Sympathetic Ink . 135 
the Ink called Sympathetic A Grain 
of Arfenic will alfo convert a Found of Cop- 
% As Tome of my Readers may poffibly not know the Ex-, 
periment here referred to, I fhall give it by Way of 
Note, which thofe acquainted with it may if they pleafe 
pafs over. s 
Orpiment half an Ounce, and one Ounce of Quicklime, 
being powdered feparately, then mixed together, and put 
into a Matrafi with five or fix Ounces of Water, flop the 
Veffel clofe, and digeft in a gentle Sand Heat for ten or 
twelve Hours, lhaking the Mixture often. The Liquor, 
when fettled, will be very clear. 
This being prepared, write, with a firong Solution of 
Saccharin Saturni made in common Water, on a Piece of 
clean Paper, and when it is dry nothing will be feen at 
all. Put the Paper with this invifible Writing between 
the very beginning Leaves of a Book; then with a Brufti 
or Piece of Spunge, dipt in the Liquor prepared with Or¬ 
piment, wet another' Paper,, and place it at the End of 
the fame Book, oppofite to the firil Paper. Shut the Book 
nimbly, and with your Hand ftrike on it two or three 
fmart Blows ; and if it be very thick fqueeze it in a Pxefs, 
or fit u.pon it a few Minutes: after which, on opening 
the Book, you’ll find the invifible Writing black and legible, 
by the fubtile Penetration of the Steams of the Orpiment 
through all the Leaves. 
Quench burning Cork in Spirit of Wine, and when ’tls 
finely powdered make Ink, by mixing a fufiicient Quan¬ 
tity of it in Water a little thickened with Gum. Write on. 
a Paper with the Solution of Saccharum Saturni, and when 
®cis dry and invifible, write again upon the fame Place 
with your Cork and Water, which will appear like com¬ 
mon Ink; when ’tis dry rub it over with fome Cotton 
wetted in the Preparation of Orpiment, and immediately 
the Writing that was vifible will difappear, and the in¬ 
vifible Writing will prefent itfelf very legible inftead there¬ 
of. Thefe are pretty Experiments, which I feveral times 
have tried ; but they fnould be made in the open Air, 
and with great Caution, the Fumes of the Orpiment {link¬ 
ing molt abominably, and being productive of great MiG 
-phiefs if taken into the Lungs. 
