"^"October,  mi"'"" }       ^^^^  ^«  "^^^^y  of  Formaldehyde.  469 
an  idea  as  to  degree  of  variation  in  the  strength  of  the  commercial 
formaldehyde  on  the  American  market.  Accordingly,  samples  were 
obtained  from  the  principal  American  firms  who  sell  this  article. 
And  inasmuch  as,  for  the  reasons  given  above,  the  KCN  method 
may  be  considered  as  more  reliable  for  determining  the  actual 
formaldehyde  content  of  such  solutions,  the  determinations  were 
carried  out  by  this  method.  Seven  samples  were  examined.  The 
results  obtained  are  given  in  Table  IV. 
Table  IV. 
Showing  the  HCHO  Strength  of  Various  Samples  of  Commercial 
Formaldehyde. 
)t  sample 
Amount  of 
formaldehyde  'l 
solution  taken 
ant  of  N/10 
N  added  e 
ant  of  N/io 
NO3  used 
10  KCNS 
red  for  -J  of 
filtrate 
equivalent  of 
)rmaldehyde 
)n  in  terms  of 
10  AgNOa 
nt  of  HCHO 
ssed  in  per- 
ge  by  weight 
d 
0  U 
aw 
S  0.  G 
< 
< 
6  X  flj 
(c.  c.) 
(c.  c.) 
(c.  c.) 
(c.  c.) 
(c.  c.) 
(Per  cent.) 
I 
25 
48 
20 
1-75 
31.10 
35-47 
2 
25 
48 
20 
2.05 
31-74 
36.11 
3 
25 
48 
20 
2.00 
31.64 
36.21 
4 
25 
48 
20 
2.30 
32.25 
36.53 
5 
25 
48 
20 
2-35 
32.34 
36.61 
6 
25 
48 
20 
2.40 
32.44 
36.98 
7 
25 
48 
20 
2.91 
33-46 
37-97 
d  These  solutions  of  formaldehyde  contained  the  following  amounts  in  grams  of  the 
respective  samples  of  the  concentrated  formaldehyde  in  2000  c.  c:  No.  i,  21.0418;  No.  2, 
31.0958;  No.  3,  20.9690;  No.  4,  21.1879;  No.  5,  21.2005;  No.  6,  21.0512;  No.  7,  21.1459. 
eThe  found  value  of  the  KCN  solution  was  as  follows:  In  the  case  of  No.  i,  48  c.  c.  was 
equivalent  to  47.6  c.  c,  N/io  AgNOs;  in  No.  4,  to  47.65;  and  in  the  remainder,  to  47.64  c.  c. 
N/io  AgNOs. 
The  results  given  in  Table  IV  show  that  the  majority  of  the 
samples  examined  contained  slightly  less  formaldehyde  than  is 
required  by  the  present  U.S. P.  (''not  less  than  37  per  cent,  by 
weight"),  and  that  only  two  (Nos.  6  and  7)  of  the  seven  samples 
examined  may  be  said  to  have  come  up  to  its  requirement.  Similar 
results  have  also  been  obtained  by  Evans  Sons  Lescher  and  Webb,-' 
who  found  that  the  nine  samples  of  commercial  formaldehyde  solu- 
tion which  they  examined  ranged  from  37  down  to  35.4  per  cent. 
^' Evans  Sons  Lescher  and  Webb:  Analytical  Notes,  1907,  1908,  p.  22. 
