486       Recent  Literature  Relating  to  Pharmacy.  \^o^l^lmm' 
of  the  samples  examined  led  him  to  the  conclusion  that  the  main 
ingredient  is  an  ester,  which  is  saponified  by  the  alcoholic  potassa 
used  in  the  above  process.  He  also  finds  that  no  definite  iodine 
absorption  number  can  be  obtained,  but  he  thinks  that  the  index  of 
refraction  of  a  20  per  cent,  solution  in  linseed  oil  may  prove  of 
analytical  value.  H.  V.  A. 
A  NEW  METHOD  FOR  ESTIMATING  FORMALDEHYDE. 
0.  Blank  and  H.  Finkenbeiner,  Ber.  d.  Deut.  chem.  Ges.,  1898^7, 
2979,  state  that  the  ammonia  process  for  estimating  formaldehyde 
gives  lower  results  than  several  of  the  other  technical  methods  that 
agree  well  among  themselves.  They  offer  a  new  method,  which  gives 
very  good  results.  It  consists  in  oxidizing  the  formaldehyde,  in  a 
definite  amount  of  standardized  alkaline  solution,  to  formic  acid,  by 
means  of  hydrogen  peroxide,  and  then  estimating  the  amount  of 
caustic  not  neutralized.  The  method  is  as  follows  :  place  3  grammes 
of  solution  or  I  gramme  of  solid  formaldehyde  into  a  tall  Erlen- 
meyer  flask,  containing  from  2  5  to  30  c  c.  of  double  normal  caustic  soda 
solution;  then  add  gradually,  during  three  minutes,  50  c.c.  of  2  5  to 
3  per  cent,  of  pure  hydrogen  peroxide,  through  a  funnel  placed  in 
the  neck  of  the  flask.  Allow  to  stand  two  or  three  minutes,  then 
estimate  the  amount  of  unused  alkali,  with  double  normal  sul- 
phuric acid,  using  litmus  as  indicator.  Solutions  containing  less 
than  30  per  cent,  of  formaldehyde  must  be  allowed  to  stand  not 
less  than  ten  minutes,  after  the  hydrogen  peroxide  has  been  added, 
so  that  complete  oxidation  will  result.  The  per  cent,  of  formalde- 
hyde is  found  by  multiplying  the  number  of  cubic  centimeters  of 
alkaline  solution  used,  by  two,  if  3  grammes  of  substance  are  taken, 
and  by  six  when  I  gramme  is  employed. 
The  presence  of  acetaldehyde,  paraldehyde  or  benzaldehyde  is 
liable  to  vitiate  the  results.  L.  F.  K. 
STABILITY  OF  OXALIC  ACID  SOLUTIONS. 
W.  P.  Jorissen,  Maandbl.  naturzv.,  22,  100;  from  Chem.  Centrbl. 
(1898),  1084.  Oxalic  acid  solutions,  in  the  presence  of  light,  are  de- 
composed by  oxygen,  but  in  the  dark  the  solutions  are  stable, 
except  that  they  may  be  decomposed  by  fungi.  Two  to  three  per  cent, 
solutions  are  poisonous  to  mould  fungi.  Alcoholic  oxalic  acid  solu- 
tions diminish  in  strength  even  in  the  dark ;  this  is  probably  due  to 
the  formation  of  esters.  L.  F.  K. 
