VOL. XLIX.] PHILOSOPHICAL TRANSACTIONS. S-, 



taken to explain an obscure passage in Pliny the naturalist. This author says in 

 some place of his works, that " the ancients painted with burnt wax ;" and we 

 have it from tradition, that pictures of this kind were very durable. This was 

 the passage, that the count undertook to clear up, by trying all the different 

 ways possible to paint in wax ; and after many experiments he hit upon a very 

 simple method, of which he made a secret, in order to excite the curiosity of 

 the public. For that time he only thought proper to show one picture at the 

 Louvre, representing the head of Minerva, painted in the manner of the an- 

 cients, and which was much admired. 



The several artists, who were desirous of knowing by what means the count 

 came to make this discovery, made several attempts themselves ; but in a great 

 number of trials, only 2 are worth mentioning. 



The first was to melt wax and oil of turpentine together, and use it for mixing 

 the colours. But this method does not at all explain Pliny's meaning, because 

 wax is not burnt in this way of managing it : and besides, this method has two 

 defects ; the oil of turpentine dries too fast, and does not allow the painter suf- 

 ficient time to blend and unite his colours. The 2d method is very ingenious, 

 and seems to come up to Pliny's notion very well : it is as follows : the wax is 

 melted with strong lixivium of salt of tartar, and with this the colours are ground. 

 When the picture is finished, it is gradually put to the fire, which increases the 

 heat by degrees ; the wax melts, swells, and is bloated up upon the picture : 

 then the picture is removed gradually from the fire, and the colours do not at all 

 appear to have been disordered : the colours then become unalterable by the 

 action of the air, and even spirit of wine has been burnt upon them without 

 doing them the least harm. 



However, the following is the Count de Caylus's method, which is much more 

 simple; according to which the head of Minerva was painted, which was so 

 much admired by all the connoisseurs. 1st. The cloth or wood, designed for 

 the picture, is waxed over, by only rubbing it simply with a piece of bees-wax. 

 2dly, The colours are mixed up with common water ; but as these colours will 

 not adhere to the wax, the whole picture is to be first rubbed over with the 

 Spanish white, and then the colours are used. 3dly, When the picture is dry, 

 it is put near the fire, by which the wax melts, and absorbs all the colours. 



The effect produced by these colours upon wax is very singular ; nor can one 

 have any notion of it without seeing it. The colours have not that natural 

 varnish or shining that they acquire with oil ; but you are capable of seeing the 

 picture in any light, or in whatever situation you place it : in short there can be 

 no false glare or light on the picture for the spectators : the colours are secured, 

 are firm, and will bear washing ; and have a property, that they have smoked 

 this picture in places subject to foul vapours, and to smoke in chimnies ; and then 

 by being exposed to the dew, it became as clean as if it had been but just painted. 



