484  Analysis  of  Coal  Tar  Preparations.  {Am-/eXi32?rm" 
tered,  and  the  solution  precipitated  with  alcohol.  The  amyloid 
separates  as  a  jelly,  and  is  purified  by  redissolving  in  water  and 
again  precipitating  with  alcohol.  It  then  forms  a  colorless,  trans- 
parent jelly,  which  dries  in  the  desiccator  to  an  amorphous,  vesicu- 
lar mass,  and  is  colored  blue  by  iodine,  the  color  disappearing  on 
warming.  Its  aqueous  solutionis  dextrorotatory  ([«]D  =  93-5°), and 
it  is  not  converted  into  sugars  by  diastase  ;  on  oxidation  with  nitric 
acid,  it  yields  mucic  acid,  and  with  hydrochloric  acid  gives  15-44 
per  cent,  of  furfuraldehyde.  On  hydrolysis  with  2-5  per  cent,  sul- 
phuric acid,  it  yields  galactose,  together  with  a  smaller  quantity  of 
another  hexose  of  lower  dextrorotatory  power,  and  a  pentose  which 
yields  trihydroxyglutaric  acid  on  oxidation,  and  is  therefore  proba- 
bly xylose,  the  second  hexose  being  probably  glucose.  If  the  resi- 
due, after  extracting  the  seeds  with  hot  water,  be  boiled  with  3  per 
cent,  sulphuric  acid,  it  yields  further  quantities  of  galactose  and 
xylose. 
The  author,  therefore,  regards  amyloid  as  a  substance  correspond 
ing  somewhat  with  starch  or  cellulose,  but  derived  from  galactose 
and  xylose,  instead  of  from  glucose.  Whether  the  substance  is 
•  really  homogeneous  is  not  yet  certain,  but  the  fact  that  the  amyloid 
prepared  from  the  seeds  of  Poeonia  officinalis  yields  almost  the  same 
quantities  of  mucic  acid  and  furfuraldehyde  is  in  favor  of  this  sup- 
position. 
THE  ANALYSIS  OF  COAL  TAR  PREPARATIONS.1 
By  H.  Helbing  and  Dr.  F.  W.  Passmore. 
The  value  of  preparations  of  tar  oils  as  disinfectants  is  becoming 
daily  more  and  more  appreciated  by  the  Medical  profession  and 
Sanitary  experts.  Yet  whilst  no  doubt  remains  that  the  tar  com- 
pounds are  disinfectants  par  excellence,  very  little  is  known  with 
respect  to  the  determination  of  the  individual  value  of  these  tar 
preparations  by  a  scientifically  accurate  and  yet  easy  method. 
That  the  disinfectant  value  of  such  compounds  may  be  established 
by  bacteriological  investigation  is  an  idea  that  at  once  presents 
itself  to  the  mind,  and  the  method  is  certainly  of  very  great  value  in 
experimenting  with  a  new  disinfectant  of  definite  composition. 
Bacteriological  research  is,  however,  not  of  so  much  use  in  the  com- 
1  Reprinted  from  Helbing' s  Pharmacological  Record,  July,  1892. 
