NOTES  ON  PLASMA. 
555 
experience,  1  am  not  a  little  pleased  to  find  plasma  not  only 
talked  about,  written  about,  and  prescribed,  but  also  that  a 
proposition  has  been  made  by  no  less  an  authority  than  Dr.  Red- 
wood to  introduce  it  into  the  next  Pharmacopoeia. 
From  the  date  of  my  paper  (February,  1858)  to  the  present 
moment  I  have  made  no  further  public  allusion  to  the  article ;  I 
may,  perhaps,  then  be  excused  if  I  now  once  more  obtrude  it 
upon  my  fellow-pharmaceutists. 
It  is,  perhaps,  undesirable  that  I  should  follow  every  one  who 
has  expressed  himself  upon  the  matter  ;  in  referring,  however,  to 
the  opinions  and  observations  of  a  few,  I  trust  to  be  understood 
to  imply  no  disrespect  for  the  labors  of  the  rest. 
I  may,  observe,  as  a  general  remark,  that  those  who  have 
written  upon  the  matter  express  opinions  favorable  to  the 
preparation ;  the  objections  to  it  have  usually  been  uttered  in 
conversations  and  discussions  upon  these  more  deliberately 
expressed  opinions.  The  list  of  tangible  objections,  however, 
is  not  large ;  it  amounts  to  no  more  than  two.  These  are 
serious  objections,  I  admit,  if  they  really  exist,  but  they  are  not 
numerous. 
The  first  is,  that  the  preparation  becomes  softer  by  exposure 
to  the  moisture  of  the  air ;  and  the  second,  that  it  is  liable  to  be- 
come mouldy  by  keeping. 
With  regard  to  the  first,  I  think  we  must  admit  that  it  is  a 
difficulty.  I  pointed  it  out  in  my  original  paper,  and  I  do  not 
think  there  is  any  prospect  of  our  being  able  altogether  to  obvi- 
ate it.  We  must  accept  it  as  a  property  of  all  preparations  of 
glycerine,  and  avoid  exposure  to  moisture  as  much  as  possible. 
But  I  have  not  found  this  property  of  much  practical  inconveni- 
ence. I  have  kept  plasma  in  a  common  covered  pot  for  a  long 
time  without  apparent  change.  Here  is  a  sample  kept  in  this 
way  since  December,  1865,  and  it  is  still  of  very  good  con- 
sistence. But  if  the  article  be  really  useful,  there  would  be  no 
more  difficulty  in  preserving  it  in  well-closed  vessels  than  many 
others  about  which  we  have  to  be  specially  careful. 
The  second  alledged  objection  to  plasma  is,  that  it  becomes 
mouldy  by  keeping.  This  statement  is  backed  by  the  authority 
of  names  that  command  respect.    Mr.  Dean  and  Mr.  Squire 
