Publisher's Synopsis
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1781 edition. Excerpt: ...of their modern colouring, to their craft, on finding us so easily satisfied. But the principal reason given by these writers, is, on account of the considerable quantity of zaffre and smalt now exported from Europe to China, which Mr. Bowles takes no notice of. Zaffre has been thought of such use in England, that the society for the encouragement of arts, manufactures and commerce, promised in 1755, a premium of 30I. for making the most and best zaffre, and smalt from English cobalr, not less than 51b. weight of zaffre, and 151b. of smalt to be produced before the society, with satisfactory certificates. About seven shillings and six-pence sterling. W without further process. LETTER Cobalt has been found in Cornwall and Scotland, and probably in other parts of Europe, of various colours and hues, mixed with different substances jwhich mineralists have fully described, particularly Cronsted. Wallerius enumerates six different species thereof. If well calcined cobalt be treated with inflammable matter, and fluxed like other metallic calxes, it will be reduced to a semi-metal, called by Mr. Brandt, of the Swedish academy, who first produced it, regulus of cobalt. This regulus, and also the calx of cobalt, amongst other singular properties, makes sympathetic ink, by being dissolved in aqua regia. This ink may be applied to the drawing of landscapes, in which the ground and trees are destitute of verdure, being first drawn with Indian ink, giving an appearance of winter; but those parts covered with this preparation, resemble the spring, on being exposed to a gentle heat, when the green leaves appear on the trees, and the grafs in the fields, which idea has been executed in France by an ingenious artist on a sire-screen; and as..."
