ON  CHLOROFORM. 
297 
gr.  1*490.  My  plan  for  these  cocks  was  much  simplified  by  Mr. 
T.  M.  Hammett  of  this  city,  who  constructed  them  so  that  they 
worked  admirably  during  the  long  time  they  were  continually  in 
use ;  they  measured  the  weight  for  which  they  were  graduated, 
invariably  correct,  and  a  great  deal  of  time,  labor  and  loss  of 
material  was  saved  thereby.  One  was  first  made  for  measuring 
half  a  pound  of  ether,  sp.  gr.  725,  and  finding  it  so  admirably 
adapted  to  meet  all  requirements,  they  were  likewise  adopted 
for  the  chloroform,  and  I  believe  would  answer  equally  well  for 
all  costly  and  volatile  liquids. 
The  plug  of  these  measuring  cocks  is  of  an  obconical  shape 
and  hollow,  and  is  perforated  at  two  places,  namely,  just  at  its 
base  even  with  the  bottom,  and  perpendicularly  above  this  point 
even  w7ith  the  top.  When  these  perforations  are  turned  towards 
the  tank,  the  lowest  one  connects  directly  with  the  inside  and 
admits  the  liquid,  while  the  upper  one  communicates  by  means 
of  a  tube  with  the  top  of  the  tank,  to  remove  the  air  from  the 
cock  into  the  tank ;  the  measure  is  filled  as  soon  as  the  liquid 
appears  in  the  glass  tube  which  forms  the  lower  portion  of 
the  connecting  tube  just  mentioned.  A  half  turn  is  now  given 
to  the  plug  when  the  liquid  is  discharged  from  the  lower 
opening  through  the  nozzle,  while  the  hollow  space  is  again 
filled  with  air  through  a  groove  in  the  top  of  the  cock,  just  com- 
municating with  the  upper  opening,  without  the  possibility  of 
loss  by  evaporation.  By  turning  alternately  to  the  right  and  to 
the  left,  the  measuring  cock  is  filled  and  emptied  in  reciprocal 
succession. 
In  the  beginning  of  the  manufacture  of  chloroform  at  the  U. 
S.  Laboratory,  deodorized  alcohol,  the  so-called  cologne  spirit, 
was  employed.  This  alcohol  is  purified  from  the  greatest  but 
not  the  entire  amount  of  fusel  oil ;  subsequently  ordinary  com- 
mercial alcohol,  containing  a  larger  proportion  of  fusel  oil,  was 
used,  and  the  chloroform  obtained  was  quite  as  good  as  from  the 
former  source,  if  the  requisite  care  was  taken  during  the  process 
of  purification  and  rectification.  At  various  times  experiments 
were  made  with  precisely  the  same  good  success,  with  alcohol 
obtained  by  the  distillation  of  the  dregs  from  the  manufacture 
of  certain  fluid  extracts.    This  alcohol  was  usually  regenerated 
