Talk:Wine gallon

Troy pounds
The suggestion that the wine gallon originally represented the volume of 8 troy pounds of wine is not reasonable; I think it should be 10 pounds. A troy pound is 373.24g, so the volume of 8 troy pounds is about 372.24*8/0.985 = 3.02 litres. However, the volume of 10 troy pounds of wine works out as 3.79 litres, which is very close to what we are looking for.184.187.171.177 (talk) 05:08, 9 October 2016 (UTC)

8 or 10 Troy pounds per Wine Gallon?
231 cubic inches of wine or water (which is approximately the same density due to the less dense ethanol and denser sugars, salts and other solids in solution) is much greater than 8 Troy pounds in weight, but very close to 10 troy pounds. Some references do cite 10 pounds, but others point to 8. There's also a note made to the original guild hall standard prototype cylinder actually only measuring out to 224 cubic inches (instead of the intended 230.9) but that wouldn't change the discrepancy, though would measure out to nearly 10 troy ounces of water at maximum density. (1 gram per cubic centimeter or 252.892 grains per cubic inch, with 5760 grains per Troy pound and 7000 grains per avoirdupois pound)

224 cubic inches of water weighs 9.8347 troy pounds, while 230.9 cubic inches weighs 10.1379 troy pounds

https://www.quora.com/How-was-the-gallon-measurement-invented (cites 8 Troy pounds and 224 cubic inch volume of the guild hall prototype cylinder)

https://educalingo.com/en/dic-en/wine-gallon (cites 10 troy pounds)

http://www.ibiblio.org/units/dictG.html (cites 8 troy pounds)

However, another article suggests that 9 British Trade Pounds was used, consisting of 15 avoirdupois ounces each, or 59062.5 grains. (which corresponds to 233.548 cubic inches of water) It also cites a transition from 224 to 233 to 230.9 inches in volume being used as the definition.

It asserts the original 224 cubic inch definition was either based on the French livre in a 15 ounce form (approximately 458.9 grams rather than the 489.5 grams of the 16 ounce livre, with about 30.59 grams per ounce, 472.1 grains Troy or Avoirdupois, or exactly 576 old French grains). This does correspond to nearly exactly the weight of 224 cubic inches of water. (to within four significant figures of precision, assuming 224.0 cubic inches, and certainly within 3 significant figures)

Or, alternatively, that it was based on the volume of 8 tower pounds (5400 grains) of wheat, but this explanation is described with what appears to be greater skepticism. (though it's also noted that the latter could be an equivalent standard measure to the former) (see the below reference) https://www.sizes.com/units/gallon_english_wine.htm — Preceding unsigned comment added by Kool kitty89 (talk • contribs) 07:42, 1 February 2019 (UTC)

See also: https://en.wikipedia.org/wiki/Grain_(unit) https://en.wikipedia.org/wiki/Pound_(mass)#French_livre https://translate.google.com/translate?hl=en&sl=fr&u=https://fr.wikipedia.org/wiki/Livre_(unit%25C3%25A9_de_masse)&prev=search https://en.wikipedia.org/wiki/Units_of_measurement_in_France#Revolutionary_France_(1795–1812)

With one kilogram equal to 18,827.15 French grains (and one gram to 18.82715 French Grains), one French Grain is equal to 0.053114784 grams, and the Paris ounce (of 576 French grains) is thus 30.594115413 grams.

That makes the 16 ounce Paris livre (or Pound of Paris) is 489.50584661 grams, but the 15 ounce instance in the above article would correspond to 458.911731197 grams, and the 8 pound gallon (of 120 French ounces and 69120 French grains) is thus 3671.293849574 grams, which corresponds to an equal volume of water in cubic cm or ml, or to 224.03609637296833.

That based on the modern International inch of exactly 2.54 cm, but based on: https://en.wikipedia.org/wiki/Imperial_units#Length The imperial standard yard measures 0.914398415 m, and this figure would correspond more directly to the units in British use by the late 1500s, though the original prototypes were destroyed in the 1834 Houses of Parliament fire, and exact recreations of the originals was apparently impossible, so the figure may not be helpful in this topic for a more precise conversion). Additionally, the originally specified definition of a cubic inch containing 252.458 grains of water at 30 inch Hg pressure and 62 degrees F is significantly off from the modern 252.6025 grains per cubic inch (with 0.998859 g/mL density of water at the same temperature and pressure as the 1824 standard) and even comparing the above measure of the old (existing) standard imperial yard, that only changes it to 252.6021, or both still round to the same 6 significant figures. (and around .057% discrepancy from the 1824 definition, though differences in the standard pound prototypes aren't being taken into account)

In any case, that margin of error is not large enough to shift the previous calculations outside of 224 cubic inches. (with approximately .128 inch margin of error, it still rounds to the same 3 significant figures)

The English Trade Pound
http://home.clara.net/brianp/weights.html

"The London pound, or libra mercatoria (trade pound) was 7200 grains (i.e. 15 troy ounces)."

https://en.wikipedia.org/wiki/Troy_weight#Conversions Additionally, a London pound is also equal to 16 Tower Ounces. (16 Tower Ounces = 15 Troy Ounces = 7200 Troy Grains)

8 London pounds would thus be equal to 10 Troy pounds, both being 7200 grains and much closer to the weight of one wine gallon worth of water, but doesn't match nearly as exactly as the Paris livre example. 7200 grains of water corresponds to approximately 228 cubic inches, and even with the margins of error noted above for changes in Imperial Standard prototypes (and international unit standards) and even accounting for the density of water at 62 degrees F, rounding to 3 significant figures still gives 228 cubic inches.

However, 8 avoirdupois pounds of water is approximately 222 cubic inches (and still rounds to 222 if using the 1824 definition of 252.458 grains of water in 1 cubic inch at 62 F, 30 inches Hg), which would put the 224 cubic inch figure right in between the London Pound and avoirdupois. (but neither is as close as the French derived measurements, though the London Pound instance is closer to the later 230.9 cubic inch definition)

The suggestion of a gallon composed of 9 trade pounds (of 15 ounces each, 437 grains per ounce of the early avoirdupois system) would correspond to 58995 grains, approximately 234 cubic inches of water (using the 252.458 figure as well) which is close to the 233 cubic inch figure, but still not an exact match. Without rounding, it works out to 233.682434306 cubic inches of water by that definition, and trade and measuring convention may have led to truncation of that value rather than rounding up. (as rounding down would represent the potential for less material being supplied than specified or agreed upon, which seems likely to have been a greater problem than supplying slightly more than the exact agreement)

Again, commenting on the hypothesis stated in this article, regarding the 233 cubic inch gallon: https://www.sizes.com/units/gallon_english_wine.htm — Preceding unsigned comment added by Kool kitty89 (talk • contribs) 15:30, 1 February 2019 (UTC)