I propose in the Academy to put Roberson's medium over the whole of my large one and to retouch with the same. A portrait on to which I _don't_ intend to work I should cover with mastic and _a little poppy oil_; there is no harm in this, I suppose, and the small quantity of mastic is not likely to yellow, is it? I know this mixture _won't come off_, but why should it? * * * * * _May 30, 1889._ Messrs. Reeves send me a colour in which I delight, but which I have hitherto always avoided as being unsafe, to wit, indigo. I suppose one ought not to use it, ought one? although my old friend, and in some ways my master, Robert Fleury, employed it extensively in _underpainting_ blue draperies. * * * * * _December 23, 1889._ I have got a recipe--a very simple one--from a friend of mine in Italy, who paints a good deal in distemper, and who in technical matters is quite the most leery person I ever came across. In this recipe he mentions what he calls "Gum Damar," which he, in his characteristic ignorance of spelling (for Italians are not very strong in orthography), writes with an apostrophe, D'Amar. Now I presume he means "Gum Dammar" (I believe there is such a thing, is there not?), but I should like to feel sure. Perhaps you will kindly enlighten me on a post-card. The distemper itself is the simplest thing in the world. It is only a proportion of water and yolk of egg (he deprecates the use of vinegar), to which he adds a certain number of drops (I have not the recipe by me) of this gum. Of course it would be important not to use the wrong gum. Hence the trouble I am giving you. * * * * * _January 27, 1890._ I have just received from Perugia the enclosed sample of Gum Dammar, which you were kind enough to say that you would report upon to me. A few drops of this (by-the-bye, I do not know how it is to be dissolved) and the yolk of an egg stirred in water, form the distemper used by my friend Mariani. I don't know whether I told you that he is rather an interesting fellow. He is one of those extremely dexterous Italian workmen-artists who know and can work in every material, and whose forgeries of sixteenth century bric-à-brac, cassoni, reliefs in pastiglia, &c. &c., have, I am afraid, not infrequently been purchased as original by very crafty persons.