ADVANTAGES  OF  THE  TWADDLE'S  AREOMETER  343 
viscid  oleaginous  matter,  and  the  evolution  of  a  remarkable 
aromatic  and  semi-resinous  odor,  approximating  to  that  produced 
from  the  common  pastiles,  for  which  they  would  form  not  an  in- 
appropriate substitute,  either  in  the  sick  chamber,  or  on  such  oc- 
casions where  an  agreeable  impregnation  of  the  atmosphere  was 
required. — Pharmaceutical  Journal,  March,  1855. 
ON  THE  ADVANTAGES  OF  THE  TWADDLE'S  AREOMETER  OVER 
THOSE  OF  BEAUME  AND  BECK. 
By  Dr.  Bolley. 
It  appears  very  desirable  to  call  the  attention  of  chemists  to 
Twaddle's  areometer,  not  merely  because  the  specific  gravities  of 
fluids' heavier  than  water  are  always  expressed  in  accordance  with 
this  instrument  in  the  copious  technical  literature  of  England,  but 
also  because  this  areometer  has  great  advantages  over  those  in 
use  on  the  continent,  and  deserves  to  take  their  place.  In  all 
the  ehemical  factories  of  England  which  the  writer  had  an 
opportunity  of  visiting,  he  became  convinced  that  Twaddle's 
areometer  fully  deserved  the  estimation  in  which  it  is  held  by 
German  and  French  manufacturing  chemists  who  visit  England, 
even  though  previously  accustomed  to  Beaume's 
The  advantages  of  this  instrument  are, — 1st,  that  for  the  dis- 
tinction of  the  specific  gravities  between  1-000  and  2-000,  it  con- 
tains 200  degrees,  so  that  it  indicates  much  smaller  differences  in 
the  density  of  fluids  than  Beaume's  areometer,  which  has  only 
76  degrees  between  1«000  and  2-000  spec.  grav.  One  bad  result 
of  such  a  more  exact  division  would  be  the  necesssity  of  employ- 
ing a  very  long  scale,  or  having  very  small  degrees ;  but  both 
these  disadvantages  are  to  a  certain  extent  avoided  by  making 
the  entire  apparatus  consist  of  six  areometers,  of  which  the  first 
ranges  from  0°  to  26°,  the  second  from  24Q  to  60°,  and  so  forth. 
The  whole  scale  of  degrees  thus  reaches  a  length  of  about  26 
inches. 
*2.  Each  degree  represents  a  constant  progression  of  the  specific 
gravity,  so  that,  supposing  we  know  the  very  simple  principle  of 
the  division,  on  reading  off  the  degree  We  immediately  obtain  the 
corresponding  density  of  the  fluids.  The  principle  of  this  division 
is  as  follows: — The  specific  gravity  of  water  being  set  at  1-000, 
