OX PAINTING WITH MILK. 0\j 



By examining, in the fame manner, the effect of the addi- The oil is of no 

 tion of oil upon the reft of the mixture, we foon perceive ™^ s t * nin " 

 that if it does not improvethe folidity of the colour, it mufl° 

 either be ufelefs or pernicious ; becaufe it renders the tint 

 dull, and communicates a difagreeable fmell. Now experi- 

 ment demonftrates the negative, for milk paint In diftemper 

 does not refift water more than the fimple mixture of lkimmed 

 milk with flaked lime and whiting. 



I have alfo concluded that the quantity of fix ounces, or The proportion 

 183,430 grains of flaked lime, prefcribed in the recipe for °™ me is t0 ° 

 painting in diftemper with milk, was much too cOrifiderable, 

 becaufe two ounces, or 61,143 grammes, or even a fmaller 

 quantity, is fufficient entirely to liquify one French pint, or 

 or 951,206 cubic centimeters of lkimmed milk. The pellicle 

 of calcareous carbonate, which is formed after a time at the 

 furface of painting in milk diftemper, fhews, as well as other 

 experiments on this fubject, that the prefent obfervations are 

 well founded. 



With regard to the whiting, I think the dofe may be in- The whiting 

 creafed without inconvenience. Cadet-de-Vaux already added may beincrcafea. 

 three pounds, Or 1467,438 grammes, to five pounds, or 

 2445,75 grammes. I have gone further, and have ufed a 

 dofe of eight pounds, or 3913,168 grammes, and the colour 

 I obtained did not appear to me lefs folid than that made ac- 

 cording to the original recipe. This obfervation does not 

 apply to the preparation, when required to be coloured either 

 by an ocre, an earth, or an oxide. I have remarked, that 

 thefe fubftances require more of the mordant than the whiting 

 does ; and this happens, in fact, with painting in diftemper 

 with milk coloured yellow or red, in Order to be applied to 

 pannels, &c. namely, that the addition of thefe colouring 

 matters deprive it of all its folidity. We mull not, therefore, Colour muft be 



add the colour to the paint entirely mixed, as is directed at * dded during the 



~.~ r .i • i .. . .- _i , r r ,..',. nrft mixture, 



page 248 ot the memoir, but diminifh the dole of whitm£ m 



proportion to the quantity of colouring matter necefTary to 

 produce the required tint ; in a word, it is requifite that the 

 colouring matters added to the whiting fliould not weigh at 

 moft more than the five pounds, or 244,573 grammes pre- 

 fcribed in the recipe. 



Thefe are the principal obfervations I have made on paint- 

 ing in milk ; let us now fee what are the confequence 

 we may juflly derive from them. 



I have 



