THE  AMERICAN 
JOURNAL  OF  PHARMACY 
FEBRUARY,  1904. 
THERMOMETERS. 
By  Gustavus  Pii,k. 
The  thermometer  as  an  instrument  for  ascertaining  the  tempera- 
ture of  various  bodies  was  not  given  a  practical  form  till  less  than 
two  hundred  years  ago,  and  the  people  who  lived  before  that  time 
never  had  the  pleasure  of  knowing  how  hot  or  how  cold  they  were, 
and  no  one  ever  spoke  of  a  fall  in  mercury  or  a  rise  in  spirits.  It 
seems  strange  that  an  instrument  like  this  should  for  so  long  a  time 
have  escaped  the  attention  of  philosophers  and  thoughtful  minds, 
and  even  the  Chinese,  who  claim  to  be  the  originators  of  nearly 
everything  worth  inventing,  quite  overlooked  it,  and  it  remained  for 
an  Italian  doctor  to  first  conceive  of  a  method  to  indicate  the  tem- 
perature of  the  atmosphere.  It  was  about  the  beginning  of  the 
seventeenth  century  when  a  Doctor  Santorio,  of  Padua,  from  know- 
ing that  the  addition  of  heat  produced  an  expansion  of  air,  con- 
structed a  very  simple  affair  by  which  he  was  enabled  to  observe 
the  extent  of  expansion  that  took  place.  This  instrument  consisted 
of  a  long  tube  with  a  bulb  blown  on  one  extremity  and  left  open  at 
the  other  end.  The  open  end  was  placed  in  a  vessel  containing  a 
colored  liquid  and  the  ball  heated  with  a  lamp.  This  caused  the  air 
in  the  ball  to  expand  and  partly  escape  through  the  open  end. 
When  the  heat  was  withdrawn  and  the  air  in  the  ball  began  to  cool, 
a  contraction  took  place,  and  the  colored  liquid  rose  up  in  the  tube 
till  the  expansive  force  of  the  air  in  the  ball  was  the  same  as  the 
atmospheric  pressure  on  the  liquid.  There  was  no  scale  or  marking 
of  any  kind  attached  to  this,  only  the  rise  and  fail  of  the  column 
being  noted. 
(5i) 
