that is invisible, or nearly so, until it has been acted upon by the air or trea

r he could be supplied with a writing fluid that would give writing which would fade away in a short time, and also with another ink that would p

dling on the race-course. He had made tempting bets on certain horses, the names of which he h

lip of paper gradually faded away while the nam

hurried away to the police station, and was in time to let the superintendent see the nam

frequently used for this purpose is a weak solution of starch containing a slight trace of iodine, the effect of which

ng inks, and some of these, such as quinoline blue, give

air and light. Or certain dye-stuffs such as magenta, that have been treated with a bleaching reagent in just sufficient quantity

red visible by chemical reagents

sulphur," which only became visible when looked at with the "eyes of affection." This appears to have been nothing more mysterious than a

gentes, but pointed out that there was nothing magnetic in their action. The term sympathetic ink appears to have or

hich changes on heating from a nearly invisible pink to blue. This peculiarity of cobalt to f

orms ordinary ink on the addition of iron sulphate; cobalt nitrate which becomes blue

he two dried constituents of the ink, say tannin and iron sulphate, are separated by the adhesive gum upon the envelope, so that sho

cheques, so that any attempt to remove the writing from the cheque by means of c

ikingly shown in the recent Sutton libel case, in which a woma

arly part of 1909, there was an epidemic of anonymous post cards in Sutto

er woman were "not fit members" of a certain congregation. Suspicion fell upon the housekeeper of the Roman Catholic

When the Assizes came on, no evidence was offered by the prosecution and the case was dismissed. The libels still continued, however, and Mrs. Tugwell having received more libellous cards, her husband again t

hat Mrs. Tugwell herself was the author of the libellous cards and letters, and

l authorities, marked a large number of stamps with a sympathetic ink, tha

hat these marked stamps were to be supplied

Cafferata, a Roman Catholic priest, and the stamps upon th

llar-box close at hand was immediately cleared of all its letters by an official. Mrs. Tugwell then put two letters in

searched, envelopes having the same watermark as that of the envelopes containing the libellous letters were discovered. There were also found some French b