Prague Powder is a commercially-sold salt mixture used in preserving meat. It is a generic term, not a trademarked name.
The mixture is sold dyed pink to avoid confusion in homes with table salt.
The mixture contains nitrites to give meat its pink colour, and prevent botulism. The nitrites break down into nitric oxide and then dissipate. Ultimately, what is produced in the meat is nitric oxide, which combines with myoglobin protein to give a pleasing red or pink colour to the meat. As appealing as that benefit is, it's a minor one compared to the prevention of botulism.
Two versions are sold of Prague Powder are sold; you cannot swap one for the other.
Prague powder #1 (aka Cure #1)Prague powder #1 is 1 part (6.25%) sodium nitrite to 15 parts (93.75%) salt, plus anti-caking elements.
It is used for all curing other than dry.
You use 1 teaspoon for 5 pounds (2 kg) of meat, or 100g per 100 pounds (45 kg), and mix it with cold water to use.
Prague powder #2 (Cure #2)Per pound (16 oz) (450g) of Prague powder #2, there is 1 oz (6.25%) sodium nitrite, .64 oz (4%) sodium nitrate, 14.36 oz (89.75 %) salt, and anti-caking elements.
It is mostly for dry curing (e.g. products that require no cooking, refrigeration or smoking.) These meat products typically take a longer time to cure.
You mix with cold water to use, using 1 teaspoon for 5 pounds (2 kg) of meat, or 100g per 100 pounds (45 kg.)
Certain strains of micrococcus bacteria ferment the nitrate in Prague Powder #2, converting it to nitrite.
Prague Powder #2 lasts longer in food, because while the nitrite turns into nitric oxide and dissipates, the nitrate instead has to first break down into nitrites before it can dissipate as nitric oxide, thus you have a preservative present for longer.
One of Griffiths' employees, Lloyd Augustus Hall, helped "cure" the powder's tendency to cake by introducing anti-caking agents.
Previous to Prague Powder, Griffith had been importing (since 1925) a product from Germany called "Prague Salt."
The patent of course has long since expired, which is why Prague Powder is now sold by many different makers.