210 
Use  of  Boric  Acid  as  a  Disinfectant.  { Amx^ur- ^J™- 
threads  to  each  organism).  Each  thread  was  then  placed  in  a  satu- 
rated solution  of  boric  acid  and  exposed,  respectively,  5,  10,  15,  20, 
25,  30,  35,  40,  45  and  50  minutes,  after  which  each  thread  was  placed 
in  a  tube  of  sterile  plain  broth  and  incubated  at  370  C.  for  one 
week. 
Controls  were  made  for  each  organism  by  placing  the  dried 
thread  (from  the  suspension)  directly  without  exposure  to  boric 
acid,  into  tubes  of  plain  broth. 
A  check  was  also  made  on  the  boric  acid  by  placing  one  Cc. 
boric  acid  in  a  tube  of  plain  broth  and  incubating  at  37°  C.  The 
results  of  this  experiment  are  shown  in  Table  III. 
Even  under  these  conditions,  boric  acid  exhibited  very  little  in- 
hibitive  effect  on  bacteria.  In  this  experiment  the  entire  saturated 
solution  was  available  for  action  toward  the  bacteria.  A  saturated 
solution  of  the  boric  acid  when  allowed  to  act  on  the  organisms  for 
50  minutes  did  not  kill  them.  Bacillus  typhosus  was  killed  by  35 
minutes'  exposure  to  the  saturated  boric  acid. 
An  attempt  was  made  to  determine  whether  boric  acid,  acting 
as  an  antiseptic,  would  effect  yeast  fermentations.  It  seemed  to 
possess  no  consistent  action  since  in  many  cases  more  gas  was 
formed  after  exposure  to  boric  acid  than  before.  Under  the  con- 
ditions of  this  experiment  the  boric  acid  seemed  to  have  no  antiseptic 
activity  in  reducing  the  zymogenic  activity  of  the  yeast. 
Conclusions. — A  prominent  writer  on  preventive  medicine  has 
stated  that  boric  acid  was  a  "  camouflage  "  disinfectant.  Such  seems 
to  be  the  result  of  this  short  study.  The  use  of  this  reagent  in 
those  cases  where  disinfection  is  absolutely  essential,  should  be  dis- 
continued. It  seems  probable  that  many  of  the  salts  of  boric  acid 
may  have  as  limited  a  disinfecting  power  as  the  acid  itself.  The 
statements  of  the  vendors  are  possibly  misleading. 
