THE ACTION OF CHEMICAL AFFINITY. 
195 
Meconic Ferric 
acid. chloride. 
Red salt 
produced. 
Meconic 
acid. 
Ferric 
chloride. 
Red salt 
produced. 
1 equiv. -f- 1 equiv. 
88 
1 equiv. -j- 
5 equivs. 
99 
1 equiv. 4-1*2 equiv. 
96 
1 equiv. -f- 
7 equivs. 
93 
1 equiv. + 1*8 equiv. 
108 
1 equiv. + 
9 equivs. 
99 
1 equiv. -j- 2*6 equivs. 
1 equiv. + 3*8 equivs. 
118 
106 
1 equiv. -f 13 equivs. 
119 
These different determinations are exhibited by the continuous line in Plate IX, 
fig. 2 . No regular curve can be described passing through these points ; it is evi- 
dent that there is some action which twice changes the order of the series. 
When ferric sulphate and meconic acid are mixed, it requires about seven atoms of 
the former to five of the latter to produce the greatest intensity of colour. It then 
just about equals in tint the mixture of five atoms of the ferric nitrate with the same 
amount of meconic acid, and made up to the same volume. 
No amount of ferric citrate added to the above-mentioned amount of meconic acid 
is capable of bringing the colour up to that of the former mixtures. This is partly, 
if not wholly, due to the greenish tint of the citrate neutralizing the red of the 
meconate. 
There is then, in the case of the ferric meconate, some action interfering with the 
proper exhibition of the law of mass, which did not occur with the sulphocyanide or 
gallate. It seemed a natural supposition that this might arise from the power of 
meconic acid to form several compounds of different degrees of redness with ferric 
oxide. With a view to ascertain if meconate of iron itself entered into any such com- 
bination with meconic acid, the red salt was prepared by allowing hydrated sesqui- 
oxide to stand some hours with meconic acid. The experiment never gave the result 
anticipated, but this may have arisen from the more acid compound being always 
formed under such circumstances. 
Thinking it would be desirable to repeat these experiments with meconate of 
potash instead of the acid, that salt was prepared by neutralizing meconic acid 
with the carbonate of the alkali. Three atoms of the base were found to combine 
with one of the acid. Single equivalents of this salt and of the various ferric salts 
were mixed. 
1 eq. ferric nitrate + 3 KO, H 4 gave 100 parts of red salt. 
1 eq. ferric chloride + 3KO, C 14 O 14 gave 73 parts of red salt. 
1 eq. ferric sulphate+3KO, C ,4 H 4 gave 84 parts of red salt. 
1 eq. ferric citrate +3X0, Cj 4 H 4 gave a trace of red salt. 
1 eq. ferric acetate +3KO, C 14 H 4 0,4 gave a red precipitate. 
These proportions differ considerably from those observed where meconic acid itself 
was employed. 
The effect of successive additions of meconate of potash to the ferric nitrate was 
also tried. 
2 B 
MDCCCLV. 
