122 
A  Carboy  Rocker. 
( Am.  Jour.  Fharm. 
\      March,  1891. 
of  two  fluidounces  to  the  pint  greatly  increases  the  therapeutical 
value  of  this  preparation. 
Ammonium  Carbonate.— Therapeutists  agree  that  the  diffusible 
stimulant  action  of  ammonium  carbonate  is  best  represented  in  the 
hard  clearly-crystalline  variety,  and  that  the  effloresced  product  is 
for  practical  purposes  therapeutically  valueless  by  comparison. 
This  is  why  many  physicians  in  their  prescriptions  specify  the 
<f  clear  "  or  "  crystalline  "  variety.  They  have  found  the  effloresced 
powder  valueless. 
Why  ammonium  carbonate  effloresces  on  exposure  to  air  is  easy 
of  explanation  when  we  remember  its  chemical  composition  of  acid 
carbonate  and  carbamate — a  dehydrated  normal  carbonate — and  that 
the  latter  readily  absorbs  water  and  carbonic  acid  gas  (from  the  air) 
to  become  an  acid  carbonate. 
How  best  to  prevent  this  change  has  always  been  a  most  difficult 
question.  For  this  purpose  I  have  been  using  for  the  last  five  or 
six  months  an  expedient  which  has  answered  admirably.  It  con- 
sists simply  in  placing  medium-sized  lumps  of  the  salt  in  a  museum 
or  fruit  jar  (glass  top),  preferably  upon  a  porcelain  or  glass  support, 
to  keep  them  from*  touching  the  bottom  of  the  container,  and  then 
adding  a  small  quantity  of  stronger  ammonia  water  and  closing. 
The  ammonia  gas  neutralizes  the  carbonic  acid  gas  in  the  air  of  the 
container,  and  the  salt  remains  hard  and  densely  crystalline.  I  here 
present  for  inspection  some  ammonium  carbonate  over  four  months 
old  preserved  by  this  method. 
A  CARBOY  ROCKER. 
By  J.  F.  Stevenson. 
Read  at  the  Pharmaceutical  Meeting  of  the  Philadelphia  College  of  Pharmacy,  Feb.  17. 
Having  for  many  years  felt  the  necessity  for  a  better  means  of 
supporting  a  carboy  while  pouring  a  liquid  from  it,  it  occurred 
to  the  writer  to  adopt  a  method  or  principle  which  ' had  not  pre- 
viously been  used.  The  methods  usually  employed  depend  upon 
the  suspension  of  the  carboy,  upon  opposite  sides,  at  a  point 
slightly  above  the  centre  of  gravity  and  carboy  cradles,  trunnions, 
and  other  means  have  been  used  for  the  purpose  of  carrying  out 
this  principle. 
These  methods  have  not  produced  results  which  are  thoroughly 
