H II. IF. HK 
ANKI'KN 
p^d.] ADDITIONS TO THE ALUNITE-JAROSITE GROUP. 41 
It has seemed to the writers best to designate the new compounds 
described in this article as natrojarosite and plumbojarosite, the names 
signifying their relation to a well-known species. Other members of 
this group will doubtless be found, and the name " natroalunite " might 
be employed to designate the two varieties of alunite from Colorado 
mentioned on page 37, where the prpportion of the soda to the potash 
molecule is 7 : 4. It is highly probable that a series of alunite-jarosite 
compounds could be made artificially. 
It is with pleasure that the writers acknowledge their indebtedness 
to Messrs. Turner and Porter for calling attention to the interesting 
compounds described in this article. 
