All Storm Glasses consist of Water, Camphor, Potassium Nitrate, Ammonium Chloride and Ethanol; however recipes differ a great deal. Below are listed the formulas I could find, with their historical sources noted, if possible. Note that I have given recipes in their Original unit types- which you will find is a combination of Apothecaries, Metric and Imperial weight measurements.
Negretti & Zambra (Zambretti)
- 80 grams 84% Ethanol
- 6 grams Potassium Nitrate
- 6 grams Ammonium Chloride
- 6 Grams Camphor
- 200 grams Distilled Water
From the book “Bizzare Barometers” by Phil Collins of Barometer World:
In the first bottle:
- 10 oz (283.5g) Camphor
- 20 (567g) oz Spirits of Wine (190 proof ethanol)
In a second bottle:
- 5 Drams (19.45g) Potassium Nitrate
- 5 Drams (19.45g) Ammonium Chloride
Filter and add slowly the 2nd solution to the first, constantly shaking, until the camphor is precipitated to a depth of approximately 1/3rd of the solution. Once this has done so, let the solution stand for several days, and check if the solution is indicating
Note: Drams in this case are likely Pre-1864 Apothecaries weights, and I assume 1 Dram = 3.89 grams.
From the Hong Kong Chemical Society
For each 100 ml of solution
- 40 ml Ethanol
- 33 ml Distilled Water
- 10g Camphor
- 3.8g NH4CL
- 3.8g KNO3