| Sulphate of lead | 19 |
| Nitrate of soda | 10·75 |
| 29·75 |
We see that the absolute weights of the two sets of salts are the same: all that has happened is, that both the acids and both the bases have exchanged situations. Now if, instead of mixing these two salts together in the preceding proportions, we employ
| Sulphate of soda | 9 |
| Nitrate of lead | 25·75 |
That is to say, if we employ 5 parts of nitrate of lead more than is sufficient for the purpose; we shall have exactly the same decompositions as before; but the 5 of excess of nitrate of lead will remain in solution, mixed with the nitrate of soda. There will be precipitated as before,
Sulphate of lead 19
and there will remain in solution a mixture of
| Nitrate of soda | 10·75 |
| Nitrate of lead | 5 |
The phenomena are precisely the same as before; the additional 5 of nitrate of lead have occasioned no alteration; the decomposition has gone on just as if they had not been present.
Now the phenomena which drew the particular attention of Wenzel is, that if the salts were neutral before being mixed, the neutrality was not affected by the decomposition which took place on their mixture.[7] A salt is said to be neutral when it neither possesses the characters of an acid or an alkali. Acids redden vegetable blues, while alkalies render them green. A neutral salt produces no effect whatever upon vegetable blues. This observation of Wenzel is very important: it is obvious that the salts, after their decomposition, could not have remained neutral unless the elements of the two salts had been such that the bases in each just saturated the acids in either of the salts.
The constituents of the two salts are as follows: