Amjiiy,ri8?oharm'}  Medicinal  Gelatins.  357 
The  350  cc.  filtered  from  the  sodium  hydrogen  sulphite  com- 
pounds yielded  (1)  75  cc.  of  a  light  oil,  boiling  at  1770,  and  having 
a  pleasant,  citrene-like  odor;  this  was  analyzed  and  its  vapof- 
density  determined,  the  results  indicating  that  it  was  an  impure 
terpene  ;  (2)  120  cc.  of  a  thicker  oil,  of  rose-like  odor,  boiling  at 
222-2240,  and  of  sp.  gr.  =  0  8741  at  26-5°,  which  appeared  to  be 
citronellyl  alcohol  ;  (3)  IOO  cc.  boiling  above  2400,  dark  brown, 
viscid,  and  having  a  peculiar  odor. 
The  residual  500  cc.  of  the  original  oil,  not  readily  volatile  in 
steam,  was  treated  with  sodium  hydrogen  sulphite,  and  yielded 
about  10  cc.  of  citronellic  aldehyde,  and  a  residual  475  cc.  which, 
when  distilled,  behaved  like  the  residue  from  the  other  sulphite 
precipitate,  but  yields  a  much  larger  amount  of  high-boiling  pro- 
ducts, which  oxidize  readily  and  are  difficult  to  treat.  Citronella  oil 
therefore  contains  citronellic  aldehyde  and  alcohol,  together  with  a 
terpene  and  oils  boiling  above  2400.  The  study  of  these  oils  is  to 
be  continued. 
ON  MEDICINAL  GELATINS.1 
By  Dr.  Unna. 
These  preparations  are  indicated  in  superficial  inflammatory 
affections  when  the  skin  is  swollen,  wet  and  itchy.  Very  high 
temperatures  and  profuse  sweating  forbid  their  use.  For  a  general 
basis  the.  following  formula  is  given — the  figures  within  parentheses 
being  taken  when  a  hard  zinc  gelatin  is  wanted. 
E — Zinc  oxide,  ,   15  (10) 
Gelatin,   »   15  (30) 
Glycerin,  *   25  (30) 
Water,   45  (30) 
In  adding  other  drugs,  the  following  directions  may  be  useful : 
(1)  Cerussa,  iodide  of  lead,  white  precipitate,  sulphur,  iodoform, 
chrysarobin  in  fine  powder  may  be  mixed  in  any  proportion  required. 
A  proportion  of  five  to  ten  per  cent,  added  to  soft  zinc  gelatin  is 
recommended. 
(2)  Carbolic  and  salicylic  acid,  resorcin,  naphthol,  creasote  and  sul- 
phide of  potassium  may  be  added  to  the  hard  gelatin  basis  in  any 
proportion  up  to  ten  per  cent. 
1  Deutsch.  med.  Zeit.}  Nov.  4,  1889.  Reprinted  from  The  Medical  Chronicle, 
March,  1890,  p.  508. 
