The "Rainbow"  Color  Trials  were   produced  to  experiment  with various different combinations   of  stamp and
cancellation inks.  The First Trial was  a small plate  of  three  impressions  without  corner letters and with the top
right corner of each impression voided.  The impressions of  this trial show the "O" Flaw   later  seen on  the issued
stamps from Plates  7,  8,  9 and 10.  Proofs are known:

 a) On paper watermarked Small Crown in mauve-pink, lilac-brown, blue-black.

b) On  similar  paper dipped  in prussiate of potash in blue-black.

c) On white wove paper in deep blue.

d) On white wove paper dipped in prussiate of potash in deep blue.
 
 

 The Second Trial Plate produced twelve impressions instead of three in  the case of the  first trial. The  second  trial
exists  in  three states.  The trial produced impressions  without  the "O" Flaw  and Flaw and  thecorner  letters   were
also voided.    The upper  right corner of  each plate  was by filling  in  the  plate  grooves with  wax.   The three  states
are described  as follows:

State 1:   Proof sheets in this state are known in black, orange-red,  reddish-brown  and  deep  blue.
State 2:  Same as State 1 but  with a tiny  dash  at  the bottom  line of  the  south-east corner square
of the second  stamp  of  the third row.  Proof sheets are known as follows:

a) On white wove paper dipped in prussiate of potash in lilac-pink, lilac- rose, dull rose-red, deep blue.

b) On stout rough white wove paper in black, rose-red, deep blue.

c) On thin white wove paper in bright pink, lilac-rose, dull rose-red, deep rose-red, lilac-brown, deep
red-brown, black, red, blue, deep dull lue, prussian-blue, dull lilac.

d) On thick bluish laid paper (June 1840) in dull red, brownish rose-red, deep rose-red.

 e) A proof in black on paper stained with prussiate of potash,  logwood and cochineal, giving a lilac-
rose tinge to the paper (August 1840).

In State 3 the voided corners are more uniform in shape compared with the ragged corners of the States 1 and 2. Proof
sheets are known as follows:

a) On white wove paper dipped in prusiate of potash in red, red-brown,  rose-red, deep blue, black.

b) On white wove paper in red, pale red, red-brown, crimson red, dull blue, deep blue, prussian blue,
yellow-green, deep green. (See illustred example above).

c) On Small Crown watermarked paper, usually sideways (September 1840),  in red-brown, blue

d) On thick bluish laid  paper  (November 20 1840), in blue, dull blue, green, bluish-green, dark olive-
green, drab.

e) On thick bluish laid paper dipped in prussiate of pot ash (November 1840),  in dark olive-green.