irm.j    Dose  Measures  and  Measured  Doses.  133 
Table  No.  7.— SHOWING  NUMBER  OF  DROPS  REQUIRED  TO  WEIGH  1  GRAMME. 
Diameter. 
Normal. 
DIST'D  WATER. 
dil'd  alcohol. 
ALCOHOL. 
High. 
I<ow. 
High. 
L,ow. 
High. 
L,ow. 
26 
13 
50 
20 
68 
45 
r\  t*r\n  n  c\ 
3  m.m. 
25 
18 
54 
•  42 
73 
52 
3  m.m. 
20 
20 
10 
44 
26 
54 
33 
Bent  
2m. m. 
28 
32 
10 
70 
30 
90 
35 
3m. m. 
20 
22 
10 
48 
26 
65 
36 
French  
7mm. 
10 
14 
10 
40 
24 
47 
29 
Large  bulb  
i8m.m. 
8 
9 
8 
22 
20 
28 
26 
9  m.m. 
10 
10-5 
9"5 
28 
36 
33 
Dropping  bottle  .... 
10 
12 
10 
33 
29 
36 
32 
One  thought  that  was  suggested  by  the  results  obtained  was,  that 
a  drop  of  water,  weighing  the  one- tenth  part  of  a  gramme,  was  a 
relatively  more  constant  quantity,  and  one  that  could  be  more  easily 
duplicated,  than  the  proposed  standard  drop  weighing  the  one- 
twentieth  part  of  a  gramme.  This  proposed  standard  drop  is  rather 
difficult  to  obtain  without  considerable  variation  or  error.  One 
improvement  in  the  pipette,  as  proposed  by  Dr.  Seaman  to  the 
Pharmacopoeia!  Revision  Committee,  suggested  itself.  This  is,  to 
grind  the  lower  edge  or  mouth  of  the  pipette;  this  appears  to  retard 
the  crawling  up  of  the  liquid  and  the  consequent  increase  in  the 
dropping  surface.  But  even  with  this  modification,  we  still  have  a 
possible  variation  of  more  than  30  per  cent. 
If  we  modify  the  "French  pipette"  in  the  same  way,  we  can 
reduce  the  variation  to  less  than  20  per  cent. ;  and  in  addition  to  this 
we  would  practically  establish  the  proposition  that  a  drop  of  distilled 
water  is  a  metric  quantity,  being  equal  in  weight  to  one  decigramme, 
or  in  bulk  to  the  one-tenth  part  of  a  cubic  centimetre. 
It  is  possible,  however,  to  bring  the  drop  of  distilled  water  still 
nearer  to  a  fixed  metric  standard.  If  we  had  a  perfectly  round 
sphere,  of  from  7  to  9  m.m.  in  diameter,  arranged  so  as  to  allow 
drops  of  water  to  form  and  drop  from  it,  we  would  find  that  these 
drops  were  so  regular  in  size  and  weight  that  they  might  be  used 
as  a  standard  of  weight  and  bulk.  To  all  intents  and  purposes  this 
would  at  least  equal  in  accuracy  the  plump  grain  of  wheat  that  is 
the  standard  of  weight  for  the  various  systems  at  the  present  time. 
