Sometime in the middle of the 16th century
someone figured out that a fresh laid chicken egg has a similar density as
certain strengths of solutions. The egg will float instead of sink as it would
in plain water, indicating a specific strength or density. First mentioned in
soap making manuals to check the strength of lye (1558), it quickly surfaced
both in cooking recipes to check the strength of brine (1597), a solution of
salt & water, and brewing recipes to check the strength of must (1594), a
solution of fruit or honey sugars & water.
Initially the only available references for the egg
test in brewing were from the copious but out of period 1669 cookbook The Closet of the Eminently Learned Sir
Kenelme Digby Knight Opened. Even though this manuscript came from Digby’s
lifelong collection of recipes and was posthumously published several years
after his death so could be seen as probably period, his recipes are much more
contemporary to 17th century recipes than to what is found before.
For instance, many recipes mentioned in Digby use ingredients and techniques
not yet found, or commonly used, in our period of study. The addition of
citrus, like lemons, and the use of raisins, which is common in Digby, is not
found in any of the pre 1600 recipes. And the technique of aging in the bottle,
often for a sparkling beverage, is something that does not match with the
medieval method of serving mead young or aging in wooden casks and barrels
either. But even though the recipes themselves may not be period, they do tend
to include more information on the actual process and can serve as a good
almost period explanation on previously unexplained techniques.
It was not until I delved deeper into period mead making
that I came across four late 16th century brewing recipes mentioning
the egg float test, and was finally able to firmly place this technique within
our time of study for all three crafts: soap making, cooking and brewing. This
article explores the underlying process and easy application of this intriguing
trick of science!
But doesn’t a floating egg mean the egg is spoiled? It
depends. The floating egg technique works by way of the internal design of an
egg, which includes an air sack at the rounded end of the egg for the bird
embryo to breath. A fresh egg has a relatively small air sack but as the egg shell
is slightly porous over time the size of the air sack increases as the contents
of the egg slowly evaporate and dry out. As an old egg will have a large air
sack, when put into water it will bob up and float. This test is still used in
our modern times to test to see if an egg is fit to eat before cracking it and not
be surprised with a sulfur bomb!
Because the size of the air sack changes over time,
interfering with the results of our density test, it is very important to use a
fresh egg which has not yet had time to evaporate. It is also important to
check the supposedly fresh egg as eggs sold in the supermarket are not always
as fresh as you might assume (check the sell by dates or even better, get a local
backyard egg). To do this, before every density test calibrate your egg in
plain water to make sure it sinks flat to the bottom, with both butt and tip
level. Use a wide mouth glass jar and tongs to place the egg on the bottom as
it can sink so fast it cracks in bigger jars.
The density or specific gravity of water is 1. When
minerals like salts or sugars are dissolved into water the extra particles
change the density of the solution by making it more crowded, or dense. A fresh
egg has a density between 1.03-1.1 g/ml which means it would be borne, or
float, by a solution of a density matching or exceeding 1.03-1.1 g/ml. A
saturated salt solution, or brine, has a density of about 1.2 g/ml, a wood ash
lye solution for laundry soap a density of about 1.11 g/ml and a brewing
solution would be between 1.06-1.1 g/ml – all fairly close together and why
using the egg test works, in some way or another, for all three.
In modern brewing a hydrometer is used to take a
starting (before fermentation) and finishing (after fermentation) gravity
reading. Determining the difference of sugars between start and end makes it
possible to calculate the percentage of alcohol produced by the yeast from that
difference (what is gone has been consumed by the yeast and thus converted into
alcohol). As medieval brewers were not aware of the micro-biology involved in
brewing and artificially stopping the yeast for a specific alcohol content was
not understood (how they wished to know what caused the summer ‘boiling’ and
consequent explosions of wine!), all the brewer needed to know was if there was
the right amount of sugar for proper fermentation.
