368 
Polarization  by  Mixtures. 
f  Am  Jour.  Pharm. 
1     August,  1901. 
A  more  satisfactory  method  consisted  in  taking  a  piece  of  hard 
glass  tubing,  2-51  cm.  outside,  and  2-15  cm.  inside  diameters,  and 
cutting  as  great  a  length  as  could  be  used  in  the  instrument,  and 
cementing  plates  of  glass  over  each  end.  Fig.  1  shows  the  arrange- 
ment indicated.  The  cement  used  was  melted  asphalt,  commonly 
known  as  "  sidewalk  pitch."  It  would  be  difficult  to  find  a  more 
perfect  cement  for  glass  than  this  substance  ;  it  is  water  proof, 
Fig.  ia. — Side  view. 
Fig.  ib. — General  view  of  tube. 
0 
Fig.  ic. — Direct  end  views  of  tube. 
and  many  of  the  common  chemicals  do  not  affect  it.  Another 
variety,  known  as  "  roofing  pitch  "  is  good,  but  more  viscous,  and 
not  so  well  adapted  for  permanent  strain. 
A  solution  of  glucose  was  placed  in  this  tube  and  the  end 
cemented  on,  leaving  a  small  space  as  shown  in  the  figure.  Through 
this  space  the  liquid  could  be  introduced  by  means  of  a  pipette, 
and  when  once  filled  the  surface  tension  was  sufficient  to  retain  it. 
