Am'M°ay'i^2iarm' }  Analytical  Characteristics  of  Talcum.  319 
use.  The  powdered  talcum  offered  for  use  in  the  manufacture  of 
toilet  talcum  varies  considerably  in  "fluffiness."  A  recent  examina- 
tion of  five  lots  from  different  sources  showed  densities  of  104, 
9.09,  9.36,  9.0  and  9.72  respectively  when  tested  with  the  standard- 
ized cup  described  above. 
Sifting  Quality. — This  is  important  because  of  the  necessity  of 
seiving  powdered  talcum  owing  to  the  presence  of  particles  of 
extraneous  matters  and  unground  talcum  in  commercial  shipments. 
Sifting  is  also  necessary  in  order  to  disintegrate  lumps.  The 
sifting  quality  is  also  important  from  the  standpoint  of  ease  with 
which  it  can  be  shaken  from  the  market  container  of  toilet  talcum, 
in  which  it  is  finally  used.  Commercial  talcums  vary  greatly  in 
their  sifting  qualities,  some  lots  being  very  difficult  to  handle  be- 
cause of  their  tendency  to  clump  up  and  thus  refuse  to  pass  through 
the  seive.  Considerable  expense  and  trouble  can  be  eliminated  by 
careful  selection  of  powdered  talcum  in  this  respect.  The  fineness 
of  subdivision,  density,  adhering  ability  and  moisture  content  all 
influence  the  sifting  quality  of  a  powdered  talcum. 
Freedom  from  Dampness. — Freedom  from  dampness  is  neces- 
sary as  affecting  chiefly  the  sifting  qualities;  dampness  rendering 
sifting  very  slow  and  tedious.  Dampness  also  affects  the  color  and 
density,  both  of  these  characteristics  being  deleteriously  altered. 
No  exact  figure  for  maximum  moisture  content  can  be  laid  down 
as  satisfactory  for  all  lots  of  talcums,  but  in  most  cases  not  more 
than  3  per  cent,  of  moisture  should  be  lost  by  powdered  talcum  when 
dried  at  ioo°C.  to  constant  weight. 
Chemical  Characteristics. — Talcum  is  essentially  a  native 
hydrous  magnesium-aluminum  silicate,  but  may  be  associated  with 
numerous  other  substances.  The  chemical  characteristics  of  talcum 
and  associated  substances  materially  affect  the  physical  tests  dis- 
cussed above  but  any  baleful  influences  may  be  avoided  by  selecting 
material  in  strict  accordance  with  these  physical  tests. 
As  a  matter  of  fact,  it  is  only  by  the  application  of  the  careful 
analytical  tests  mentioned  in  this  communication  that  a  high-grade 
toilet  talcum  can  be  produced. 
Pharmaceutical  Research  Laboratories, 
H.  K.  Mulford  Company, 
Philadelphia,  Pa. 
