Chemistry and Physics. 549 



bun cli of very thin fibers, all differentiate this mineral from 

 hulsite, which never shows any indication of fibrosity. 



An alternative interpretation of the composition of paigeite 

 is that it is a mixture of hulsite and a fibrous borate. Sub- 

 tracting from the formula of paigeite the necessary amounts to 

 include all the tin with the hulsite, the following results are 

 obtained : 



Paigeite = 



= 30 FeO.5 Fe„(X 



.IS 



qO, 



.6B 2 3 .5 



H n O 





minus hulsite 



12 



a 



2 " 



1 



a 



3 " 2 



u 





there is left 



18 



a 



3 " 





a 



3 " 3 



u 



or 









6FeO.Fe 2 3 



.B 2 3 .H 2 0. 







Should future investigation prove this to be the case, then 

 the material now called paigeite would consist of a mixture of 

 1 part hulsite and 3 parts of the borate 6FeO.Fe 2 3 .B 2 8 .H 2 0, 

 to which the name of paigeite could then be referred. How- 

 ever, on the evidence at hand, it is most reasonable to regard 

 paigeite as homogeneous and with the composition ascribed 

 to it. 



To repeat, the formulae now proposed are, for hulsite, 

 12(Fe,Mff)0.2Fe o 0,.lSn0 s .3B,0,.2H,0, and for paigeite, 

 30FeO.5Fe 2 O 3 .lSnO 2 .6B 2 O 3 .5H 2 O. 



Chemical Laboratory, 



U. S. Geological Survey. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. A Gas containing Helium from the German Potash Deposit. — 

 Ernst Erdmann gives an account of an inflammable gas which 

 was set free by a blast in the carnallite deposit of a shaft at a 

 depth of 450 meters below the surface. When first liberated, 4^- 

 years ago, it burned with a flame a yard long, and the pressure 

 has since diminished only very gradually, and many thousands of 

 cubic meters of the gas have escaped and burned. As an average 

 of eight analyses the following results were obtained : 



Hvdrogen , 83*6 per cent by volume. 



Methane 4*4 " " " 



Residue 12-0 " " " 



The methane was found to be free from other hydrocarbons of 

 the series, and the absence of oxygen, carbon dioxide, ethylene, 

 and acetylene was established. The residue was found to contain 