Most recipes ask for so many pounds of honey to so
much water, why should you go through the trouble of checking the density to
make must? For two reasons, the first being that not all honey is created
equal. A thick syrupy honey created in a dry year will have more sugar per
liquid volume than a thin, runny honey. Both will make mead, but if you
measured a thin honey to make sweet mead you might be unpleasantly surprised at
the dry white wine-like mead you ended up with... Secondly, in period all honey
would have been used for brewing, not just the easy to extract. The centrifuge
type honey extruder is a modern convenience and allows for high yield with
minimal processing. In period honey would be extracted by hand, first by
breaking up the combs to leak out as much as they could, and then by washing
the broken up combs in warm water to dissolve the remaining and any
crystallized honey. This honey/water mixture would be of unknown strength and
would have to be checked before brewing, as not enough fermentable sugars could
result in an easily spoiled brew and too much sugar can inhibit yeast growth,
stalling fermentation and giving competitors a change. I don’t doubt master
brewers of the time could eyeball or taste and have a perfect brew each time,
but for the less initiated household brewer (and modern re-enactor) it is nice
to be able to check with a visual aide, as the Digby recipe Mr. Pierce’s Excellent White Metheglin confirms:
“When it is
blood-warm, put the honey to it, about one part, to four of water; but because
this doth not determine the proportions exactly (for some honey will make it
stronger then other) you must do that by bearing up an Egge.”
Would
any kind of fresh egg work? Not until the Digby recipe Mr. Corsellises Antwerp Meath did a recipe specify that the egg
should be a hen’s egg “as above, an Hens
Egge may swim with the point upwards”. Even so, with differences in breed,
health, age and diet the egg size & shape can differ as well. For the best
results, Digby’s Mr. Pierce’s recipe
advises to test several eggs and pick out the most average one, both in
freshness and shape.
“… and put a
good number, (ten or twelve) New-laid-eggs into it, and as round ones as may
be; For long ones will deceive you in the swiming; and stale ones, being
lighter then new, will emerge out of the Liquor, the breadth of a sixpence,
when new ones will not a groats-breadth. Therefore you take many, that you make
a medium of their several emergings; unless you be certain, that they which you
use, are immediately then laid and very round.”
But
what does “beare an egge” mean? How
does that look like? It depends on the density you’re looking for and the
solution you are playing with. For instance, in soap making two densities are
used; a strong one to make laundry soap and a weaker one to make body soap. While
in the laundry soap recipe the egg is floating horizontally at the surface
(with about the size of a quarter above the surface), as the The seconde part of the Secretes of Master
Alexis of Piemont of 1560 puts “the
Egge into it, and whiles the egge remaineth aboue”; the body soap recipe for
shampoo uses “stronge lye that will beare
an egge swimminge betwene two waters”, or, the egg is suspended in the
middle.
Soapmaking
lye looks like: laundry strength lye, and shampoo
strength lye.
This shampoo recipe is the earliest sample I've found of
the egg float density test and is part of the 1558 manuscript The secretes
of the reuerende Maister Alexis of Piemount Containyng excellent remedies
against diuers disease by Girolamo Ruscelli.
”A very exquisite soap, made of diverse
things.
Take aluminis
catini (burnt cream of tartar), quicklime one part, strong lye that will
suspend and egg in the middle, three pottels, a pot of common oil; mix all well
together, put into it the white of an egg well beaten (dispersant), and a
dishful of wheat flour (thickener), and an ounce of roman vitriol (cupric
sulfate), or red lead (lead oxide pigment) well beaten into powder, an mix
continuously for the space of three hours, then let it rest, by the space of a
day, and it will be right and perfect. Finally, take it out, and cut it in
pieces: afterwards set it to dry two days, in the wind, but not in the sun.
Always use this soap, when you want to wash your hair, for it is very
wholesome, and makes fair hair.”
(Translated by Susan Verberg)
As
the density of a saturated salt solution is fairly strong, the egg in a salt
solution would also float horizontally at the surface, similar to laundry soap
strength lye. The recipe in the 1597 cookbook The second part of the good
hus-wiues iewell by Thomas Dawson uses this technique to make sure the brine
is saturated and is the earliest mention I’ve found of the egg float test in a
cookbook. Apparently, it is also used for numerous pickling recipes of the new
world colonies but I have not found any period mentions of that as of yet.
”To keepe lard in season.
CUt your lard in faire peeces, and salt it well with
white salte, euery péece with your hand, and lay it in a close vessel then take
faire running water, and much white salt in it, to make it brine, the~ boile it
vntill it beare an Egge, then put it into your Lard and keepe it close.”
