146 
Sjyecific  Gravity  and  Increase  in  Volume.  {^"^^Aimi'im^ 
The  results  given  in  the  table  are  all  calculated  for  one  hundred 
'2:rams  of  substance. 
It  was  thought  desiral)le,  while  mj\king  these  experiments,  to  also 
ascertain  the  specific  gravity  of  the  substance  in  the  solid  state  and  in 
solution.  To  ascertain  the  specific  gravity  of  the  substance  in  solution, 
it  was  only  necessary  to  note  the  increase  in  volume  or  the  amount  of 
water  displaced,  and  dividing  the  weight  of  the  substance  used  by  the 
increase  in  volume  of  the  liquid.  It  was  found  more  difficult  to  ascer- 
tain the  correct  specific  gra^'ity  of  some  of  the  solids,  owing  to  the 
difiiculty  of  obtaining  them  in  perfect  crystals.  In  a  number  of  in- 
stances, however,  the  decimals  agreed  in  both  experiments.  With 
potassium  nitrate  and  potassium  bromide  it  was  found  especially  diffi- 
cult to  make  any  two  experiments  agree ;  in  the  former,  owing  to  the 
cavities  contained  in  the  crystals  filled  with  the  mother  liquor,  nume- 
rous experiments  were  made  with  different  crystals,  some  being  so 
small,  thin  and  transparent,  that  it  was  thought  they  could  not  possibly 
contain  any  mother  liquor,  l)ut  these  gaxe  no  better  results  than  others. 
A  few  crystals  were  then  selected,  placed  in  strong  alcohol  and  allowed 
to  remain  several  days,  then  carefully  removed,  dried  and  the  specific 
gravity  again  taken.  On  comparison,  no  two  of  these  results  agreed 
either  with  themselves  or  with  the  specific  gravity  of  each  crystal  taken 
before  being  placed  in  alcohol. 
In  the  summary  of  the  results  of  different  specific  gravities  obtained 
in  the  air,  it  was  thought  advisable  to  make  comparison  of  these  with 
the  results  of  others,  as  given  in  Watt's  Dictionary  of  Chemistry," 
Gnielin's  Handbuch,"  and  other  standard  works. 
The  specific  gravity  of  su])stances  were  taken  at  least  twice.  In 
every  instance  where  the  specific  gravity  of  a  substance  is  given  in 
^solution  the  specific  gravity  of  the  solid  substance  used  has  also  been 
determined. 
u  O 
Substance. 
Acidum  citricum, 
Acidum  oxalicum,  C.  P., 
Specific  Gravity  of  Solid. 
1-557 
1-57 
(Bodeker,  1-63) 
<S-(  (— I 
I  1 
<  s 
cc. 
200 
300 
400 
1000 
1500 
2000 
=  .2  S 
CC. 
263 
361 
459 
1070 
1565 
2060 
">  a 
u  a 
a)  o 
o  a 
«  as 
a>  ^ 
P-  3 
CO  (72 
1-587 
1-639 
1-695 
1-429 
1-538 
1-667 
