1SS         «  ONTRIBXJTIONS   TO    ECONOMIC    GEOLOGY,  L906,   PART    I. 
the  temperature  of  the  steam  results  in  diminishing  the  output  and  i 
some  cases  lias  almost  wholly  stopped  the  process.  The  steam  prd 
sure  employed  varies  somewhat  with  the  kind  of  ore.  Cedar  woo] 
which  grows  in  abundance  in  this  vicinity,  is  used  as  fuel. 
The  sulphur  as  it  comes  from  the  retort  has  been  analyzed  by  Her 
man  Harms,  State  chemist  of  Utah,  who  reports  the  composition  1 
follows: 
Analysis  of  sulphur  from  retort  "/  Sulphurdale,  Utah. 
Sulphur 99.  7  ! 
Nonvolatile  residue  (silica,  iron  oxide,  etc.) .23 
Free  sulphuric  acid Trace. 
Sulphurous  acid 0 
Arsenic o 
Moisture  at  LOO6  C on 
100. 00 
ORIGIN. 
Several  facts  noted  seem  to  point  clearly  to  the  mode  of  origin  of 
the  sulphur.  The  geologic  relations,  previously  stated,  indicate  thai 
the  deposits  are  on  or  very  near  a  fault  line  and  are  closely  associated 
with  volcanic  rocks.  The  presence  of  a  recently  extinct  volcano  to 
the  wot.  the  flows  from  which  extend  within  about  a  mile  of  the 
sulphur  beds,  suggests  that  the  sulphur  ma\  have  resulted  from  the 
eruptions  (^  this  volcano.  Gas  is  now  escaping  here  in  large  volumes! 
in  some  places  through  vents  suggesl ing  those  supposed  to  have  giveq 
rise  io  the  cylindrical  cores  of  sulphur:  in  other  places  through  thou 
sands  of  small  jets  from  the  porous  beds  of  tuff,  giving  rise  to  the 
genera]  dissemination  of  the  sulphur  through  the  beds.  Wherever 
water  stands  in  the  excavations  the  gas  boils  up  through  it  at  short 
Intervals.  No  sulphur  dioxide  (S02)  was  noted,  but  the  disagreeable 
odor  of  hydrogen  sulphide  (IIS  was  strongly  perceptible.  The 
occurrence  n(  large  quantities  of  hydrogen  sulphide  suggests  that  this 
gas  i-  the  source  of  the  sulphur.  When  it  comes  into  contact  with 
oxygen  in  the  porous  tuff  near  the  surface  it  is  probably  oxidized, 
losing  it>  hydrogen  and  dropping  the  sulphur  as  expressed  by  the 
simple  formula: 
n,s-}<)    no    s. 
The  sulphur  being  a  solid  remains  where  it  is  set  free  in  the  porous  tuff. 
If  this  explanation  is  correct,  continued  oxidation  would  form  a  cer- 
tain amount  of  sulphur  trioxide  (S-r30  =  S03),  which  in  combination 
with  water  forms  sulphuric  acid  (H20  +  S03  =  H2S04).  It  is  a  matter 
of  interest  in  this  connection  to  observe  that  the  water  issuing  from 
the  beds  is  strongly  charged  with  acid,  as  shown  by  the  following 
analysis  made  by  W.  M.  Barr,  of  the  United  States  Geological  Survey: 