Like with soap, brewing with different sugar strengths makes for different types
of brews. The stronger the mead the longer it can keep, as Digby’s To Make Metheglin advises: “If you would have it to drink within two or
three months, let it be no stronger then to bear an Egg to the top of the
water. If you would have it keep six months, or longer, before you drink it,
let it bear up the Egg the breadth of two pence above the water. This is the
surer way to proportion your honey then by measure.” Medieval meads are
usually fermented using ale yeast, which generally dies off once the alcohol
level reaches about 10%. As an alcohol level of about 10-12% will kill off most
contaminants responsible for spoiling meads and fruit wines, a higher starting
sugar level resulting in a higher alcohol percentage would therefore allow the mead
to keep longer. Unlike the soap & brine recipes, the brewing egg does not
float horizontal but vertical, as Digby’s Mr.
Corsellises Antwerp Meath mentions “so
strong that an Egge may swim in it with the end upwards”, indicating an
intermediate strength between suspended and floating.
Both the soap making recipes and the brine recipes
indicate to boil first, then measure – the brewing recipes are not so certain
and often recommend to test the strength before boiling, as Digby’s To Make Metheglin shows: “And the time of the tryal of the strength
is, when you incorporate the honey and water together, before the boiling of
it.” apparently not realizing boiling evaporates water thereby changing the
density. The recipes can also not quite make up their mind if the must should
be cold, blood warm or boiling, which could indicate they did not understand
how temperature affects specific gravity either, as shown in the 1597 Dutch
beekeeping manual “Van de Byen” by
Theodorus Clutius; “and let it cook /
until an Egg can float in the liquid / then set it off the fire”, which could
also resulted in a nicely boiled egg if the egg is not removed... As medieval
recipes over many disciplines have a tendency to be brief to the point of missing
pertinent information, it is entirely possible the period brewer knew to remove
the egg and cool down the must, but did not bother to note that down. The 1616
Danish cookbook Koge Bog advises to “put
an egg or two into this lukewarm brew so that there is a part of egg as big as
a 2 shilling over the water then it is sweet and fat enough” which probably
is the most accurate measurement
.
Bees coming out of a hive to drive off
an intruder.
Following
are two 16th century recipes which specifically mention using the
egg float test:
Jewell House of Art and Nature by Hugh Platt, 1594.
76
A receipt for the making of an artificiall Malmesey.
Take four
gallons of conduit water, into the which put one gallon of good English honie,
stirre the honie well till it be dissolved in the water, set this water in a
copper pan upon a gentle fire, & as there ariseth any skumme take it off
with a goose wing or a Skimmer, and when it hath simpered about an hour, then
put in a new laid egge into the water, which will sinke presentlie, then
continue your first fire without any great encrease, and also your skimming so
long as any skim doth arise, and when this egge beginneth to floate aloft and
sinketh no more, then put in another new laide egge, which wil sinke likewise,
& when that second egge doth also swim aloft with the fyrst egge, let the
water continue on the fyre a Paternoster while, then take it off, and beeing
colde, put the same into some roundelet, fylling the roundelet brimful. And in
the middest of this roudelet hand a bagge, wherein first put some reasonable
weight or peize, and to everie eight gallons of liquor two nutmegges groselie
beaten, twentie Cloves, a rase or two of Ginger, and a sticke of Cynamon of a
fynger length. Set your roundelet in the sunne, in some hot Leades or other
place, where the sunne shineth continuallie for three whole monethes, covering
the bung-hole from the raine, and now and then fylling it uppe with more of the
same composition as it wasteth. This I learned of an English traveyler, who
advised me to make the same alwaies about the middest of Maie, that it might
have 3. hot moneths togither to work it to his ful perfection. […]
“Van de Byen” (Of the Bees) by Theodorus
Clutius, 1597
To
make mead.
