Novembers"}  Properties  and  Uses  of  Formaldehyde.  619 
may  be  given  in  doses  up  to  90  grains  as  an  intestinal  antiseptic,  its 
action  depending  on  small  quantities  of  formaldehyde  that  are  con- 
tinuously liberated ;  and  this  is  put  forward  as  one  proof  of  the 
harmless  nature  of  the  antiseptic.  Dr.  Rideal  is  said  to  have  taken 
a  considerable  quantity  of  a  I  per  cent,  solution  without  experienc- 
ing any  ill  effects. 
Formaldehyde  ranks  high  as  a  deodorant.  Either  as  vapor  or  in 
solution  it  almost  instantly  removes  the  putrid  odor  of  decomposing 
animal  or  vegetable  matter,  combining  with  sulphuretted  hydrogen, 
mercaptan,  ammonia  and  ammonia  bases  generally  to  form  inodor- 
ous compounds.  With  ammonia  it  gives  hexamethyleneamine. 
Putrid  meat,  broth,  urine,  faeces,  etc.,  are  immediately  deodorized 
when  treated  with  a  little  of  the  40  per  cent,  solution. 
The  vapors  given  off  by  the  solution  are  extremely  irritating  to 
the  eyes  and  the  mucous  membrane  of  the  nose  and  throat,  so 
that  care  should  be  taken  when  handling  the  solution  not  to  spill 
any  on  the  hands  or  skin,  as  it  is  found  to  have  a  similar  effect  to 
strong  carbolic  acid.  No  pain  is  felt  at  the  moment,  but  afterwards 
the  skin  becomes  quite  insensitive,  and  very  rough  and  white 
wherever  the  liquid  has  been  in  contact  with  it. 
Gelatin  exposed  to  formaldehyde  vapor  becomes  insoluble  even 
in  hot  water,  and  animal  tissues  generally  are  hardened  in  a  remark- 
able manner.  This  property  is  turned  to  account  in  the  rapid 
hardening  of  tissues  for  microscopical  examination,  and  in  photog- 
raphy ;  Dr.  C.  L.  Schleich  has  also  prepared  from  the  formalized 
gelatin  an  antiseptic  dusting  powder  for  wounds.  Dr.  Schleich  dis- 
solves gelatin  in  water,  adds  25  minims  of"  formalin  "  to  the  pound 
of  gelatin,  and  dries  and  powders  the  product.  This  powder,  in 
contact  with  healthy  or  inflamed  tissue,  disengages  formaldehyde 
vapor,  thus  maintaining  an  antiseptic  atmosphere  around  the  wound. 
Necrotic  tissue  or  masses  of  dried  secretion  may  prevent  contact 
between  the  powder  and  the  wound,  in  which  case  recourse  is  had 
to  a  weak  hydrochloric  solution  of  pepsin,  which  liberates  formal- 
dehyde from  the  powder  equally  as  well  as  the  living  tissue. 
As  a  hardening  agent  in  microscopy,  and  for  the  preservation  of 
vegetable  structures,  formaldehyde  solution  promises  to  be  of  the 
greatest  service.  Mr.  E.  M.  Holmes,  F.L.S.,  read  an  interesting 
paper  on  this  subject  some  months  since,  and  his  experience  con- 
firms the  statements  that  have  been  made  as  to  the  advantages  of 
