Am.  Jour.  Pharm.  \ 
April,  1888.  / 
Specific  Gravity. 
175 
drachm,  respectively,  being  equivalent,  of  course,  to  or  J  grain  of 
the  salt. 
Note. — Liquor  Hydrargyri  perchloridi,  Brit  Phar.,  consists  of 
corrosive  sublimate  10  grains,  ammonium  chloride  10  grains,  and  dis- 
tilled water  20  fluid  ounces  (imperial  measure.)  The  solution  of  the 
corrosive  sublimate  of  the  French,  Belgian  and  Portuguese  Pharma- 
<x)poeias  is  Van  Swieten^s  liquor  and  consists  of  one  part  of  corrosive 
sublimate  dissolved  in  900  parts  of  distilled  water  and  100  parts  of 
alcohol. — Editor. 
SPECIFIC  GRAVITY. 
By  a.  B.  Taylor,  Ph.  M. 
In  the  February  number  of  this  journal  I  suggested  an  easy  method 
of  taking  specific  gravities  of  liquids. 
Mr.  Eobert  B.  Warder  in  a  communication  to  the  Pharmaceutical 
Record,  March  1st,  in  commenting  upon  it  states  that  "the  essential 
point  of  the  suggestion  depends  merely  upon  giving  the  bulb  a  cer- 
tain volume,  so  that  it  will  displace  100  grains  of  water,  or  be  equal 
in  bulk  to  105  minims." 
While  this  is  true,  the  result  cannot  be  accomplished  in  any  other 
method  so  readily  as  by  making  the  weight  of  the  bulb  equal  in  num- 
ber of  grains  to  its  specific  gravity. 
For  example,  it  would  be  very  much  more  difficult  to  make  a  piece 
of  glass  of  such  a  size  that  it  should  displace  exactly  105  and  a  frac- 
tion minims  of  water,  or  a  certain  fractional  number  of  c.  c,  than  it 
would  be  to  make  it  weigh  the  number  of  grains  or  grammes  corres- 
ponding to  its  specific  gravity. 
Whether  measured  or  weighed,  its  size  would  be  exactly  the  same, 
and  no  matter  what  the  specific  gravity  of  the  bulb  may  be,  if  it 
measures  105  minims,  its  weight  will  be  exactly  one  hundred  times  the 
number  of  grains  corresponding  to  its  specific  gravity.  Here  is  an 
example  where  weighing  would  give  more  accurate  results  than 
measuring,  besides  being  much  more  practicable. 
The  remaining  parts  of  Mr.  Warder's  suggestion  "when  the  metric 
system  is  used,  it  might  occupy  10  c.c.  and  displace  10  grammes  of 
water,"  or,  "  glass  could  be  weighted  in  the  usual  way  to  exactly  200 
grains  or  20  grammes, "  differ  entirely  from  my  suggestion,  and  are 
simply  a  return  to  Gannal's  method,  for  description  of  which  see 
Remington's  Practice  of  Pharmacy,  p.  75. 
