Here's an unusual one from my collection. It's written in Bolak
, a.k.a. the Blue Language, an artificial international language published by Léon Bollack in 1899.
Havana, Cuba, [23 or 25?] April 1901.
Very dear Madam,
I have seen your name in a list of scholars of B[olak], and I note that you persevere in this language.
Please tell me how it progresses in your country. May I request permission of you to correspond with me in B[olak] for practice? If it is not inconvenient for you, send me some postage stamps of the last issue of your country, and I shall do likewise in return-post to you.
Put my name in a list of your friends,
JOSE M. ROVIRA
Zulueta 32 A. -- Havana, Cuba
Regarding the uncertainty of the date, Señor Rovira wrote "dovistel", which is nonsensical; he must have meant either "dovister" (23) or "doviskel" (25). In the closing, he wrote "serf" (proletarian), but presumably meant to write "sarf" (servant).