196 
DR. GLADSTONE ON CIRCUMSTANCES MODIFYING 
Ferric Meconate 
nitrate. of potash. 
Red salt 
produced. 
Ferric Meconate 
nitrate. of potash. 
Red salt 
produced. 
1 equiv. + 0*33 equiv. 
34 
1 equiv. + 1 equiv. 
88 
1 equiv. + 0’5 equiv. 
50 
1 equiv. + 1’2 equiv. 
84 
1 equiv. + 0’8 equiv. 
74 
1 equiv. + 1*5 equiv. 
69 . 
Here the greatest intensity of colour evidently occurs when about single equivalents 
are mixed, the addition of a larger quantity of meconate of potash producing a rapid 
diminution of the colour. 
The same was observed in respect to the ferric chloride. When single equivalents had 
been mixed, the addition of more ferric salt was not found to make any great difference 
in colour. This action, however, was examined quantitatively by means of the citrate. 
Meconate Ferric 
of potash. citrate. 
Red salt 
produced. 
Meconate Ferric 
of potash. citrate. 
Red salt 
produced. 
1 equiv. + 0*8 equiv. 
97 
1 equiv. + 3-8 equivs. 
' 102 
1 equiv. + 1*2 equiv. 
80 
1 equiv. + 5 equivs. 
125 
1 equiv. + 1*8 equiv. 
69 
1 equiv. + 7 equivs. 
154 
1 equiv. + 2*6 equivs. 
74 
1 equiv. + 9‘2 equivs. 
165 
These numbers are represented by the broken line in Plate IX. fig. 2. 
Imagining that the rapid decrease of colour manifested when meconate of potash 
was added in excess to the ferric salt, might be due to the formation of some paler 
double compound, I added the potash salt to a solution of pure meconate. The 
colour was greatly diminished. 
These results show satisfactorily enough that the amount of meconate of iron formed 
depends upon the nature of the various substances in solution, but their testimony in 
respect to the mass of these substances is obscured by the formation of these double 
compounds. Thinking to avoid this by always using the same amount of meconic 
acid and iron, and yet to exhibit the effect of mass, the following experiments were 
performed. Pure meconate of iron was treated with acetate of potash ; it was quickly 
reduced to a pale yellow. Oxalate or phosphate of potash had the same effect. A 
saturated solution of sulphate of potash was tried, and gave these results: — 
Sulphate of 
potash added. 
Water added to 
comparative 
solution. 
5 measures = 12 measures. 
12 measures = 30 measures. 
A strong solution of sulphate of soda was tried : — 
c- T T_ X £ Water added to 
Sulphate of 
sodi added. “XSr 
Sulphate of 
sodLdded. comparative 
solution. 
5 measures = 16 measures. 
1 0 measures = 26 measures, 
20 measures = 36 measures. 
40 measures = 58 measures. 
60 measures = 80 measures. 
