One of the more fun things to emerge in Wednesday’s dump of declassified CIA documents is a previously confidential formula for something called German secret ink. As it turns out, the recipe is easy to follow and consists of common household items like aspirin and distilled water.

The recipe is as follows.

First you have to treat the paper. It will require two baths of special formulas. The first bath consists of:

22 grams of slightly camphorated alcohol

50 grams of distilled water

50 grams of nitrate of potash

27 grams of acetic acid

20 grams of chloride of carbonide

Wait for the paper to completely dry. Then treat it to a second bath with a mixture of:

100 grams acetic acid

100 grams 90 proof alcohol

50 grams distilled water

15 grams of tinoture of capsium

50 grams of chlorhydrate of quinine

Next you make the ink, using two simple ingredients:

1 gram of compressed pyramiden

1 gram of compressed or powdered aspirin

Mix those together with 400 ounces of pure water and boom — invisible ink to write furtive love letters or even solve Sherlock-level mysteries. The power is yours to wield.

Other declassified documents include plans for the Berlin tunnel, which were used to intercept Soviet forces; reports of flying saucers; documents about the “Massacre” at the CIA which involved firing nearly 200 secret agents in 1977; and documents exploring psychic abilities.

The CREST database is worth a dive, and thankfully not written in German secret ink … for now.

Photos via Flickr / ocularinvasion