Am'FeTis^2arm"}  Temperature  and  Digestive  Ferments.  87 
This  is  a  branch  of  research  which  few  pharmacists  can  take  up, 
but,  fortunately,  the  results  so  far  obtained  are  sufficiently  specific 
to  permit  a  general  rule  to  be  drawn,  which  is,  that  in  cases  where 
solutions  become  infected  with  micro-organic  life,  the  water  used  as 
the  solvent  is  most  probably  the  source  of  the  infection.  Not  only 
should  distilled  water  be  boiled,  but  the  containers  for  it  should  be 
frequently  cleaned  out  thoroughly.  There  are  many  slight  but 
annoying  changes  in  pharmaceutical  products  which  might  be  obvi- 
ated by  the  exercise  of  more  initial  care'  to  exclude  micro-organ- 
isms.— The  Chemist  and  Druggist,  Jan.  2,  1892,  p.  18. 
INFLUENCE  OF  TEMPERATURE  ON  DIGESTIVE 
FERMENTS.1 
By  E.  Biernacki. 
Digestive  ferments  require  for  their  efficient  action  a  certain 
reaction  and  a  suitable  temperature.  The  optimum  temperature  is 
39-400;  that  is,  a  little  over  that  of  the  body.  Higher  temperatures 
destroy  the  ferment,  and  the  present  research  is  occupied  with  the 
determination  of  the  temperature  necessary  for  this  latter  purpose. 
The  first  ferment  investigated  was  trypsin,  and  it  was  found  that 
450  C.  markedly  lessens  its  activity,  and  exposure  for  five  minutes 
to  500  destroys  it  altogether.  The  specimens  of  trypsin  employed 
were  some  pure,  some  impure,  and  certain  exceptions  to  the  above- 
stated  rule  were  noted.  It  being  very  improbable  that  various 
trypsins  differ  in  this  particular,  in  virtue  of  their  inherent  characters, 
experiments  were  instituted  to  determine  the  factor  that  caused  the 
difference.  It  was  found  that  small  admixtures  with  certain  salts 
had  the  power  of  increasing  the  resistance  of  the  ferment  to  tem- 
perature; the  activity  of  the  ferment  was  often  lessened  by  the 
salt  (although  this  was  more  marked  in  the  case  of  pepsin),  but  the 
optimum  temperature  was  500;  550  lessened,  and  6o°  destroyed, 
the  activity  of  the  ferment.  The  salts  which  acted  thus  were 
ammonium  sulphate  (a  salt  used  in  the  preparation  of  some  speci- 
mens of  ferment  used  in  the  preliminary  experiments),  ammonium 
chloride,  phosphate  and  nitrate,  and  sodium  chloride.  If  mixtures 
of  two  or  more  of  these  salts  were  used,  the  effect  was  more  marked 
still. 
Certain  salts  (ammonium  carbonate  and    oxalate,  magnesium 
1  Zeit.  Biol.,  28,  49-71  ;  Jour.  Chem.  Soc,  1891,  p.  1271. 
