274 
Note  on  Frozen  Glycerin. 
fAm.  Jour.  Pharm. 
1        June,  1885. 
I  was  aware  that  two  instances  of  the  kind  had  been  observed, 
and  were  commented  on  in  a  foot-note  in  the  U.  S.  Dispensatory,  15th 
edition,  p.  711 ;  bnt,  as  I  had  never  seen  the  substance  in  the  solid 
state,  my  first  impression  was  but  natural.  A  specimen  of  the  mass 
was  removed  from  the  can  and  preserved  in  a  wide-mouthed  bottle ; 
this  was  placed  in  a  refrigerator.  It  was  brought  to  the  college  on 
April  21st,  to  be  shown  at  the  pharmaceutical  meeting  called  for  that 
day,  but  which,  for  lack  of  attendance,  did  not  come  to  order.  On 
that  occasion  more  than  half  of  the  solid  contents  of  the  bottle  melted, 
but  a  re-exposure  to  the  temperature  of  an  ordinary  refrigerator  has 
again  caused  crystallization.  The  crystalline  structure  is  beautifully 
defined,  as  may  be  noted  in  the  bottle  presented,  which  I  have  packed 
in  a  freezing  mixture  to  insure  the  preservation  of  that  form. 
The  melting  point,  roughly  ascertained,  is  between  21  °C.  to  26 °C., 
or  70°F.  to  80°r. 
When  completely  melted  and  exposed  to  the  temperature  of  a  mix- 
ture of  ice  and  salt  for  an  hour,  no  signs  of  "  freezing were  observed. 
Whether  a  longer  period  would  cause  recrystallization  I  am  unable  to 
say. 
If  the  sp.  gr.  were  higher,  it  would  the  more  readily  suggest  that 
a  state  of  almost  complete  dehydration  was  the  most  reasonable  expla- 
nation of  the  phenomenon;  but  here  we  have  '013,  or  '015  less  than 
the  officinal  standard  glycerin,  which  during  my  acquaintance  with  its 
properties  has  not  been  observed  to  "  freeze."  Since  writing  the  above 
an  accurate  determination  of  the  sp.  gr.  of  the  melted  crystals  reveals 
the  fact  that  the  portion  which  actually  solidifies  has  really  a  high  per- 
centage of  glycerin  as  indicated  by  the  sp.  gr.  1*2618  obtained  by  Prof. 
Trimble. 
Aquae  Aromaticse. — Mr.  R.,  in  a  communication  to  the  "Central- 
halle,"  recommends  to  dissolve  15  drops  of  the  best  quality  of  essen- 
tial oil  in  4  Gm.  of  alcohol  (95  per  cent.),  and  to  use  1  drop  of  such  an 
essence  to  10  Gm.  of  distilled  water.  Medicated  waters  prepared  with 
alcohol  soon  turn  sour ;  therefore  a  large  stock  of  them  should  never 
be  kept  on  hand,  but  it  is  more  economical  and  convenient  to  prepare 
them  extemporaneously  as  stated.  Mr.  R.  speaks  very  highly  of  the 
orange-flower  water  prepared  with  such  an  essence,  and  distilled  from 
a  glass  retort. 
