though a saponaceous medium, it was not again soluble in water. What does Vasari mean by "che accende i colori"--"which heightens the colours?" Borax is an alkali. Alkalis are known to heighten colours, "e gli fa lucidi;" now, linseed and nut oil _alone_, particularly the former, takes away the _lucid_ character from paint. Had Vasari been describing the working of this vehicle of P. Rainier, he could not have better described it than in the very words "gli unisce mirabilmente;" for it is astonishing how nicely to the hand, and to the degrees desired, these repugnant liquids unite the colours. It is singular enough that soda, which is a form of borax, is the actual constituent part of some of our most permanent colours--we need but mention ultramarine; and here we are tempted to transcribe a passage from the translator's preface, which exactly falls in with this our view.--"The use made by the early Italian artists of lyes (lisciva) is deserving of our notice and consideration. Cennino does not inform us how this lye was prepared; but it has been ascertained that lyes produced from pouring water on wood-ashes, from solutions of borax, and also of soda in water, were then used. We find from Cennino's book that ultramarine (of which soda is a constituent part) was prepared with it; that it was also used in preparing _azzuro della magna_, (an ore of cobalt,) and _zafferano_. It has been likewise ascertained that soda has a preserving influence on red, yellow, and black pigments; and the result of experiments on these colours has been so satisfactory, that a certain quantity of soda--or, to speak more correctly, of _soap_, which is a compound of soda with fat or oil, (but not drying oil)--is now used in preparing pigments for painting sails for the British navy. It is also used in the manufacture of printing-ink; and we have now Cennino's authority for using it with _blue_ pigments. Sir Humphrey Davy informs us, that the Vestorian or Egyptian azure, the excellence of which is proved by its duration of 1700 years, may be easily imitated by carbonate of soda, opaque flint, and copper filings. The translator has made many experiments on the effect of the alkalis and neutral salts when mixed with colours, and has every reason to be satisfied with the addition of soda, when properly used." We have not ourselves tried sufficiently soda with oil, and have suspected it would not have the effect of rendering the paint hard; but that borax does render the paint very hard we have abundant proof. We have subjected a picture painted with it to the razor to scrape it down, and could with difficulty succeed, though the picture had not been long painted; and we have rolled together masses of paint so mixed, and they have been thought by persons into whose hands we have put them, stone. We have heard artists, who have tried this mixture of borax and oil, declare it had the contrary effect; but, on enquiry, found that they procured the vehicle