ON  CAFFEIN. 
225 
Before  concluding  these  remarks,  it  may  be  well  to  suggest 
that  advantage  may  be  taken  of  the  compatibility  of  gum  mez- 
quite  and  subacetate  of  lead  to  use  the  mucilage  of  that  gum  as 
a  vehicle  for  Goulard's  Extract,  in  those  cases  where  it  is  desira- 
ble to  have  the  emollient  and  protective  influence  of  mucilage, 
with  the  astringent  and  sedative  action  of  the  lead  salt.  The 
association  of  mezquite  mucilage  and  subacetate  of  lead,  with  suf- 
ficient glycerin  to  keep  it  from  drying  too  rapidly,  would  be  a 
good  substitute  for  many  of  the  less  elegant  and  efficient  dress- 
ings : — of  course  the  proportion  of  subacetate  should  be  regulated 
by  the  physician  in  applications  to  excoriated  surfaces. 
ON  CAFFEIN. 
By  H.  Leuchsenring. 
Caffein  possessing  decided  physiological  and  therapeutic  pro- 
perties, I  submit  to  the  notice  of  our  profession  a  simple  and 
easy  process  for  obtaining  it. 
A  concentrated  decoction  of  coffee  or  tea,*  (cocoa  or  guarana) 
is  precipitated  by  a  weak  solution  of  acetate  of  lead ;  the  liquor 
is  filtered  and  evaporated  to  dryness  ;  the  residue  is  mixed  with 
fine  sand  and  allowed  to  sublime  by  the  process  of  sublimation 
of  Dr.  Mohr  for  benzoic  acid. 
Caffein  thus  obtained  is  in  prisms,  white,  opaque,  silky  and 
compact,  of  a  bitter  taste,  soluble  in  98  parts  of  water — 97  of 
alcohol  and  in  194  of  ether — fuses  at  170°  Cartier — volatilises 
at  185°.  Its  solution  in  hydrochloric  acid  is  precipitated  white, 
and  in  chloride  of  platinum  yellow,  by  tannic  acid.f 
*  Theobroma  cacoa  or  Paullinia  sorbilis. 
■("[Note  by  theEditok. — This  process  is  the  same  as  that  of  the  Hanoverian 
Pharmacopoeia,  a  notice  of  which  was  published  at  page  472,  vol.  xxv.  of  this 
Journal.  H.  J.  Versmann  (Archiv.  der  Pharm.  lxviii.  p.  148)  gives  a 
process  in  which  5  parts  of  raw  coffee  in  powder  mixed  with  one  part  of 
dry  hydrate  of  lime  is  treated  in  a  displacer  with  alcohol  (sp.  gr.  -863)  until 
exhausted.  The  alcoholic  liquids  are  distilled  to  regain  the  alcohol — the 
fixed  oil  which  floats  on  the  aqueous  residue  separated,  and  the  residue 
evaporated,  till  on  cooling  it  solidifies  by  crystallization.  After  standing  a 
while  the  mother  liquid  is  drained  off — the  crystals  passed  between  paper 
to  remove  the  fixed  oil,  and  aftersolution  in  boiling  water  and  treatment  with 
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