Am.  Jour.  Pharm."! 
December,  1903.  J 
Progress  in  Pharmacy. 
577 
Although  the  experiments  are  still  being  carried  on,  Dr.  Wiley, 
under  whose  personal  supervision  the  observations  are  being  made, 
recently  expressed  the  opinion  that,  whether  these  food  preservatives 
are  dangerous  or  not,  in  the  quantities  usually  used,  all  food  prod- 
ucts containing  them  should  be  clearly  and  distinctly  labelled  as  to 
the  kind  and  quantity  of  chemical  substances  that  have  been  added 
to  preserve  them. 
Enzyme  Fermentation. — Buchner's  interesting  and  valuable  dis- 
covery of  the  true  cause  of  fermentation  is  being  exploited  in  a 
practical  way  in  Germany,  where  large  quantities  of  yeast  are  to  be 
found  as  by-products  in  the  various  industries  where  fermentation 
is  a  factor.  The  products,  as  made  at  the  present  time,  are  intended 
either  as  a  substitute  for  meat  extracts,  or  as  antiseptics  in  medicine. 
A  typical  product  of  the  latter  class  is  Zymin.  This  is  a  sterilized 
yeast  made  by  introducing  the  washed  and  partially  dried  yeast  into 
acetone,  subsequently  drying  at  a  low  temperature,  to  prevent  the 
coagulation  of  the  contained  albumins.  The  resulting  product  is  a 
perfectly  sterile,  dry  white  powder,  that  retains  the  fermenting  prop- 
erty of  yeast  for  a  considerable  length  of  time. 
A  somewhat  similar  preparation  is  being  made  in  France,  by  dry- 
ing the  washed  yeast  at  low  temperatures.  This  latter  preparation 
is  said  to  contain  appreciable  quantities  of  living  yeast  cells,  which 
for  medicinal  use  are  not  desirable.  (R.  Rapp,  Phar.  Centralh.,  1 903, 
p.  224.) 
Of  the  extracts  of  yeast,  consisting  chiefly  of  vegetable  albumins, 
the  following  are  typical  preparations : 
Ovos — For  this  preparation,  beer  yeast  is  carefully  washed,  to 
free  it  from  the  bitter  of  hops ;  the  yeast  is  then  pressed  and  sub- 
jected to  a  steam-bath,  which  ruptures  the  membranous  cell  walls  and 
allows  the  contained  liquid  to  escape.  The  liberated  cell  contents 
are  subsequently  separated  from  the  cell  walls  by  pressure  and  filtra- 
tion. The  resulting  liquid  is  evaporated  to  the  consistency  of  a 
thick  extract.  This  product  is  soluble  in  cold  water,  the  aqueous 
solution  has  an  acid  reaction  and  responds  to  the  usual  tests  for  albu- 
min. 
Siris,  Yeast  Extract,  is  prepared  by  an  ingenious  process  sug- 
gested by  Buchner:  The  purified  and  pressed  yeast  is  put  into  glass 
vessels  and  these  are  attached  to  an  air-pump ;  a  partial  vacuum  is 
then  produced,  and  the  yeast  allowed  to  stand  for  twenty-four  hours- 
