206 



University of California. 



[Vol. 3. 





Analysis. 



Insol. deducted. 



Ratio. 



Calculated. 



CuO 



8.13 



9.22 



.95 



9.45 



FeO 



14.53 



16.47 



1.88 



17.08 



S0 3 



25.74 



29.18 



3.00 



28.53 



H,0 



40.34 



45.74 



20.88 



44.94 



Insol. 



11.80 











100.54 



100.61 





100.00 



Water was given off at the temperatures stated in the follow- 

 ing proportions : 



Ratio. 



H-,0 (102°) 34.68 17.96 or 5.99 



H 2 (above 102°) 5.66 2.92 .97 



Crystallographieally and optically the properties of the two 

 substances are identical. Some of the material was dissolved in 

 water, the gangue filtered off and the filtrate slowly evaporated. 

 A little sulphuric acid was added to prevent the precipitation of 

 the iron as a basic salt. Crystals were obtained, isomorphous 

 with pisanite, and having a definite ratio of FeO to CuO of 2:1. 

 A mixture of artificial sulphate of copper and iron in the proper 

 proportion was dissolved in water and allowed to evaporate. 

 Crystals were obtained, having the definite composition expressed 

 by the formula, 2FeO.Cu0.3SO a +21H 2 0. The crystals are 

 isomorphous with pisanite, and showed the forms, SOOli, |110|, 

 1 103}, ilOl}, |6ll I and \121\. The axial ratio calculated from 

 a few poor readings is : 



a: b : c = 1 .1739 : 1 : 1 .5218 ; /3 = 104° 30' 



The artificial salt corresponding to this formula has been 

 described by von Hauer and the crystals measured by Brezina,* 

 who made them triclinic. It is interesting to note that the 

 crystals of pisanite, described by Hintzef and of which a partial 

 analysis is given, also correspond fairly well with this formula. 

 His analysis gives only determinations of CuO and SO3. 

 Assuming that no gangue was present in his material, his analysis 

 becomes : 



*Pogg: Annalen 1865, p. 635. 

 t Zeitsch. Krys. 1878, 2, :i09. 



