54 Prof. Hausmann on the Composition of the Ancient 
laid on and burnt in, in the same way as the pigments are in 
the manufacture of our better sorts of earthen-ware. I applied 
various carbonaceous substances, vegetable as well as mineral, 
reduced to a sufficient degree of tenuity by levigation, either by 
themselves or by means of a fluid, or mixed with fusible sub- 
stances, to vessels either dried in the air or baked, and these I 
exposed, after inclosing them in other vessels, to various degrees 
of heat in a potteiy-furnace. These vessels so coated, came, 
without exception, from the furnace, with red, yellow or white 
colours, according to the quality of the clay, and the different 
degrees of heat. I applied liquid bitumen in other experiments, 
but with no better success. 
When I had almost despaired of accomplishing my object, it 
occurred to me, that perhaps the method which is used for 
covering iron-work with a black coating, might be equally ap- 
plied to earthen-ware. The experiments in which I made use 
of mineral bitumen succeeded very well. I dissolved asphaltum 
in naphtha or mineral oil, and applied the solution, by means of 
a pencil, to earthen-vessels once baked and again heated, by 
which a black coating like varnish, intimately attached to the 
surface of the vessels, and precisely similar in appearance to the 
black coating of the ancient Grecian vases, was immediately pro- 
duced. The degree of heat at which the solution is to be ap- 
plied, should be such as is sufficient for melting the asphaltum. 
I exposed the vessels, after the coating was laid on, for some 
time to heat, by which the naphtha is evaporated, and the var- 
nish is completely dried. Liquid bitumen applied in the same 
manner, gives a similar but less bright varnish. The solution 
of asphaltum by means of naphtha , is also preferable on this ac- 
count, that very different degrees of saturation may be produced. 
A thin solution affords a transparent varnish, by which dusky 
colours are produced, passing more or less into red, according 
to the different colour of the clay. If the application of this so- 
lution be repeated, very different varieties of varnish may be 
produced, from a brown colour to a perfect black. If a satu- 
rated solution be applied, a dull black colour is produced at 
once. 
In the same way that the surface of vessels is covered over 
with varnish, various figures are painted upon it by means of a 
