Isn't there some story about a picture of Reynolds' in which bitumen had been used?
A portrait of a lady, I think.

The bitumen softened, and one of the lady's eyes slipped down on to her cheek; and they had to hang the portrait upside down and keep it warm until the eye slipped back into its place.

But what was your question ?" "I was wondering whether the bitumen used by the Egyptian artists has ever been known to soften after this great lapse of time." "Yes, I think it has.

I have heard of instances in which the bitumen coatings of mummy cases have softened under certain circumstances and become quite 'tacky.' But, bless my soul! here am I gossiping with you and wasting your time, and it is nearly a quarter to nine!" My guest rose hastily, and I, with many apologies for having detained him, proceeded to fulfil my promise to guide him to his destination.

As we sallied forth together the glamour of Egypt faded by degrees, and when he shook my hand stiffly at the gate of the Bellinghams' house, all his vivacity and enthusiasm had vanished, leaving the taciturn lawyer, dry, uncommunicative, and not a little suspicious..