DENTIFRICES. 
537 
Valerianate  of  Zinc. 
The  question  proposed  for  solution  in  the  list  of  subjects  now 
under  the  notice  of  the  Conference  in  connection  with  this  sub- 
stance is  :  Describe  an  easy  method  of  determining  the  purity  of 
valerianate  of  zinc  as  found  in  commerce  ?  In  answer  to  this, 
I  wish  to  say  that  I  have  not  had  time  to  carry  out  any  great 
number  of  experiments  on  the  subject,  but  I  find  that  pure  vale- 
rianate of  zinc  dissolves  readily  in  a  dilute  solution  of  citric  or 
tartaric  acid,  without  separation  of  the  valerianic  acid,  as  is  the 
case  when  sulphuric  or  hydrochloric  acid  are  used.  Oxide  *of  zinc 
is  insoluble  in  dilute  vegetable  acids,  so  that  supposing  a  sample 
were  tested  which  had  been  made  by  rubbing  up  valerianic  acid 
with  oxide  of  zinc,  the  specimen  would  remain  insoluble.  If 
acetate  of  zinc  had  been  used  as  a  substitute,  this  would  dissolve, 
but  it  would  also  dissolve  in  water.  Therefore,  if  a  specimen  is 
tested  and  found  to  be  insoluble  in  water  but  dissolves  pretty 
readily  in  a  cold  weak  solution  of  citric  or  tartaric  acid,  we  may 
infer  that  the  preparation  is  pure. — London  Pliarm.  Jour.,  Sept., 
1866. 
DENTIFRICES. 
By  Dr.  C.  E.  Francis. 
Read  before  the  Brooklyn  Dental  Association,  April  4th,  1866. 
From  dens,  a  tooth,  and  fricaro,  to  rub. 
This  term  is  applied  to  preparations  used  for  cleaning  the 
teeth  and  tending  to  their  preservation.  Numberless  prepara- 
tions under  the  name  of  dentrifices  have  been  spread  before  the 
public,  and  numerous  have  been  the  substances  employed  in  their 
manufacture. 
Nearly  every  pharmaceutist  in  the  land  has  from  one  to  a 
dozen  preparations  for  the  teeth  to  offer  his  customers,  and  every 
vender  of  cosmetics  has  some  favorite  nostrum  to  recommend. 
They  are  in  the  form  of  powders,  pastes,  soaps  and  lotions. 
Many  of  these  preparations  are  undoubtedly  of  benefit  to  those 
who  are  in  the  habit  of  using  them,  and  many  of  them  perhaps 
do  more  mischief  than  good.  How  long  a  period  dentifrices  have 
been  in  use,  I  am  not  able  to  say,  but  we  find  formulas  for  tooth- 
