In finding out the meaning of a cryptograph, you must first settle in your mind to what class of cipher it belongs, whether it is written by means of letters, figures, or signs; having done so, you must go to work with patience, and try to find out, by means of perseverance and study, what each figure, sign, or letter represents; as even the above specimens of cryptography can be so altered and improved upon, yet continuing in their original form to some extent, that it would be impossible to give positive rules to enable any one to decipher any kind of cryptograph; in fact, it can only be done by those who have made it their study for years, and consequently have had great experience in the matter.
Most of the examples given will only enable one to decipher the most simple kinds, such as are generally found in magazines, &c.; for if that intricate cipher of Lord Bacon’s were put in a book for boys, it would be a waste of paper, as we will venture to say that not one in a thousand would be able to find it out.
There is another class of cryptographs which we have not yet noticed, and which are done by means of sympathetic inks, a list of which will consequently be interesting.
Inks which appear when heated, and become invisible when cooled:—
Solution of nitro-muriate of cobalt; when heated turns green.
Solution of acetate of cobalt, with a little nitre; rose-colour when warm.
Inks which remain visible when heated, but do not disappear when cooled:—
Onion-juice, yellow; equal parts of copper and sal-ammoniac in water, yellow; aquafortis, spirits of salt, oil of vitriol, and salt and water, yellow or brown.
Inks which appear when exposed to light:—
Diluted solution of nitrate of silver.
Diluted solution of terchloride of gold.
