _ -15 undet. 



Na 2 0. -08 undet. 



NH 2 -88 



H 2 at 105° -15 undet. 



H 2 above 105° 2-64 undet. 



CI _ small amount. 



100-41 95-82 



In the leached residue from the third tube 21*37 per cent of 

 soluble silica was found ; silica which had been liberated dur- 

 ing the reaction between the ilvaite and the ammonium 

 chloride. In short, ilvaite behaves towards the reagent much 

 like pectolite, and the product is a mixture of uncertain char- 

 acter. The evident instability of the ilvaite molecule may 

 account for its rarity as a mineral species. Only exceptional 

 conditions would favor its formation. 



Biebeckite f 



The results obtained with ilvaite made it desirable to study, 

 for comparison, some other silicates of iron. Among these 

 the mineral from St. Peter's Dome, near Pike's Peak, Colo- 



