THE ACTION OF CHEMICAL AFFINITY. 
207 
Sulphate of Hydrochloric 
copper solution. acid solution. 
I. 
II. 
III. 
IV. 
50 measures + 10 measures. 
50 measures + 12’5 measures. 
50 measures+ 15 measures. 
50 measures + 20 measures. 
50 measures + 30 measures. 
50 measures + 40 measures. 
50 measures + 50 measures. 
50 measures + 70 measures. 
Perfectly blue. 
Greenish blue. 
Distinctly green. 
Clear green. 
Bright green. 
Bright green. 
Brighter green. 
Still brighter. 
Perfectly blue. 
Blue. 
Blue, with trace of green. 
Just a shade greener. 
Dull bluish green. 
SeenV"^'’""*y 
GreenJ g^^^hable. 
1-1 
C 
a c3 
£ ^ 
3 <V 
0) 
^153 
Pure blue. 
Pure blue. 
Pure blue. 
Pure blue. 
Pure blue. 
Blue, with a trace of green. 
Blue, with a trace of green. 
Blue, with a trace of green. 
It is not to be infetred that the sulphate of copper was in larger quantity in 
column IV. than in column I., for water acts according to its mass upon pure chlo- 
ride of copper, converting it from a green into a blue compound. For some time I 
imagined that the changes of colour in the preceding mixtures of sulphate of copper 
and hydrochloric acid did not take place in regular gradation, but that something 
occurred analogous to what Bunsen discovered in his experiments ; yet, after repeated 
endeavours to fix the apparent points of transition, I arrived at the conclusion that 
they might arise merely from the great difficulty of comparing greens of different 
characters. 
To seven portions of the standard solution of sulphate of copper, each measuring 
.50 parts, were added respectively 10, 20, 30, 40, 50, 70, and 100 parts of a saturated 
solution of chloride of sodium. There resulted a series of tints passing gradually 
from blue to almost pure green, without any sudden transition. 
A strong solution of chloride of zinc added to a solution of sulphate of copper also 
produced a greenish colour, which increased as more chloride was added. 
Knowing the disposition of oxide of lead and acetic acid to combine, it occurred 
to me that chloride of lead might decompose the acetate of copper very readily. 
Accordingly, two equal portions of the blue acetate were mixed with equivalent 
amounts of chloride of lead and chloride of sodium in solution ; and it was indeed 
found that the former caused a greater diminution of the colour than the latter did. 
In this experiment much water was necessarily employed, but chloride of copper 
always gives a far paler blue solution than an equivalent amount of the acetate does. 
These reactions with copper salts bear additional testimony, therefore, to the truth 
of the previous views *. 
Molybdous salts. 
As the molybdous fluoride gives a purple, and the chloride a green solution, these 
salts offered another means of testing whether complete or partial decomposition 
ensued on the mixing of binary compounds. Molybdous oxide was dissolved in 
hydrofluoric acid, and the resulting purple solution was treated with hydrochloric 
acid. It changed gradually to a greenish blue; and, on adding more hydrochloric 
acid, to a positive green. Time entered as an appreciable element into this change. 
* See Note D. 
