Am.  Jour.  Pharm.  1 
July  1,1872.  j 
Varieties. 
321 
tains  less  than  50  per  cent.,  the  mine  is  abandoned  as  not  worth  work- 
ing; a  yield  of  70  to  80  per  cent,  is  exceptionally  good.  The  raw 
material  is  transported  on  pack  animals  or  wagons  to  the  factory, 
where  it  is  refined  in  two  different  ways.  One  method  is  to  break  it 
up  in  pieces  and  put  it  in  an  iron  kettle  half  full  of  water,  which  is 
then  heated  over  fire  for  an  hour,  the  insoluble  matter  removed  and 
a  fresh  quantity  of  raw  material  added  until  the  solution  is  saturated. 
The  clear  solution  is  run  off  into  crystallizing  vessels,  the  crystals 
collected  when  formed  and  allowed  to  dry  in  the  sacks  in  which  it  is 
shipped.  In  the  second  method,  steam  heat  is  employed ;  the  crude 
material  is  put  in  perforated  iron  baskets  and  suspended  in  boiling 
water,  and  the  process  repeated  until  the  liquor  is  saturated.  The 
salpeter  prepared  in  this  way  contains  less  than  one  per  cent,  of  com- 
mon salt,  while  that  obtained  by  the  former  method  contains  upward 
of  two  per  cent.  Large  quantities  of  iodine  are  annually  reclaimed 
from  the  mother  liquors  of  the  saltpeter  works  of  South  America. — - 
Scientific  American,  April  27,  1872. 
A  Delicate  Test  for  Phenol. — Landolt,  wishing  to  detect  the  presence  of 
phenol  (carbolic  acid)  in  a  well-water  from  the  vicinity  of  a  gas-works,  and 
finding  that  the  ferric  chloride  test  is  only  of  moderate  delicacy,  and  is  inter- 
fered with  even  by  normal  salts,  as  sodium  sulphate,  made  use  of  bromine-water. 
When  used  in  excess,  this  reagent  gives,  even  with  a  solution  of  phenol  in 
43,700  parts  of  water,  an  immediate  bulky  precipitate  of  tribromophenol. 
The  odor  of  phenol  cannot  be  recognized  when  the  solution  contains  less  than 
1  of  phenol  to  2800  of  water ;  and  the  color  developed  by  ferric  chloride  ap- 
pears only  when  there  is  more  than  1  of  phenol  to  2100  of  water.  By  this  test, 
the  presence  of  phenol  may  be  shown  in  500  c.c.  of  urine.  It  may  also  be  used 
quantitatively, — Amer.  Jour.  Science  and  Arts,  May,  1872,  from  Ber.  BerU 
chem.  Ges.,  iv,  770,  Oct.,  1871. 
A  New  Test  for  Arsenic. — Bettendorff*  has  simplified  Hager's  method  of  test- 
ing for  this  substance,  and,  it  would  seem,  has  rendered  it  peculiarly  suitable 
for  testing  pharmaceutical  preparations  for  slight  impurities  from  this  element. 
The  method  of  testing  commercial  sulphuric  acid  for  traces  of  arsenic  will 
give  a  fair  illustration  of  the  author's  process. 
A  small  quantity  of  protochloride  of  tin,  in  a  shallow  dish,  is  covered  with 
pure  hydrochloric  acid  (1*12  sp.  gr.j  until  it  is  dissolved.    To  this  is  added, 
*  Dingler's  Journal,  C  iii,  385, 
21 
