566  Gleanings  from  the  German  Journals.      {Am'^oZ  im&Tm' 
Carbolic  Acid  yields,  after  an  evanescent  brown-red  coloration,  a  deep 
blue-green  solution,  on  standing  for  a  time,  or  more  quickly  upon  heat- 
ing, changing  to  a  pure  blue.  By  the  addition  of  an  equal  volume  of 
water  a  blue  or  violet-red  is  obtained  ;  if  a  portion  of  this  diluted  solu- 
tion is  agitated  with  ether,  the  latter  will  be  colored  yellow,  and  on 
evaporation  and  dissolving  the  residue  in  alcohol  the  addition  of  a  sin- 
gle drop  of  an  alkaline  hydrate  solution  will  give  a  blue  color.  The 
blue  color  may  also  be  produced  by  pouring  the  diluted  solution  into 
an  alkaline  hydrate  solution.  Working  carefully  one  drop  of  a  solu- 
tion (1  :  1000)  gives  a  decided  color. 
Thymol  gives  about  the  same  colors,  with  these  differences  :  The 
blue  color  is  more  brilliant  and  on  dilution  the  coloring  matter  sepa- 
rates in  flakes ;  by  agitation  with  ether  the  color  is  completely  ex- 
tracted, coloring  the  ether  a  bluish-red. 
Resorcin  forms  a  deep  blue  solution,  on  addition  of  water  a  red- 
brown  precipitate;  agitated  with  ether  the  latter  is  colored  yellow,, 
leaving  upon  evaporation  a  red-brown  residue  in  reflected  light  pos- 
sessing a  green  metallic  lustre ;  this  residue,  dissolved  in  alcohol,  on 
addition  of  an  alkaline  hydrate,-  form  s  a  violet  solution  with  a  beauti- 
ful brick-red  fluorescence.  If  the  original  test  be  diluted  and  poured 
into  an  excess  of  alkali,  the  violet  solution  and  red  fluorescence  can 
also  be  produced,  and  by  agitation  with  ether-alcohol  (1:1)  the 
fluorescent  principle  will  be  found  in  the  ethereal  solution,  while  the 
aqueous  solution  will  be  of  a  pure  blue  color.  This  last  test  slightly 
modified  serves  as  a  delicate  test  for 
Nitric  or  Nitrous  Acid. — To  the  10-15  drops  of  strong  sul- 
phuric one  drop  of  the  solution  containing  either  of  the  above 
acids  is  added  (if  an  insoluble  salt  is  to  be  tested  it  must  be  rubbed 
up  with  a  little  water  and  one  drop  of  the  mixture  taken),  and,  if 
possible,  upon  same  spot  where  the  drop  was  placed  a  few 
crystals  of  resorcin  are  dropped ;  if  the  quantity  of  the  nitrate 
or  nitrite  was  very  small,  instead  of  a  blue,  a  brown-red  color  may  be 
produced.  The  mixture  is  after  a  few  minutes  diluted  with  2  cc. 
water  and,  after  cooling,  poured  into  an  excess  of  sodium  hydrate 
solution  (if  a  precipitate  of  sulphate  is  obtained  this  must  be  redis- 
solved  by  addition  of  water) ;  again  allowing  to  cool,  the  solution  is 
gently  agitated  with  ether-alcohol,  when  the  brick-red  fluorescence  will 
be  found  in  the  ethereal  layer.  This  test  succeeds  with  one  drop  of  a 
solution  of  sodium  nitrate  (1  :  20,000)  or  with  potassium  nitrite 
(1  :  100,000).— Pharm.  Ztg.,  1889,  560. 
