194 
DR. GLADSTONE ON CIRCUMSTANCES MODIFYING 
Ferric gallate was prepared by dissolving the hydrated sesquioxide of iron in gallic 
acid. It was divided into two equal parts, to one of which successive portions of 
hydrochloric acid were added, while the other was diluted after each addition till it 
had been reduced to the colour of the acid mixture. 
,, , , , . Water added to 
Hydrochloric comparative 
acid added. 
TT j 1.1 • Water added to 
Hydrochlonc .. 
11 j comparative 
acid added. { . . 
solution. 
1 measure = 3’4 measures. 
3 measures = 6‘6 measures. 
3’25 measures = lO’l measures. 
4*5 measures = 12‘0 measures. 
It requires no further experiments to show that the ferric gallate bears the same 
testimony as the sulphocyanide. 
Ferric Meconate. 
Similar experiments were made with meconic acid and the iron salts. After mixing 
these substances it was found necessary to allow the solutions to stand a minute or 
two before observation, in order that the full colour might be developed. 
1 eq. ferric nitrate +1 eq. meconic acid (3HO, C 14 H 4 0 i 4 ) gave 100 parts of red salt. 
I eq. ferric chloride + 1 eq. meconic acid (3HO, Ci 4 H 4 0 i 4 ) gave 96 parts of red salt. 
1 eq. ferric sulphate+1 eq. meconic acid (3110, Cj 4 H 4 0 i 4 ) gave 72 parts of red salt. 
1 eq. ferric citrate +1 eq. meconic acid (3HO, C 14 1140 , 4 ) gave 42 parts of red salt. 
1 eq. ferric acetate +1 eq. meconic acid (3HO, 0,4 H 4 0 , 4 ) gave a red precipitate. 
The influence of successive additions of meconic acid to a mixture of single equiva- 
lents of that substance and ferric nitrate was tried. The results were as follows ; — 
Ferric Meconic 
nitrate. acid. 
Red salt 
produced. 
Ferric Meconic 
nitrate. acid. 
Red salt 
produced. 
1 equiv. + 1 equiv. 
88 
1 equiv. + 4 equivs. 
75 
1 equiv. + 2 equivs. 
80 
1 equiv. -}- 6 equivs. 
73 
1 equiv. + 3 equivs. 
76 
1 equiv. + 8 equivs. 
74 
Here, instead of finding an increase of colour, as might have been expected by 
analogy, there is a distinct though small decrease. On examining the action more 
fully, and by repeated experiments, it was found that the maximum colour was 
obtained when the ferric nitrate and the meconic acid were mixed in single equiva- 
lents (or rather in the proportion of 12 atoms of the former to 11 of the latter); that 
the addition of more ferric nitrate to such a mixture did not notably increase the 
colour ; that the addition to it of 0’25 equivalent of meconic acid made little change ; 
and that a greater addition caused a decided diminution of the tint. 
A mixture of one equivalent of meconic acid with one equivalent of sesquichloride of 
iron was examined in a similar manner. The addition of meconic acid was found in 
this case also to diminish the colour. The effect of successive additions of the ferric 
salt was more partieularly tried. 
