500  Mr.  de  luc  on 
fliould  afterwards  mark  the  temperature  of  this  liquor, 
one  was  to  take  terms  very  diftant  from  each  other,  as  for 
inftance  the  freezing  and  boiling  points;  whilft  on  the 
other  hand,  by  keeping  within  the  temperatures  in 
which  the  trials  fliould  be  made,  one  would  come  fo  near 
the  truth,  that  the  differences  would  be  imperceptible. 
This  inftance,  in  itfelf  ufeful,  being  proper  to  be  ap- 
plied to  every  cafe  in  which  we  wifli  to  compare  with 
one  another  phyflcal  effedfs  which  depend  upon  the 
fame  caufe,  that  we  may  afterwards  judge  of  them  all 
by  one,  I ihall  dwell  upon  it  a little  while  to  give  a full 
explanation  of  it. 
I fuppofe  that  the  experiments  intended  to  effay 
the  fpirituofity  of  different  liquors  diftilled  from 
wine,  by  the  fpecific  gravities  of  them,  are  made  be- 
tween the  temperatures  which  anfwer  to  32°  and  77® 
of 
perature  de  cette  liqueur,  on  prenoit  destermes  fort  eloignes,  comme  la  congela- 
tion et  1’eau  bouillante:  tandis  qu’au  contraire,  en  fe  renfermant  dans  les  tem- 
peratures ou  les  epreuves  feroient  fakes,  on  approcheroit  li  fort  de  la  verite,  que 
les  differences  feroient  imperceptibles. 
Cet  exemple  ayant  quelque  utilite  par  lui-meme,  et  pouvant  etre  applique  a 
toute  forte  de  cas  ou  l’on  compare  entr’eux  des  effets  phyliques  dependants  d’une 
meme  caufe,  pour  juger  enfuite  de  tous  par  un  feul,  je  m’y  arreterai  afin  de  le 
inieux  eclaircir. 
Je  fuppoferai  que  les  experiences  deftinees  aeprouver  les  degres  de  fpirituohte 
des  diverfes  liqueurs  diftillees  du  vin,  parleur  pefanteur  fpecifique,  fe  ferontentre 
les  temperatures  qui  correfpondent  a 320  et  770  fur  le  Thermometre  de  Fah- 
renheit 
7 
