506  Mr.  de  luc  on 
ready  fo  near  to  the  progreffion  of  the  quickfilver  Tber- 
mometer  itfelf,  that  the  effect  of  the  differences  of  the 
fpirituofity  almoft  entirely  vanifhes ; fo  that  there  would 
be  little  error  in  taking  as  proportional  to  the  total  aug- 
mentation of  bulk  at  20°  of  a certain  liquor  diftilled 
from  wine,  the  intermediate  dilatations  of  every  other 
liquor  of  the  fame  kind. 
It  is  poffible,  however,  ftill  to  leffen  thefe  errors,  with- 
out having  more  than  two  terms  of  comparifon  by  ex- 
pedience, by  taking  thefe  terms  within  the  limits  of  the 
probable  obfervations,  and  that  for  two  reafons.  The 
firft,  that  the  more  numerous  obfervations  will  probably 
be  made  nearer  the  points  where  true  proportions  have 
been  found  by  experience.  The  other,  that  the  greateft 
deviation  will  be  ftill  more  leffened,  by  throwing  part  of 
the  errors  beyond  the  two  real  points  of  comparifon,  in 
order 
li  pres  de  la  marcfoe  du  Therinometre  meme,  que  1’effet  des  differences  de  fpi« 
ri^uoiite  s’evanouit  prefque  entierement;  et  qu’il  y auroit  pen  d’erreur  a regarder 
comme  proportionnelle  affaugmentation  totale  de  volume  a 20°  d’une  certain© 
liqueur  diftillee  du  vin,  les  augmentations  intermediares  de  toute  autre  liqueur 
du  meme  genre. 
On  peut  cependant  diminuer  encore  ces  erreurs,  fans  avoir  plus  de  deux  termed 
de  comparaifon  par  l’experience,  en  prenant  ces  termes  en  dedans  meme  des  limiteg 
des  obfervations  probables;  et  cela  par  deux  confiderations.  La  premiere  que  les 
obfervations  les  plus  nombreufes  fe  trouveront  probablement  plus  pres  des  vrais 
rapports  fixes  par  Texperience;  Tautre  que  le  plus  grand  ©cart  diminy era  encore* 
