- vapo


amber in a crucible till it becomes black, and then diflolving this black fubltance, firfi reduced to a powder, in linfeed-oil, orin a mix- ture oflinfced oil and oil ofturpen- tine-By melting the amber in this prccefs, it fuffers a decom- pofition, its nature is changed, and part of its oily and faline matter is expelled. The fame changes oc- cur in the common dillillation of this fubjeét: and when the dillil- lation is not pufhed too far, the ihining black mafs which remains after the thinner oil and greater part of the falt have arifen, is in fuch a proportion folnble in oils, as to (apply the common demand of the varnifh-makers-This de- cotnpolition, however, is not necef- fary, as has generally been fuppofed, in order to the folution : from the curious experiments of Holiman, Stockar, Zeigler, and others, it ap- pears, that amber may be perfectly diflblved, in expreffed oils, in tur- pentine, and in balfam of copaiba, ifit be expofed to the action of thefe menftrua in clofe fiopt velTels, and afiified by a due degree ofheat. —-The folution may-be more expe- ditioully made, if the fire be f0 firong as to convert part of the oil ‘into elaftic vapours; care mnPt be taken to give fuch a vent to thofe urs, as not to endanger the burfiing of the velfel.

The folution,” fays Dr. Lewis, in rapefeed-oil, and in oil of al- monds, was of a fine yellowilh co- lour; in linfeed-oil, gold-colour- ed; in oil of poppy-feeds, yellow-


ilh red; in oil-olive, of a beau- tiful red; in oil of nuts, deeper- coloured; and in oil of bays, of a purple red. It is obfervable, that this lalt oil, which of itfelf, in the greatelt common heat of the at- mofphere, proves of a thick bu- tyraceous confidence, continued fluid when the amber was dilTolved in it. The folutions made with turpentine, and with balfam ofco- paiba, were of a deep red colour, and on cooling hardened into a brittle mafs of the fame colour. All the folutions mingled perfeftly with fpirit of turpentine. Thole made with the oils of linfeed, bays, poppy-{eedg-and with nuts, and with balfam of copaiba and tur- pentine, being diluted with four times their quantity of fpirit of turpentine, formed hard, tenacious gloliy varniihes, which dried fut"- ficiently quick, and appeared great- ly preferable to thofe made in the common manner, from melted amber.”


LACK feeling-wax is com- pofed of gum-lac *, melted with one half or one third ofits weight ofivory-black in fine pow- der. The inferior fort of lac, called {hell lac, anfsvers as well for this ufe as the fineft. l: is cufiomary to mix with it, for the tirdinary kinds of fealing-tvax’, a contidcrable pro- p0rtion,as two-thirds its weight, of the cheaper relinous bodies, particu- larly Venice turpentine, by which

' More properly called Stick Ia:.---Lac is a concrete brittle fubllanre, fail to be collected from certain trees by a winged red meet, and depolizetl either an the branches of the trees or on {ticks fixed in the earth for that purpvft . \Vnen

freed from thetinging matter it receives from the young izziluts, it 1S rt‘ Enter-

mediate nature between wax and relins.