504  Two  New  Allotropic  States  of  Siilphur.{Xm-^\^rm- 
under  atmospheric  pressure  and  in  a  vacuum  being  I  :  6  6.  The 
quantity  of  impure  zinc  dissolved  under  similar  conditions  was  found 
to  undergo  very  little  change. 
In  the  next  series  of  experiments,  the  quantity  of  pure  zinc  dis- 
solved by  the  acid  at  different  temperatures  was  determined.  The 
quantity  dissolved  in  30  minutes  increased  regularly  from  2-1  milli- 
grams at  o°  to  9-3  milligrams  at  980,  but  as  soon  as  ioo°  was 
reached  and  ebullition  commenced  the  quantity  rose  to  122-1  milli- 
grams. This  is  in  full  agreement  with  the  author's  theory,  as  the 
evolution  of  bubbles,  which  start  for  the  most  part  from  the  zinc 
plate,  would  naturally  affect  the  hydrogen  film  and  expose  fresh  sur- 
faces of  the  zinc  to  the  action  of  the  acid.  If  the  temperature  be 
raised  above  ioo°  by  increasing  the  pressure,  the  quantity  of  zinc 
dissolved  is  not  appreciably  more  than  at  980  so  long  as  ebullition 
does  not  take  place.  The  quantity  of  impure  zinc  dissolved  is  not 
appreciably  affected  by  the  ebullition  of  the  liquid. 
The  addition  of  chromic  acid  and  of  hydrogen  peroxide  to  the 
acid  also  causes  a  great  increase  in  the  solubility  of  the  pure  zinc, 
the  former  causing  an  increase  in  the  ratio  175  :  1,  and  the  latter  in 
the  ratio  306  :  I,  a  result  which  is  again  strongly  in  favor  of  the 
author's  theory.  These  oxidizing  agents  do  indeed  also  increase  the 
solubility  of  impure  zinc,  but  to  a  much  smaller  extent,  the  ratio  for 
chromic  acid  being  6  5  :  I,  for  hydrogen  peroxide  3-5  :  I. 
Similar  results  have  been  obtained  with  cadmium,  cobalt,  iron  and 
aluminium.  The  latter,  which  is  as  a  rule  ahaost  insoluble  in  dilute 
acids,  dissolves  readily  in  a  vacuum,  and  also  dissolves  under  similar 
conditions  in  neutral  ferric  chloride  solution,  the  latter  being  reduced 
to  ferrous  chloride  by  the  hydrogen  evolved. 
TWO  NEW  ALLOTROPIC  STATES  OF  SULPHUR. 
Two  new  allotropic  conditions  of  sulphur  have  been  prepared  by 
Engel  in  the  following  way :  two  volumes  of  a  solution  of  hydro- 
chloric acid  containing  from  25  to  30  per  cent,  of  acid,  and  at  a  tem- 
perature of  10°,  are  mixed  with  constant  stirring  with  one  volume 
of  the  same  strength  of  a  solution  of  hyposulphite  of  soda.  Chloride 
of  sodium  is  precipitated  and  hyposulphurous  acid  set  free.  The 
'acid  in  this  condition  possesses  a  sufficient  stability  to  permit  of  its 
being  filtered  without  coloration.  Little  by  little  the  filtered  liquid 
becomes  yellow  and  the  intensity  of  the  coloration  increases,  and  at 
