Amju^'wS?rm"}   Some  Brands  of  Hydrogen  Peroxide.  277 
phthalein  as  indicator.  Ten  cubic  centimetres  of  the  sample  was 
tested  in  each  case,  the  figures  in  the  table  representing  the  average 
of  results. 
Fifty  cubic  centimetres  were  evaporated  at  a  low  heat  to  dryness 
and  both  residue  and  the  original  sample  tested  for  chloride,  sul- 
phate, phosphate,  fluoride,  borate,  barium  and  other  metals  by  the 
usual  processes  of  the  laboratory.  Sodium  and  potassium  were 
recognized  by  the  Bunsen  flame. 
Each  sample  underwent  the  same  treatment,  and  attention  may 
be  called  to  the  fact  that,  however  widely  these  results  differ  from 
results  of  other  investigators,  they  are,  as  they  claim  to  be,  compari- 
sons. The  same  weights,  measures  and  solutions  were  used  in 
every  instance,  in  order  to  guarantee  uniformity. 
Generally  more  than  one  bottle  of  a  brand  was  examined  and  the 
volume  of  oxygen  was  found  to  vary  considerably,  no  doubt  depen- 
dent largely  on  age.  Of  the  Peuchot  brand,  it  is  claimed,  however,  it 
"  can  be  left  open  and  exposed  to  the  air  without  losing  strength." 
Specific  Gravity. 
Volume  of  Oxygen. 
Volume  of  Oxygen 
after  having  been 
opened  at  least  24 
hours. 
Acidity.  Milligrams 
of  KOH  for  10  cc. 
Residue  in  50  cc. 
Milligrams. 
Sulphuric  acid  or 
Sulphate. 
Metals. 
Other  matter. 
0.  a, ....  . 
rono. 
.013-5— 12-0 
013-0 
6'45 
30-0 
trace 
Sodium 
present 
Marchand,  .  . 
ron6 
13-5— aio'4 
10-3-0  IO'O 
25-16 
50-6 
present 
Sodium 
boric  acid 
I '01 10 
10-5 — 09-8 
«9'45 
6-83 
60 -o 
present 
Sodium 
Potassium 
none 
Peuchot  No.  2, 
1*0120 
1176 
7-20 
150-0 
trace 
Calcium 
Sodium 
Potassium 
(trace) 
glycerine 
Peuchot  No.  1, 
1-0136 
i2'5 — <z6-i 
04-05 
9-85 
320-0 
present 
Sodium 
present 
All  the  samples  contained  HC1  or  chloride,  and  phosphoric  acid 
or  phosphate  (Bene  merely  a  trace) ;  but  were  free  from  barium, 
except  P.  No.  I,  which  contained  a  trace. 
In  the  residue  from  Marchand's  solution  no  chloride  could  be 
found ;  the  solution,  however,  evidently  contained  hydrochloric 
acid,  which  must  have  been  driven  off  during  evaporation,  the 
excess  of  sulphuric  acid  preventing  the  formation  of  chlorides. 
