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The whole page is taken up with recipes for varnishes:
Thick Amber Varnish a dark brown color
½ a lb of Amber over a gentle fire in an Iron pot | cover a small hole in it until melted. taken off coold a | little then add 1 lb of Varnish boild and stird, coold a lb of | turpentine added – – if a bright color. powderd amber | must be used in a close vessel dissolved in transparent | varnish
Moistend with Alcohol and triturated till dry for a | powder [?for C.] triturate with Copal forms a | mass or added to Oil of turpentine ½ Oz to a Quart | and the Copal reduced to a powder <[?boild]> set on | so as to boil immediately in a bottle of 2 Quarts and | stopt close
This is one of fourteen pages of notes on varnishes and colours resulting from chemical reactions between folio 62 verso (D09974) and folio 55 recto (D09959), working from the back of the sketchbook as now foliated. As discussed in the sketchbook’s Introduction,2 most are taken from William Nicholson’s 1808 Dictionary of Practical and Theoretical Chemistry, in this case from the unpaginated entry on ‘Varnish’:
Of this sort is the amber-varnish. To make this varnish, half a pound of amber is kept over a gentle fire in a covered iron pot, in the lid of which there is a small hole, till it is observed to become soft, and to be melted together into one mass. As soon as this is perceived, the vessel is taken from off the fire, and suffered to cool a little; when a pound of good painter’s varnish is added to it, and the whole suffered to boil up again over the fire, keeping it continually stirring. After this, it is again removed from the fire; and when it is become somewhat cool, a pound of oil of turpentine is to be gradually mixed with it. Should the varnish, when it is cool, happen to be yet too thick, it may be attenuated with more oil of turpentine. This varnish has always a dark-brown colour, because the amber is previously half-burned in this operation; but if it be required of a bright colour, amber-powder must be dissolved in transparent painter’s varnish, in Papin’s machine by a gentle fire.