Scientific recreations in philosophy and mathematics. Including arithmetic, acoustics, electricity, magnetism, optics, pneumatics; together with amusing secrets in various branches of science: the whole calculated, to form an agreeable and improving exercise for the mind / [William Enfield].

  • William Enfield
Date:
1825
Catalogue details

Licence: Public Domain Mark

Credit: Scientific recreations in philosophy and mathematics. Including arithmetic, acoustics, electricity, magnetism, optics, pneumatics; together with amusing secrets in various branches of science: the whole calculated, to form an agreeable and improving exercise for the mind / [William Enfield]. Source: Wellcome Collection.

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    Yellow Ink. _ Take saffron and yellow berries (graine @’ Avignon, ) or gamboge, and dilute them as before, in gum water. Green Ink. This ink is made by boiling sap-green in water, in which a little rock alum has been dissolved. Ink of different Colours, made from the juice of Violets. _ Dip a camel’s-hair brush in any acid, such as diluted spirit of vitriol, and draw it over a part of the paper. When the liquor is dry, write on it with a pen dipped in violet juice, and the writing will immediately appear of a beautiful red colour. i hs If a camel’s-hair brush, dipped in an alkaline solution, such as that of salt of wormwood in water, be drawn over the other part of the paper, by writing on it when dry with juice of violets you will obtain characters of a beautiful green colour. If you write with the juice of violets, and draw a brush dipped in spirit of hartshorn, or a solution of salt of worm- wood dissolved in water, over another, you will have red and green writing, By exposing this writing to the fire, it will become yellow. f you write on paper with an acid, such as lemon-juice (which is as proper for this purpose as any other), ard then suffer it to dry, the writing will be invisible till brought near the fire, when it will become as black as ink. The juice of onions produces the same effect. . The older writing of this kind is, the more beautiful the colour becomes; and, in like manner, the longer: the spirit of vitriol], or solution of salt of wormwood, &c. has been left to dissolve, before they are used to write with, the brighter will be the colours, . Tracing Ink. This name is given to a kind of ink employed for tracing out figures, and other subjects, intended to be engraved, as by means of pressure it may be transferred from paper, and fixed on the white wax with which engravers cover their plates.