Am.  Jour.  Pharm. 
Sept.,  1918. 
Current  Literature. 
673 
CURRENT  LITERATURE. 
SCIENTIFIC  AND  TECHNICAL  ABSTRACTS. 
USE  OF  TEXTILE  FIBERS  IN  MICROSCOPIC  QUALITATIVE 
<    CHEMICAL  ANALYSIS. 
The  Detection  of  Boron  by  Means  of  Turmeric  Viscose 
Silk  Fibers. — To  obtain  the  characteristic  blue  color  with  turmeric 
by  the  addition  of  alkali  after  drying  down  with  boric  acid,  certain 
difficulties  are  encountered  with  ordinary  turmeric  paper,  and  the 
most  usual  result  is  a  greenish-black  coloration.  The  difficulty  may 
be  overcome  by  using  individual  fibers,  instead  of  paper,  and  ob- 
serving the  reaction  microscopically.  For  dyeing  the  fibers,  a  50 
per  cent,  alcoholic  alkaline  solution  is  made  by  boiling  20  Gm.  of 
powdered  turmeric  with  50  Cc.  of  alcohol,  filtering  and  adding  an 
equal  volume  of  water  and  0.5  to  1.0  Cc.  of  10  per  cent,  sodium 
hydroxide.  The  fibers  are  steeped  in  this  solution,  which  is  then 
evaporated  on  the  water-bath  to  a  syrup.  The  fibers  are  then  quickly 
dipped  in  95  per  cent,  alcohol,  pressed  between  filter-paper,  dipped 
in  dilute  sulphuric  acid,  washed  and  dried.  Care  must  be  taken  to 
avoid  the  presence  of  unabsorbed  turmeric,  since  this  interfers  with 
the  formation  of  the  blue  color.  The  delicacy  and  success  of  the 
test  are  largely  influenced  by  the  nature  of  the  fiber  employed.  Vis- 
cose silk  gives  by  far  the  best  color  reaction,  and  flax  comes  next, 
but  is  not  nearly  so  satisfactory.  For  performing  the  test,  a  drop  of 
the  solution  containing  boron  is  placed  on  a  microscope  slide,  and 
acidified  with  dilute  hydrochloric  acid  to  decompose  borates.  A 
turmeric  fiber  about  5  Mm.  long  is  placed  in  the  drop,  which  is  al- 
lowed to  evaporate  completely  to  dryness,  either  spontaneously  or 
by  very  gentle  warming.  The  slide  is  cooled  and  the  fiber  examined 
under  the  microscope ;  a  rose  or  violet-rose  color  indicates  boron, 
and  when  a  drop  of  1  per  cent,  sodium  hydroxide  solution  is  placed 
on  the  fiber  the  color  changes  to  Prussian  blue,  which  gradually 
turns  to  violet.  Too  high  a  temperature  in  evaporation,  failure  to 
carry  it  to  complete  dryness,  and  too  strong  a  solution  of  soda,  inter- 
fere with  the  success  of  the  test.  The  presence  of  hygroscopic  salts 
is  objectionable,  since  they  prevent  the  complete  drying  of  the  fiber; 
large  amounts  of  free  phosphoric  or  silicic  acid  also  introduce  dif- 
