802  Scientific  and  Technical  Abstracts.     { AaL^;^rm- 
I —  Carbon  monoxide  is  the  only  considerable  toxic  substance 
in  the  exhaust  gas  from  gasoline.  From  benzol  and  illuminating 
gas,  accessory  poisonous  substances  result  in  the  exhaust. 
II —  A  concentration  of  15  parts  of  carbon  monoxide  per  10,000 
parts  of  air  is  dangerous  to  life. 
III —  If  a  car  while  "warming  up"  should  give  off  1  cubic  foot 
of  carbon  monoxide  per  minute  in  a  closed  room  10  by  10  by  20  feet, 
the  atmosphere  would  reach  the  dangerous  concentration  of  15 
parts  per  10,000  in  three  minutes,  R.  P.  F. —  (Abstracted  from  Pub. 
Health  Reports,  United  States  Public  Health  Service,  Vol.  36,  Xo. 
36,  Sept.  9,  1 92 1.) 
Estimation  of  Salicylates  and  Phenol. — In  a  method  pro- 
posed for  the  estimation  of  these  compounds  advantage  is  taken  of 
the  characteristic  behavior  of  the  constituents  phenol  and  salicylic 
acid  towards  iodine ;  the  final  product  of  the  reaction  in  the  pres- 
ence of  alkali  or  alkaline  carbonate  is  a  purplish-red  amorphous 
compound  C6H2I20,  termed  diiodophenylene  oxide  or  tetraiodo- 
phenylene  quinone.    The  reaction  is  represented  by  the  equations : 
2C6H5OH+6I2+4Na2C03=2CGH2I20+8XaI+4C02+4H20. 
2C6H40HC02H+6I2+4Na2C03=2C6H2I20+8NaI+6C02+4H20. 
Each  molecule  of  phenol,  salicylic,  or  acetylsalicylic  acid  yields  one 
molecule  of  the  iodine  compound,  whilst  one  molecule  of  salol  yields 
two  molecules  of  the  same  compound.  In  the  case  of  salol,  about 
0.1  gm.  of  the  sample  is  weighed  on  to  a  small  dry  filter  and  washed 
with  successive  quantities  of  chloroform  until  all  soluble  substances 
have  been  dissolved;  the  chloroform  solution  is  evaporated  at  the 
ordinary  temperature  in  a  conical  flask,  the  dry  residue  obtained 
is  treated  with  10  cc.  of  a  1  per  cent,  sodium  hydroxide  solution, 
and  the  mixture  heated  under  a  reflux  apparatus  so  that  boiling 
begins  in  about  two  minutes.  Successive  quantities  of  10,  30,  and 
50  cc.  of  water  are  then  added,  the  heating  being  so  regulated  that 
the  mixture  begins  to  boil  in  about  3,  5,  and  10  minute  intervals 
respectively.  Just  before  the  last  addition  of  water,  1  gm.  of  dry 
sodium  carbonate  is  introduced  into  the  top  of  the  condenser  and 
washed  down  with  the  water.  To  the  clear  boiling  solution  is 
now  added  60  cc.  for  an  excess)  of  N/5  iodine  solution,  the  mix- 
ture again  boiled,  the  condenser  then  rinsed  with  a  small  quantity 