One shall
take the rest that stayed in the basket / from the dripping of the raw honey or
zeem / and wash it with hot water / so that all the sweetness goes into the
water / until you have a tub full or two / or as much as you want: Then put this liquid in the kettle / and let
it cook / until an Egg can float in the liquid / then set it off the fire / and
pour it into the barrels and let it cool / add some yeast of beer / and set it
to rise and work / and althus filling the barrel / so the filthiness may overflow
/ and when it does not bubble or work / so shall one close up the barrel / and
let it rest. This is the way to make mead / some put in a piece of tied cloth
some cinnamon / ginger / nutmeg / cloves and similar spices / to give the mead
a good taste and scent. (Translated by Susan Verberg)
Between the end of the 16th century and the
publishing of Digby’s cookbook a number of mead recipes are found to use a
similar egg float technique as described in Digby, but with old-fashioned ingredients
and techniques. This is an interesting time of transition, as by the 16th
century not only could the average person read, due to cheaper & more
extensive trade unusual ingredients like spices, sugar, citrus, chemicals &
pigments became available to the common man. With the invention of the printing
press, vernacular as opposed Latin editions started to appear and by the
mid-sixteenth century secrets books were flooding off the presses. It was a great
time for exploration, both of the sea and in the mind, not in the least helped
by the success of the numerous secrets books, each claiming to expose trade
secrets never seen before, which greatly helped to spread knowledge which before
was only accessible to the educated elite. This period of transition shows in
the differences between Digby’s work and our time of interest, both in
ingredients used and in his often elaborate and detailed explanations.
Schematic of coins used, notice
the similarity between a Groat and our modern Quarter.
Numerous recipes in Digby mention the use of coins,
like penny, threepence, groat (about 20mm), sixpence & shilling (Scum, 24).
Diameter of the coin would be used as a size measurement of the bit of shell
sticking above the water surface, and averages a ratio of 3:1 to 4:1 of water
to honey dilution (Scum, 24), which are good fermenting ratios. This type of
measurement seems to become fairly universal in later times as observed in many
of the Digby recipes and later in the US Colonial soap making lye measurements
which often also specify an area the size of a coin, in this case a quarter.
Even though coins are mentioned in the barely out of period 1604 Complete Receipt Books of Ladie Elynor
Fettiplace “so strong of honie that
it will cover an egg to the breadth of two pence”, and the 1609 The Feminine Monarchie “make it to bear an egge the breath of a
groat”, the period recipes do not specify how the egg should float, only
that is should.
So
after all this, where do you start? With a fresh egg no more than two days old,
of the roundest kind, weighing less than or about 2 ounces. Making a brine
solution is easiest: add enough salt until it stops dissolving, which means a
saturated solution is reached, place the egg, and slowly add water until it
floats just as the recipe likes it. To test lye for soap making the egg would
be used after the heated evaporated lye is cooled down, which allows for
contaminant minerals to settle out of solution and thus not interfere with the
remaining solution’s density (for more information on leaching lye and making
soft soap see the Bibliography). For brewing, make your honey must first, heat and
evaporate as needed, let cool down to blood temperature, and add an egg. If the
egg sinks the must is too weak, if it floats close to tipping or tips, the must
is too strong. As the 1609 beekeeping manual The Feminine Monarchie instructs: “If the liquor be not strong enough to beare an egge the breath of a
two-pēce above it, thē put so much of your course hony into it, as wil give it
that strength: or rather, when it is so strong powre in more water (stirring it
with the liquor) until the egge sinke.” In other words; if it is too weak,
add more honey, stir well to make sure the sugars are completely dissolved, and
try again. If too strong, add some water, stir well, and try again. As you can imagine,
it is easier to start with too strong a solution and dilute it, than to start
with a weak solution and try to incrementally dissolve more sugars into it.
The
table below matches egg position with specific gravity, giving us an idea of
what to aim for. Egg readings are given for both 10% tolerance yeast (ale
yeast) and 12% tolerance yeast. (from The
Egg Test)
mead
|
start SG
|
egg
|
start SG
|
egg
|
style
|
10% yeast
|
reading
|
12% yeast
|
reading
|
dry mead
|
1.085
|
touches
|
1.1
|
20mm
|
Medium
|
1.095
|
18mm
|
1.11
|
26mm
|
Sweet
|
1.1
|
20mm
|
1.12
|
30mm
|
Dessert
|
1.1 +
|
> 20mm
|
1.2 +
|
30mm +
|
To
make sure there is enough sugar for the yeast to feed on, the egg should float.
But if it starts to tip over and not reliably float point up anymore, the
solution has become too strong with too much honey sugar for the yeast to
properly work and fermentation will likely stall. The average range of 1.08 to
1.12 g/ml at which the average, round fresh laid egg floats point up is also
the ideal range of sugar content for starting a successful mead. And now that you
have everything you need to make a successful solution using medieval
techniques, whether it be for soapmaking, cooking or brewing, and are able to properly
document it, let the experiments begin!
