VARIETIES. 
471 
over  an  area  of  50  acres.  The  soil  of  this  Mammoth  Grove  is  moist  and 
rich. — American  Journal  of  Science  and  Arts.  > 
Mode  of  Using  Bi-sulphaie  of  Soda  as  a  Substitute  for  Cream  of  Tartar 
and  Alum. — The  use  of  this  substitute  in  the  dyeing  of  woollen  goods  is 
becoming  more  general  every  day,  in  consequence  of  the  saving  of  nearly 
one  hundred  per  cent,  effected  by  it.  The  colors  in  the  preparations  of 
which  it  has  hitherto  been  employed  are  chrome-black,  chrome  brown,  grey, 
all  fancy  colors,  green,  carmine,  blue.  A  decoction  made  in  four  pounds  of 
the  bi-sulphate  has  the  same  effect  as  four  pounds  of  alum  and  two  pounds 
of  tartar ;  in  the  dyeing  of  some  colors  some  alum  is,  however,  still  em- 
ployed. For  every  fifty  pounds  of  wool  to  be  dyed  of  a  chrome-black,  one 
pound  of  chromate  of  potash  and  one-half  pound  of  the  substitute  are  re- 
quired. The  wool  is  to  be  introduced  at  a  temperature  of  190°  F.,  then 
boiled  for  fifty  minutes,  and  dyed  in  a  fresh  bath  of  Brazil  wood,  con- 
taining, according  to  the  shade,  one-quarter  to  one-half  pound  of  the  dye- 
wood.  To  dye  the  same  quantity  of  wool  of  a  chrome-brown,  one  pound  of 
chromate  of  potash,  one  and  one-half  pounds  of  substitute  and  half  a  pound 
of  alum  are  employed.  The  wool  is  boiled  for  one  hour,  and  then  dyed  in 
a  bath  of  logwood  ;  or  for  a  yellowish  brown  and  bronze  shade,  in  a  bath 
composed  of  fustic,  Brazil  wood  and  logwood  in  certain  proportions.  In 
the  dyeing  of  green  some  add  alum  to  the  substitute,  and  throw  the  substi- 
tute, in  the  proportion  of  half  a  pound  to  ten  pounds  of  wool,  directly  into 
the  dye-bath,  omitting  altogether  the  previous  boiling. — Deutsche  Muster- 
zeitung,  No.  6,  1853. 
Method  of  Communicating  a  Dull  Black  Color  to  Brass. — According  to 
M.  Leykauf,  a  dull  black  color,  such  as  is  frequently  employed  for  optical 
instruments,  may  be  given  to  brass,  by  first  carefully  rubbing  the  object 
with  tripoli,  then  washing  it  with  a  very  dilute  solution  of  a  mixture  of 
one  part  of  neutral  nitrate  of  tin  and  two  parts  of  chloride  of  gold,  and 
then  wiping  off  the  excess  of  liquid,  after  the  lapse  of  ten  minutes,  with  a 
wet  cloth.  If  there  has  been  no  excess  of  acid,  the  surface  of  the  metal 
will  have  assumed  a  dark  black  color.  The  neutral  nitrate  of  tin  may  be 
prepared  by  decomposing  the  perchloride  with  ammonia,  and  dissolving 
the  precipitated  oxide  thus  obtained  in  nitric  acid. — Le  Technologiste. 
On  the  Detection  of  Strychnine  in  Saccharine  Powders.  By  A.  Vogel, 
Jun. — Otto  has  recommended  bichromate  of  potash  as  a  test  for  strychnine. 
The  substance  to  be  tested  is  mixed  with  the  finely-powdered  salt,  and  then 
moistened  with  sulphuric  acid  ;  a  dark  violet  color  is  produced.  Brieger 
states  that  strychnine  mixed  with  sugar  cannot  be  discovered  in  this  way. 
The  author  says  that  in  this  case  the  substance  to  be  tested  must  first  be 
moistened  with  sulphuric  acid,  and  the  salt  afterwards  added  to  it.  By 
adopting  this  plan,  moreover,  the  reaction  is  not  prevented  either  by  qui- 
nine, cinchonine,  starch  or  dextrine. — Buchner's  JSJeus  Repert.,  ii.  p.  560. 
