from colour-makers, who sold them, we have good grounds for believing, a mixture of their own, in which, if borax formed any part, mastic varnish formed a much larger. Among our papers we found one sent us by Dr Rainier; we were not chemists enough to make it intelligible, and for that recipe which we give in a note,[6] we are indebted to our friend Mr C. T. Coathupe of Bristol, on whose chemical and general scientific knowledge we have great reliance, and who much confirmed our view, or rather Rainier's, of the advantage of rendering the oils saponaceous by the means of borax. In consequence of our communication with him, Mr Coathupe published in the _Art Union_ one or two very valuable papers in 1842. In speaking of this vehicle we do so the more boldly as it is not our own, nor do we claim the least merit on account of it; it is solely the discovery, or re-discovery, be it which it may, of our ever valued friend Rainier, now no more. Without saying that it is or is not _the_ old one, "che tutti i pittori del mondo aveano lungamente desiderata," we do not hesitate to say that it is a good one, and does obviate those "oily appearances so disagreeable to the eye"; and we are the more confirmed in our belief in its beneficial quality, by the authorities Mr Coathupe and Mr Field, the well-known scientific author of "chromatography;" and we are much gratified to be able to offer an extract from a letter from Mr Field upon the subject:--"I am accordingly ready to admit all the uses of Mr Rainier's medium, and go with him in believing the old painters may have employed it--the Venetians in particular, who were at that time the medium between Europe and India, in the latter of which countries borax had been employed in painting time immemorial." It should here be remarked that Mr Field, in one of his valuable publications, mentions a mixture of lac and oil by means of borax in certain proportions. They do not, however, readily mix, especially in cold weather. The translator does not seem to be aware that borax is the solvent for lac; she mentions "sulphuric or muriatic acid," but water with borax alone will dissolve lac before it boils.[7] We would venture to recommend some experiments with lac dissolved in borax to water-colour painters. It is by no means improbable that some of the old Greek paintings are in gum lac; the hardness ascribed to them, and their brilliancy too, and that they rather chip off than crack, seem to answer the properties of lac; and it is curious that lac so dissolved is durable, and not again soluble in water. It _may_ therefore be worth while to try experiments with it, both for solid painting with white lead, as likewise as an addition of power partially used for water-colours. We know not if the ancients had any means of discharging the colour, (though a weak solution, in cases of solid painting, may not be very objectional,) but shell-lac can now be rendered perfectly white.