ON  DROPS. 
525 
ments  "which  had  for  their  object  the  determination  of  how  far 
the  rapidity  of  dropping  influenced  the  size  of  the  drops,  and 
to  establish  the  fact  of  the  uniformity  between  the  size  of  drops 
falling  at  equal  intervals  of  time.  The  temperature  being  at 
28°-5  C,  the  flow  of  liquid  was  so  regulated  that  a  second 
elapsed  between  the  fall  of  each  drop.  Eight  batches  of  sixty 
drops  each  were  then  weighed  accurately,  and  were  found  to 
have  a  mean  weight  of  3-9767  grammes,  the  variation  between 
the  extremes  being  insignificant.  Thirty  batches  of  sixty  drops 
each  were  then  prepared,  the  growth-time  being  varied  six 
times  in  the  course  of  the  experiments,  and  ranging  between 
0435  to  0-767  of  a  second.  In  this  series  of  experiments  some 
curious  irregularities  occur  which  have  been  confirmed  by  other 
experiments.    The  following  table  will  show  this  : — 
Growth-time. 
Mean  Drop- 
Weight. 
Growth-time. 
Mean  Drop- 
Weight. 
Seconds. 
0-433 
0-500 
0-567 
Grammes. 
0-07540 
0  07275 
0-07456 
Seconds. 
0-635 
0-700 
0-767 
Grammes. 
0-07281 
0-07059 
006912 
It  will  be  seen  that  the  weight  of  a  drop  formed  in  0-500  of 
a  second  is  less  than  those  falling  either  in  0*567  of  a  second, 
or  0-633  of  a  second,  although  the  law  appears  to  be  at  first 
sight  that  the  weight  of  a  drop  should  diminish  as  its  growth- 
time  increases.  In  order  to  endeavor  to  establish  some  law 
with  respect  to  these  discrepancies,  Professor  Guthrie  undertook 
a  long  series  of  experiments :  the  growth-time  of  the  drops 
varying  from  the  third  of  a  second  to  twelve  seconds,  with  the 
following  result : — 
From  0"*333  growth-time  to  0"*433  there  is  diminution. 
"    0"*433       "       "       0"-450       "  increase. 
"    0"450       "       "       0"*467       "  diminution. 
"    0"-467      "       "       0"-500      "  increase. 
"    0"-500       "       «     12"-000       "     continual  dimin. 
On  the  whole,  the  law  seems  to  be  that  the  slower  the  drop- 
ping, the  smaller  the  drop.  It  was  found  too,  that  when  the 
time  between  the  drops  was  decreased  to  below  0-333,  a  contin- 
uous stream  was  the  result.  This  first  fact  is  most  interesting 
to  the  pharmacist,  as  showing  the  influence  of  rate  in  dispensing 
