[ 34 ] 
cination the colours are difcharged, but retain a grey- 
ifh call. Several other different fbades of yellow 
anfwered much the fame by my experiments. 
For blue, Mr. Chambers has not as yet ffained 
any marble of that colour. 
By the above experiments we may conclude, that 
thefe colours are good, penetrate the marble freely 
without injuring it, remain uninjured by menftrua, 
&c.', and that only calcination difcharges them. 
Therefore it is probable, that Mr. Chambers’s method 
of flaming or colouring marbles is extremely good. 
Tho’ acid menflrua work greatly on marble, yet 
it is obferv.able thefe colours are not difcharged by 
them, but only by calc. nation ; which, as it intirely 
and thoroughly deffroys the compages of tire done, 
the fubffances of the colours muff undoubtedly at the 
fame time be exhaled by tire force of the fire. We 
obferve a like procefs in the works of nature.; viz . . 
in the dendrites ; I mean, fuch as are on alealine 
ffor.es : for tiro’ the ffones are utterly corroded by 
the acids, yet the dendritoe, however merely fuper- 
fkial, remain ; but if calcined, the faid dendritar are 
immediately exhaled, and intirely difappear. 
This art will not only give pleafure to the eve by 
regular paintings (whereas the natural colourings of 
marble are very irregular), but it may be very ufeful 
to blazon arms, and for inferiptions ; as fculpture 
alone can never exprefs colours, and chiffefd inferip- 
tions, &c. fuffer much by age : for probably a mo- 
nument of marble, rightly coloured by this method, 
will be preferved ages from the injuries of the weather, 
tho* 
