THE ACTION OF CHEMICAL AFFINITY. 
187 
But the original 880 gr. meas. expressed the amount of ferric sulphocyanide produced 
by the mixture of one equiv, of ferric nitrate and three equivs. of sulphocyanide of 
potassium. Every addition also of 6'25 gr. meas. of sulphocyanide of potassium is an 
addition of three equivalents. Hence the first line of the preceding Table signifies that, 
considering the amount of the aforesaid ferric sulphocyanide as 880 (or for greater 
convenience 88), the amount formed when the same one equivalent of ferric nitrate 
is mixed with six equivalents of sulphocyanide of potassium is 880+390, that is 1270 
(or 127)*. On this principle the foregoing experimental results may be thus tabu- 
lated : — 
Ferric nitrate. Si^lphocyan. of 
potassium. 
Red salt 
produced. 
Ferric nitrate. Sulphocyan. of 
potassium. 
Red salt 
produced. 
1 equiv. -j- 3 equivs. 
88 
1 equiv.-)- 63 equivs. 
356 
1 equiv. 6 equivs. 
127 
1 equiv. -f 99 equivs. 
419 
1 equiv. -|- 9‘6 equivs. 
156 
1 equiv.-)- 135 equivs. 
457 
1 equiv.-)- 12‘6 equivs. 
176 
1 equiv.-)- 189 equivs. 
508 
1 equiv. -f 16'2 equivs 
195 
1 equiv.-)- 243 equivs. 
539 
1 equiv. -j- 19‘2 equivs. 
213 
1 equiv.-f 297 equivs. 
560 
1 equiv.-)- 28*2 equivs. 
1 equiv.-)- 46*2 equivs. 
266 
318 
1 equiv ,-)- 375 equivs. 
587 
On comparing these numbers, it will be at once evident that each addition of the 
sulphocyanide produced relatively a smaller increase of colour. The numbers in fact 
give the long curve of Plate VII. fig. 1, where the ordinates express the proportionate 
amount of red salt, and the abscissae the number of equivalents of the sulphocyanide. 
The influence of mass was again tried by means of additional portions of ferric 
nitrate instead of additional sulphocyanide of potassium. The experiment was con- 
ducted in a precisely similar manner to the last. I have not thought it necessary to 
record the amounts of the salts and the water employed : the following are the results 
of the observations reduced as before ; — 
Sulphocyan. of 
potassium. 
Red salt 
produced. 
Sulphocyan. of 
potassium. 
Red salt 
produced. 
3 equivs.-)-! equiv. 
88 
3 equivs. + 5 equivs. 
138 
3 equivs.-)- 2 equivs. 
110-5 
3 equivs.-)- 6 equivs. 
144 
3 equivs. -)- 3 equivs. 
122 
3 equivs.-)- 10 equivs. 
161 
3 equivs. + 4 equivs. 
131 
3 equivs.-)- 14 equivs. 
174 
These numbers also give a curve. It is that designed in Plate VII. fig. 11. 
It is not difficult to bring this experiment into uniformity with the preceding so as 
to form in fact a continuation of it, one equiv. of ferric nitrate being combined with 
less than three equivs. of sulphocyanide of potassium. For, expressing the number 
of equivalents of the iron salt by x, and the comparative amount of ferric sulphocy- 
anide by y, the general formula of the terms in the above Table will be, K denoting 
the potassium and F the iron salt, — 
3K+a;F=3/, 
MDCCCLV. 
* See Note A. 
2 D 
