- No. 4, again changes to stout.
- Nos. 1 and 2 mixed equal stout.
- Nos. 3 and 4 mixed equal water.
- Nos. 1 and 2 put back into the jug give all stout.
- Nos. 3 and 4 put back into the jug give all water, as at first.
The explanation, although by no means obvious, is very simple. Glass No. 1 is perfectly clean. No. 2 contains a small portion of pyrogallic acid, about the size of a pea. No. 3 is prepared with half a teaspoonful of sulphuric acid. No. 4 contains the same quantity of pyrogallic acid as No. 2. The jug contains clear water, into which a teaspoonful of sulphate of iron is dropped just before the trick is commenced. The iron should not be placed in the water until actually required for use, as the solution changes rapidly to a yellow color, in which condition it would not very well pass for water. For the same reason the jug should be removed immediately after the trick.
Some performers prefer to use the following chemicals in place of those enumerated above. I will give them in the same order, and then the magician may choose for himself. Glass No. 1, as before, is quite clean; No. 2 contains a few
