I found out from him that the Rembrandt was still in our customer’s possession.  The old gentleman had consented to the question of its genuineness being tried, but had far too high an idea of his own knowledge as a connoisseur to incline to the opinion that he had been taken in.  His suspicious relative was not staying in the house, but was in the habit of visiting him, every day, in the forenoon.  That was as much as I wanted to know from others.  The rest depended on myself, on luck, time, human credulity, and a smattering of chemical knowledge which I had acquired in the days of my medical studies.  I left the conclave at the picture-dealer’s forthwith, and purchased at the nearest druggist’s a bottle containing a certain powerful liquid, which I decline to particularize on high moral grounds.  I labeled the bottle “The Amsterdam Cleansing Compound”; and I wrapped round it the following note: 

“Mr. Pickup’s respectful compliments to Mr.—­(let us say, Green).  Is rejoiced to state that he finds himself unexpectedly able to forward Mr. Green’s views relative to the cleaning of ‘The Burgomaster’s Breakfast.’  The inclosed compound has just reached him from Amsterdam.  It is made from a recipe found among the papers of Rembrandt himself—­has been used with the most astonishing results on the Master’s pictures in every gallery of Holland, and is now being applied to the surface of the largest Rembrandt in Mr. P.’s own collection.  Directions for use:  Lay the picture flat, pour the whole contents of the bottle over it gently, so as to flood the entire surface; leave the liquid on the surface for six hours, then wipe it off briskly with a soft cloth of as large a size as can be conveniently used.  The effect will be the most wonderful removal of all dirt, and a complete and brilliant metamorphosis of the present dingy surface of the picture.”

I left this note and the bottle myself at two o’clock that day; then went home, and confidently awaited the result.

The next morning our friend from the office called, announcing himself by a burst of laughter outside the door.  Mr. Green had implicitly followed the directions in the letter the moment he received it—­had allowed the “Amsterdam Cleansing Compound” to remain on the Rembrandt until eight o’clock in the evening—­had called for the softest linen cloth in the whole house—­and had then, with his own venerable hands, carefully wiped off the compound, and with it the whole surface of the picture!  The brown, the black, the Burgomaster, the breakfast, and the ray of yellow light, all came clean off together in considerably less than a minute of time.  If the picture, was brought into court now, the evidence it could give against us was limited to a bit of plain panel, and a mass of black pulp rolled up in a duster.