THE ACTION OF CHEMICAL AFFINITY. 
197 
Another solution of meconate of iron was similarly treated with dilute hydrochloric 
acid : — 
Hydrochloric 
acid added. 
j 1,1 • Water added to 
Hytochloric comparative 
acid added. . 
2 measures = 3*6 measures. 
3 measures = 5 measures. 
5 measures =10 measures. 
7 measures = 15 measures. 
9 measures = 20 measures. 
It is evident, that although a reduction of the amount of ferric meconate always 
takes place, there is some cause interfering with the regularity of the decrease of 
colour. 
The amount of ferric meconate depends therefore upon the nature and upon the 
quantity of all the substances present at the same time in the solution ; but the regu- 
larity of the action of mass, which was observed with the sulphocyanide and gallate, 
is not confirmed in this instance. 
Ferric Pyromeconate. 
Thinking that the irregularity in the influence of mass might be more or less con- 
nected with the tribasic character of meconic acid, it occurred to me that an exami- 
nation of ferric pyromeconate would be desirable, since pyromeconic acid is mono- 
basic, and yet strikes an intense red with the sesquioxide of iron, and in many other 
respects resembles the substance from which it is derived. Accordingly, some pyro- 
meconic acid was prepared by submitting meconic acid to dry distillation : — 
% 
1 eq. ferric nitrate -j- 3 eq. pyromeconic acid gave 100 parts of red salt. 
1 eq. ferric chloride + 3 eq. pyromeconic acid gave 86 parts of red salt. 
1 eq. ferric sulphate -}- 3 eq. pyromeconic acid gave 39 parts of red salt. 
1 eq. ferric citrate + 3 eq. pyromeconic acid gave 27 parts of red salt. 
1 eq. ferric acetate + 3 eq. pyromeconic acid gave a red precipitate. 
1 eq. ferric nitrate + 3 eq. pyromeconate of potash gave 100 parts of red salt. 
1 eq. ferric chloride -f 3 eq. pyromeconate of potash gave 74 parts of red salt. 
1 eq. ferric sulphate -}- 3 eq. pyromeconate of potash gave 36 parts of red salt. 
1 eq. ferric citrate -f- 3 eq. pyromeconate of potash gave 26 parts of red salt. 
1 eq. ferric acetate + 3 eq. pyromeconate of potash gave a red precipitate. 
On trying the influence of mass, it was found that the addition of pyromeconic acid 
rapidly diminished the colour of ferric pyromeconate ; and that the colour was the 
deepest when the base was in large excess. 
Thinking that the effect of a colourless salt upon the red pyromeconate might dis- 
play more clearly the influence of mass, a mixture of ferric chloride and pyromeconic 
acid was experimented on with a solution of sulphate of potash 
2 E 2 
