Am.  Jour.  Pharm.] 
May,  T883.  j 
Practical  Notes. 
273 
keeps  unaltered  for  a  long  time.  By  further  concentration  in  the  water 
bath  it  may  be  obtained  of  double  or  triple  the  strength  recommended 
aho\e.~BuU.  Gen.  de  Ther.,  1883,  March  15,  p.  214. 
Caustic  Pencils  of  Sulphate  of  Zinc  are  best  prepared,  according  to 
G.  Vulpius,  by  melting  in  a  small  porcelain  capsule,  the  crystallized 
salt  in  its  water  of  crystallization  and  pouring  the  fused  mass  rapidly 
into  conical  moulds  made  of  waxed  paper.  Ordinary  paper  is  unsuit- 
able for  this  purpose,  since  it  becomes  firmly  attached  to  the  pencil. — 
Phar.  ZeUung,  1883,  W.  17. 
Preparation  of  Pyroxylin. — G.  Wolf  recommends  the  following  pro- 
cess which  yields  with  ether-alcohol  a  perfectly  clear  and  colorless 
solution :  20  parts  of  crystallized  potassium  nitrate  are  triturated  in 
a  mortar,  36  parts  of  a  sulphuric  acid  sp.  gr.  1*84  are  added,  and  when 
the  mixture  has  cooled  one  part  of  cotton  is  incorporated  with  the 
pestle  so  as  to  be  uniformly  impregnated ;  after  ten  minutes  the  cotton 
is  placed  upon  a  laterally  preforated  funnel,  this  is  dipped  into  water 
and  the  water  is  removed  until  it  ceases  to  acquire  an  acid  reaction. 
J.  Bienert  operates  with  a  mixture  of  6  fluid  ounces  each  of  sul- 
phuric acid  sp.  gr.  1*84,  and  nitric  acid  sp.  gr.  1*41  to  1*42 ;  when  the 
mixture  has  cooled  to  between  20°  and  25°  C.,  6  or  not  more  than  7 
drachms  of  clean  cotton  are  introduced  and  the  mixture,  which  is  stirred 
once  a  day,  is  set  aside  from  five  to  eight  days  at  a  temperature  of  15° 
to  20°  F.  The  sufficient  nitration  is  observed  by  the  change  of  the 
parchment-like  appearance  of  the  cotton,  and  by  its  becoming  soft  again, 
but  it  is  advisable  to  ascertain  its  solubility  from  a  sample  taken.  This 
gun  cotton  gives  a  strong  cuticle  and  its  solution  in  ether-alcohol  is 
not  precipitated  by  ether. — Phar.  Zeitschr.  Russl.,  1883,  p.  4. 
Preparation  of  Asparagin. — A  precipitant  for  asparagin  has  hitherto 
been  unknown.  E.  Schulze  recommends  mercuric  nitrate  which  causes 
a  white  precipitate  in  aqueous  solutions  of  asparagin,  and  this  princi- 
ple is  liberated  on  decomposing  the  precipitate  with  sulphydric  acid. 
This  behavior  is  serviceable  for  the  preparation  of  asparagin  from 
vegetable  extracts. — Berichte,  1882,  p.  2855. 
Purification  of  Storax. — Benzol  used  for  this  purpose  has  many  dis- 
advantages, such  as  inflammability  of  the  vapors,  its  disagreeable  odor, 
the  high  temperature  at  which  it  volatilizes  completely,  and  its  yel- 
low color  as  frequently  found  in  commerce.  Schlickum  proceeds  as 
follows :    100  parts  of  storax  are  gently  heated,  10  parts  of  alcohol 
18 
