A.m.  Jour.  Pharm. 
Feb.,  1886. 
Heeren's  Milk-Tester. 
83 
dried  together  in  the  presence  of  moisture  they  have  much  less  cohesion 
with  each  other  than  when  the  reverse  is  the  case.  A  sample,  as  C 
No.  4,  "Creta  Praeparata,"  made  from  the  precipitated  carbonate,  is 
shown.    You  will  note  its  friability. 
It  will  thus  be  readily  seen,  that  this  industry  has  rapidly  assumed 
much  greater  importance  than  that  which  it  formerly  held,  requiring 
as  it  does  heavy  capital  for  its  successful  prosecution  as  a  business  in 
the  purchasing  of  improved  machinery  and  the  employment  of  skilled 
labor. 
HEEREN'S  MILK-TESTER. 
By  Joseph  W.  England. 
(Read  at  the  Pharmaceutical  Meeting,  January  19th.) 
Asa  possible  successor  to  the  lactometer  for  the  valuation  of  milk 
densities,  I  would  show  for  your  inspection  one  of  "Heeren's  Milk- 
Testers/'  manufactured  by  the  Hanover  Vulcanite  Co.,  of  Hanover, 
Germany.  There  is  only  one  agency  of  the  manufacturers,  I  believe, 
in  this  country,  and  that  is  located  at  Baltimore. 
.  The  directions  for  use  accompanying  the  " tester "  are  as  follows: 
"  Place  some  drops  of  the  milk  (not  boiled)  to  be  tested  on  the  middle 
of  the  black  plate,  and  then  lay  the  glass  plate,  with  its  colored 
side  turned  downward  on  the  milk,  so  that  the  transparent  part  of 
the  glass  plate  rests  on  it.  The  milk  thus  pressed  together  will 
assume  a  different  shade  of  color,  which  will  correspond,  or  nearly 
so,  with  one  of  the  various  shades  on  the  glass  plate,  and  the  quality 
of  the  milk  will  be  indicated  by  the  scale  on  the  edge  of  the  plate." 
Now,  the  principle  upon  which  this  " tester"  seems  to  rest  is 
apparently  dependent  upon  the  action  of  the  light  rays  in  traversing 
through  the  flattened  sample  of  the  milk  upon  the  central  disk  of 
vulcanite,  which  encounter  a  resistance  in  their  passage  through  the 
film  of  liquid  proportionate  to  its  opacity,  so  that  when  a  relatively 
thick  liquid  like  " cream"  is  taken  for  inspection,  the  light  rays  are 
almost  wholly  intercepted  in  their  passage,  and  the  color  afforded  by 
the  test  is  almost  white. 
Then,  reversely,  "very  poor  milk"  affords  almost  black  color,  or 
rather,  a  deep  bluish-black,  from  the  relative  ease  with  which  the 
light  rays  penetrate  to  the  black  disk;  the  intermediate  grades,  which 
vary  between  " cream"  as  the  highest,  and  "very  poor  milk"  as  the 
lowest,  being  known  as  "very  fat  milk,"  "normal,"  "less  fat,"  and 
