c     set up for aq+ky+zo+an+H2O

      implicit   real   (a-z)   
20    write (*,*) 'enter xgr, xpy, xalm, xan, xab, nalzo, nfezo'   
      read  (*,*)   xgr,  xpy, xal, xan, xab, nalzo, nfezo  

      xan = xan / (xan+xab)
      ztot = nalzo + nfezo
      nalzo = nalzo * 3. / ztot
      nfezo = nfezo * 3. / ztot
      xzo = 1. - nfezo

      write (*,*) ' xan and xzo ', xan, xzo
c                              T's for endmember points
      t1 = 900.
      t2 = 950.
c                              endmember points for gr:
      pg1 = 12562.
      pg2 = 13698.
c                              endmember points for zo:
      pz1 = 8037.7
      pz2 = 9142.
c
      sg = (pg2-pg1) / (t2-t1)
      sz = (pz2-pz1) / (t2-t1)
      db= (pg1 - pz1) + t1 * (sz - sg)
      ds= sg - sz
      dvz = 7.81
      dvg = -6.26

      xt  =   xgr + xpy + xal  
      xgr =  xgr  /   xt  
      xpy =   xpy  /  xt   
      xal =   xal  /   xt  
      r   =   8.314  
      x1   =  xpy   /  (xpy+xal)   
      x2  =  1.  -  x1 
      b  =  x1*(-11.205)  +  x2  * ( -8.293)  
      c  =  x1*(-.512) +  x2  * ( -1.482 ) 
      d  =  x1 *  (-.418)  +  x2  *  (-.480)  
      e =  x1 *  .94  + x2  *  .914 
      f  =  x1 *  0.083  +  x2 *  0.066  
      x =  1.-  xgr   
      z  =   (x   -  e)/   f   
      vgr = -c * x*x +d*(1+z*x/f) *  exp(z**2/(-2.))  
      vgr  =  0.1  *  vgr  
10    write (*,*)  'enter  p,  t, ah2o'   
      read  (*,*)  p, t, aw   
      if  (p.eq.0.0)  goto 20
      aan = xan*(1.+xan)**2/4.*exp((1-xan)**2/r/t*   
     *            4.184*(2050.+9392.*xan))             
      wg = 3.*4.184*(3300.- 1.5*t) 
      agr  = xgr**3 *  exp ( wg  / r /t *(xpy**2  + xpy*xal)  ) 
      write  (*,*) 'aan,  agr, vgr  ', aan, agr,   vgr
      kx    =    (xgr/xan)**3    
      lkx    =    log   (kx)    
      write  (*,*)  'kx,  lkx  ',kx,  lkx  
      lkv   =  p * vgr  /  r  /  t   
      kv  =   exp  (lkv)   
      ka   =  agr  / aan**3   
      lka   =  log(ka)

      dp = t * ds + db
      kg = ka * kv

      kz = aw*aan**4 / xzo**2

      dpz = r*t*log(kz)/dvz

      dpg = r*t*log(kg)/dvg

      write (*,*) 'sg, sz = ',sg,sz
      write (*,*) 'pg0 = ',sg*(t-t1) + pg1
      write (*,*) 'pz0 = ',sz*(t-t1) + pz1
      write (*,*) 'pg  = ',sg*(t-t1) + pg1 - dpg
      write (*,*) 'pz  = ',sz*(t-t1) + pz1 - dpz
      write (*,*) 'dp  = ',sg*(t-t1) + pg1 - dpg-sz*(t-t1)-pz1+dpz
      write (*,*) 
      write (*,*)  'kv,  lkv ',kv, lkv  
      write  (*,*)  'ka, lka',ka,lka  
      write (*,*) 'k, lk',ka*kv,lka+lkv
      goto 10 
99    end