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KF5JRV > TECH 02.08.16 12:45l 123 Lines 6010 Bytes #999 (0) @ WW
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Subj: How to Make a Fitzroy Storm-Glass
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Sent: 160802/1131Z 7027@KF5JRV.#NWAR.AR.USA.NA BPQK1.4.65
How to Make a Storm-glass
The storm-glass consists of a mixture of chemicals sealed in a hermetically
sealed glass bottle. The proportion of the various chemicals is quite critical
and may need to be adjusted to suit your local climate (more on that later).
Also, the operation of the instrument seems to be affected by the size of the
jar; for a given mixture, a storm-glass made using a small phial will react
quite differently to one made using a pickling jar. When mixing the chemicals
it is necessary to warm the mixture slightly so that they all dissolve. This
can be done by placing the ingredients in a sealed glass container and
immersing it in warm water and then vigorously shaken.
Some Recipes
Here is a description of a practical storm-glass taken from the book
Pharmaceutical Formulas by Peter MacEwan, published in 1908. The article
includes notes to assist in the reading of the instrument.
Chemical Barometer Recipe 1 from Pharmaceutical Formulas
Camphor - half ounce
Ammonium chloride - half ounce
Potassium nitrate - half ounce
Rectified spirit - one ounce
Distilled water - two ounces
Weigh the spirit into the bottle and dissolve the camphor, then add the
salts and the water (warm). Shake, and when dissolved filter.
Long narrow tubes of glass are filled with this solution and hermetically
sealed or corked. The tubes are then affixed to boards by means of wires
in the same way as barometers are fixed. The changes of the solution
signify the following:
Clear liquid : Bright weather.
Crystals at bottom : Thick air, frost in winter.
Dim liquid with small stars : Thunderstorms.
Large flakes : Heavy air, overcast sky, snow in winter.
Threads in upper portion of liquid : Windy weather.
Small dots : Damp weather, fog.
Rising flakes which remain high : Wind in the upper air regions.
Small stars : In winter on bright, sunny days, snow in one or two days.
The higher the crystals rise in the glass tube in winter the colder it will
be.
Interestingly, in a supplementary chapter to this book, another storm-glass
recipe was given including a more descriptive set of notes to aid in the
prediction of the weather:
Chemical Barometer Recipe 2 from Pharmaceutical Formulas
Nearly fill a glass tube 10 in. long and ¾ in. diameter with the following
liquid, then hermetically seal:-
Camphor - 2 drachm
Potassium nitrate - ½ drachm
Ammonium chloride - ½ drachm
Absolute alcohol - 2 ounces
Water - 2 ounces
Disolve.
Temperature is the main factor in changing the appearance of the solution.
The indications are as follows:-
(a) During cold weather beautiful fernlike or feathery crystallisation is
developed at the top, and sometimes throughout the liquid. The
crystallisation increases with cold, and if the structure grows downwards
the cold will continue.
(b) During warm and serene weather the crystals dissolve, the upper and
greater part of the liquid, becoming perfectly clear. The greater the
proportion of clear liquid, the greater the probability of fine dry weather.
(c) When the upper portion is clear and the flakes of crystals rise to the
top and aggregate, it is a sign of increasing wind and stormy weather.
(d) In cold weather if the top of the liquid becomes thick and cloudy, it
denotes approaching rain.
(e) In warm weather if small crystals rise in the liquid, which still
maintains its clearness, rain may be expected.
(f) Sharpness in the points and features of the fern-like structure of the
crystals is a sign of fine weather ; but when they begin to break up and a
re badly defined, unsettled weather may be expected.
Note: 1 drachm = 3.89 grams.
An American book by Henry B. Scammell published in 1897 entitled Cyclopedia of
Valuable Receipts gives an interesting variation of the description of the
Stormglass. Here the action of the instrument is attributed to, at least to
some degree by variations in atmospheric pressure. Notable is the lack of
water in this recipe as proof spirit is in fact a mixture of alcohol and
water (50% by volume in the US).
STORM-GLASS - A thin glass tube, about 12 inches long and 3/4 inch in
diameter, about 3/4 filled with the following liquid, and covered with a
brass ear, having an almost capillary hole through it, or else tied over
with bladder. Take of camphor, 2 dr.; nitre, 1½ dr.; sal ammoniac, 1dr.;
proof spirit, 2 ¼ fl.oz.; dissolve and place in the tube. When the liquid
is clear in all but the lower portion of the tube, it denotes clear
weather; when the cloudy appearance arrises in the middle, a change in the
weather is indicated; when the whole contents of tube become clouded with
the mixture, rainy or stormy weather is to be betokened. Thus a simple
barometer may be made for home or office use. This invention will be more
reliable in action if the glass is kept in the outer air, under shelter.
After constructing many storm-glass instruments using recipes from various old
texts, it may became apparent that they were all designed for use in regions
with a with a different climate than your location.
Consequently, the quantities of the ingredients were altered to give good
results for warmer climes. The end result is a storm-glass that gives results
very similar to those described in the old texts.
Another problem relates to the comfort of the modern home. As the storm-glass
is an instrument that reacts to environmental temperature changes, it works
best in a draughty, un-insulated and unheated home. This makes finding the
optimum mounting position of the storm-glass an interesting problem. It should
preferably be placed in the shady part of the home near a large window where
direct sunlight will not fall on the instrument.
73, Scott kf5jrv
KF5JRV @ KF5JRV.#NWAR.AR.USA.NA
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