252 
ON  THE  IGNITING  POINT  OF  VAPORS,  ETC. 
Mr.  WooD'said  he  had  frequently  taken  milk  of  sulphur,  but  could  not 
take  precipitated  sulphur. 
Mr.  Martindale  said  the  process  was  first  introduced  in  the  London 
Pharmacopoeia  in  1721,  and  the  preparation  was  there  called  lacsulphuris. 
which  name  had  ever  since  been  retained  for  that  particular  preparation, 
Mr.  Hanbury  thought,  in  the  Pharmacopoeia  in  which  it  was  ordered, 
the  process  was  given  in  ignorance.  He  was  far  from  advocating  the 
use  of  this  calcareous  sulphur,  which  he  considered  an  abomination, 
and  did  not  think  there  could  be  so  much  difficulty  in  introducing  a 
pure  article  as  some  gentlemen  seemed  to  suppose.  In  the  house  in 
which  he  was  a  partner,  there  had  not  been  any  so-called  milk  of  sul- 
phur for  a  long  time.  They  always  used  pure  sulphur,  and  never  found 
any  complaint. 
A  Member  said  when  a  customer  went  to  a  chemist  he  trusted  to  him 
to  supply  him  with  a  pure  article ;  he  did  not  know  the  difference  be- 
tween milk  of  sulphur  and  pure  sulphur. 
The  Chairman  thought  the  public  judged  in  such  matters  very  much 
by  what  they  had  been  accustomed  to  receive,  and  if  they  had  been  used 
to  an  impure  article,  they  would  prefer  it  to  the  genuine. 
Mr.  Morson  said  milk  of  sulphur  was  an  old  preparation,  which  was 
literally  a  mixture  of  sulphur  and  sulphate  of  lime,  and  the  subdivision 
of  the  sulphur  by  this  means  did,  no  doubt,  influence  its  action.  If  any 
one  asks  for  pure  or  precipitated  sulphur,  they  should  get  it;  but  milk 
of  sulphur  was  a  different  thing,  which  they  also  had  a  right  to  get  if 
they  wished  for  it.  He  recommended  them  to  keep  both  articles,  and 
supply  whichever  was  wanted. — Lond.  Pharm.  Journ.,  Feb.,  1869. 
N  THE  IGNITING  POINT  OF  THE  YAPORS  OF  SOME  COM- 
MERCIAL PRODUCTS.* 
By  W.  R.  Hutton,  Esq. 
It  is  a  well-known  fact  that  many  commercial  products  at  cer- 
tain temperatures  give  off  an  inflammable  vapor,  and  my  object 
in  bringing  this  paper  before  the  Chemical  Section  is  to  give  the 
results  of  comparative  trials  of  the  igniting  points  of  a  few  of 
the  leading  articles  of  commerce,  and  also  to  explain  the  method 
employed  by  me  in  testing,  which  is  very  simple  and  sufficiently 
accurate. 
In  commerce  there  are  several  substances  which,  at  the  ordi- 
nary temperature  of  the  atmosphere,  are  sufficiently  volatile  to 
emit  enough  vapor  to  form,  with  atmospheric  air,  an  explosive 
mixture.    There  are  m^ny  others  which  do  not  volatilize  at 
*  Read  before  the  Chemical  Section  of  the  Glasgow  Philosophical 
Society,  Dec.  21st,  1868. 
