52 Prof. Hausmann on the Composition of the Ancient 
produced by a sublimation of the pigments. The black var- 
nish is sometimes covered over by a white exhalation whea 
burnt, the production of which may perhaps be explained from 
the decomposition of its substance. More accurate investiga- 
tion, however, has shown me, that the white colour arises from 
the burning of the calcareous particles intimately conjoined with 
the surface of the vases, and cannot be ascribed to the ashes of 
the varnish. 
Erom an accurate examination it appears probable, that the 
thin pellucid coating, by which the colour of the clay is render- 
ed brighter or duller, is of the same substance with the black 
paint of vases, but in a diluted or extenuated state, which was 
first shewn by the celebrated Jorio , the very learned Inspector 
of the Royal Collection of Vases at Naples * * * § . It may common- 
ly be observed in vases, that this paint has been repeatedly ap- 
plied, where the colour of the clay had not been completely mo- 
dified by the first operation, and in this manner also the colour 
has been changed from dusky to black *f\ Sometimes single 
lines occur, in which different degrees of intensity may be ob- 
served in the colour. 
We shall now inquire into the nature of this black paint. 
Caylus has ascribed the black varnish to the martial or manga- 
nesian earth of glass-works J, an opinion which Grivaud has also 
embraced ||. Le Sage once thought, that the black coating of 
vases was produced from oxide of lead and oxide of manganese §, 
which opinion is not only sufficiently confuted by what I have 
said above, with regard to the nature of the varnish, but also by 
the slight degree of baking which the vases have undergone, by 
which the oxide of lead could not be applied, as CJiaptal has 
also remarked Scheerer says, that the coating of vases does 
not consist of metallic substances, but of a certain kind of earth, 
and that the black colour cannot have been produced by oxide 
of manganese. Chaptal inclines to the opinion, that vitreous 
* Sul. Met. d. Ant. nel Dipingere i Vasi, p. 5. 
■f* Jorio , loc. cit. p. 10. $ Rec. d’Antiq. t. i, p. 87. 
|| Esame di alcune pietre impiegate per fare vasellarai. Brugnatetti Annali 
di Chimica, t. iii. p. 151. 
§ Mem. de 1’Inst. 1808, p. 335. 
Boettiger's Vasengemalde, Bo. ii. Heft, 2, p. 35, 36. 
