we in some degree force ourselves to suspend our judgment, resting our hope for what is to come upon the undeniable value of what has been already given us. When we formerly treated of this subject, we mentioned the great reliance we placed upon the results of the accurate research and experiments of a friend, P. Rainier, Esq., M.D. of the Albany. It is greatly to be regretted that, at his death, his papers were not properly collected and arranged for use; they are, it is to be feared, lost. We well remember his assertion, that the paint of the old masters invariably vitrified by fire. In proof, he scraped off some paint from an old picture, (it was in the shadow part of back-ground, and not very thick, and where there was not, apparently, any white-lead). He laid it on some platina, and subjected it to the heat of the blow-pipe. The oil first exploded, and the paint was vitrified. Hence, originated the borax medium--remarkable property of which was its capability of being used with water as a diluent or with oil,--thus being a kind of union of the earlier temperas and the oil medium. This borax-glass vehicle was certainly a discovery, or rediscovery, as he was inclined to think it, of our highly valued friend, P. Rainier. We say re-discovery, remembering his playful assumption of a motto, "Veterem revocavit artem." He was probably led to this use of a glass composed of borax, by the vitrification of the pigments; and we still suspect that, in some of the old Italian recipes, glass, with borax as an ingredient, will be found. "_A peculiar kind of Venetian glass_," says Mr Eastlake, "used, when pulverised, as a dryer, contained a considerable portion of lead; and if it acted chemically, may have derived its siccative quality from that ingredient." The question here naturally suggests itself, Why was a peculiar glass used for this purpose, when it was perfectly well known that lead of itself would have been sufficient? Again, in page 358, from the Mayerne MS., as quoting the authority of Mytens; "This oil (mancop) does not dry of itself easily, but it is usually ground with Venetian glass, and thus to the sun in a glass bottle. This should be shaken every four days for three or four weeks: it should then be carefully decanted for use, leaving the sediment with the glass." It is a question if the glass was here solely used to facilitate the sediment.