I
would like to express my thanks to Mistress Roheisa le Sarjent from Lochac for
her article The Egg Test for Period
Brewers and Mead Makers. It proved a great starting point as we’re working
from similar sources, and I’m grateful to find the heavy lifting of figuring
out egg readings already done. Tak!
“Dryckeslag, Nordisk familjebok” from
Historia de gentibus septentrionalibus or
History of the Northern People, by Olaus
Magnus, printed in Rome
1555.
Published by the Aethelmearc Gazette January 8th, 2017
https://aethelmearcgazette.com/2017/01/08/a-fresh-laid-egge/
REFERENCES
Anonymous, Koge Bog: Indeholdendis et hundrede
fornødene stycker etc. Kiøbenhaffn (Copenhagen):
Aff Salomone Sartorio, 1616. http://www.forest.gen.nz/Medieval/articles/cooking/1616.html
Butler, Charles. The Feminine Monarchie. Oxford: 1609.
https://books.google.com/books?id=f5tbAAAAMAAJ&dq=the+feminine+monarchie+butler&source=gbs_navlinks_s
(1623). Transcription by Susan Verberg.
Clutium, Theodorum Van de Byen. Leyden:
Jan Claesz van Dorp, Inde Vergulde Son, 1597.
https://books.google.com/books?id=Y0NnAAAAcAAJ&dq=van+de+byen&source=gbs_navlinks_s
Transcription by Susan
Verberg.
Digby, Kenelme. The Closet of the Eminently Learned Sir
Kenelme Digby Knight Opened, 1669
The Project Gutenberg EBook
of The Closet of Sir Kenelm Digby Knight
Opened. Anne MacDonell (ed.), 2005 https://www.gutenberg.org/ebooks/16441
Dawson, Thomas. The second part of the good hus-wiues iewell,
London: E.
Allde for Edward, 1597.
http://www.eebo.chadwyck.com
Density values from http://homesteadlaboratory.blogspot.com/2014/02/historical-lye-making-part-2.html
Krupp, Christina M. &
Gillen, Bill. Making Medieval Mead, or
Mead Before Digby. The Compleat Anachronist #120. Milpitas: SCA Inc, 2003. (includes the Complete Receipt Books of Ladie Elynor
Fettiplace, 1604).
Platt, Hugh. Jewell House of Art and Nature. 1594.
London: Peter Short. http://eebo.chadwyck.com/ Transcription
by Susan Verberg
Ruscelli, Girolamo. The secretes of
the reuerende Maister Alexis of Piemount. London: John Kingstone, 1558.
http://www.eebo.chadwyck.com.
Ruscelli, Girolamo. The seconde part
of the Secretes of Master Alexis of Piemont. London: John Kyndon, 1560.
http://www.eebo.chadwyck.com.
SCUM,
To Bear An Egge, Making mead with
medieval hydrometers, by Lord Corwin of Darkwater. SCUM 16, p.21-28.
Sibly, Belinda. The Egg Test
for Period Brewers and Mead Makers, 2004
Mistress Roheisa le Sarjent,
Cockatrice, May AS 49, p.20-29.
http://brewers.lochac.sca.org/files/2014/02/The-Egg-test-for-Period-Brewers2.pdf
More information on leaching
soapmaking lye:
https://www.academia.edu/27755101/Of_Potash_and_Lye
More information on making
medieval soft soap:
https://www.academia.edu/27757652/To_Make_Black_Sope
More information on brewing
with honey: Of Hony, a Collection of
Medieval Brewing Recipes.
WEBSITE
forthcoming…
To find a groat, and other
period coins: http://alphaofficium.weebly.com/apps/search?q=groat
Image of fresh egg test from http://media.finedictionary.com/pictures/243/38/9971.jpg
Photographs of soap making
lye by Susan Verberg, 2016.
Bees coming out of a hive to
drive off an intruder.
Museum Meermanno, MMW, 10 B 25, Folio 37r - http://bestiary.ca/beasts/beastgallery260.htm#
“Dryckeslag,
Nordisk familjebok” from Historia de
gentibus septentrionalibus, by Olaus Magnus, Rome, 1555.
https://commons.wikimedia.org/wiki/Category:Historia_de_gentibus_septentrionalibus
