converting malt/beer ratios to original gravities: the beer historian's conundrum

One of my favorite blogs, Shut up About Barclay Perkins, is mostly about the history of beer and brewing. Ron Pattinson posts some really great stuff from primary sources (where he gets it all I have no idea) and I think this semester I might have my beer class (which I should have been preparing for instead of writing this post) read some of when we talk about the Porter Revolution. Maybe.

Today Dr. Pattinson posts some recipes from A Cyclopaedia of Six Thousand Practical Receipts, and Collateral Information by Arnold James Cooley (1854). It was common practice before the widespread acceptance of the hydrometer (or saccharometer) to express the strength of a beer in terms of how much malt was used to make it. This makes sense considering the fact that alcoholic strength depends mainly on how much sugar the yeast have to convert to alcohol and how much sugar depends on how much starch you have from the grain.

But there are other things that effect the alcoholic strength of a beer and this is what makes using malt/beer ratios problematic. The quality of the grain, how the mash is conducted (temperature for instance), the moisture content of the grain, how the fermentation is conducted (temperature for instance), what kind of yeast is used etc. all influence the strength of a beer. So the malt/beer ratios can be pretty variable indicators of beer strength.

But historians of beer and brewing have little choice but to make do with this system because it's all we have. And to get an idea of how strong these beers were it's helpful to try and convert the malt/beer ratios into original gravities, into figures that represent the density of the wort prior to fermentation. Because the density of wort is influenced primarily by the amount of sugar in the wort, it is a good indicator of how strong the beer can be. Of course you have to take into account how the fermentation it conducted etc. but original gravity is a much better indicator of the potential strength of a beer than is malt/beer ratios.

And it's the way we speak about the strength of beer today so it's something we can wrap our heads around pretty easily.

So let's get down to the brass tacks, as it were. Dr. Pattinson intimates that Cooley had no idea what he was talking about for several reasons, but the one I latched onto was the fact that he thinks Cooley got the malt/beer ratios wrong.

For the "Ale, Burton" Cooley says a barrel and a half of beer (48 gallons) was drawn from a quarter of malt (64 gallons of malt). Pattinson says this would result in an OG of over 1400. This is very, very strong. With today's technology you could probably make a 16% abv beer from that wort. In the 1850s, they probably would be able to coax that wort down to a final gravity of at most 1040, probably lower, making a beer of over 13% abv.

Similarly, in his description of "Ale, Dorchester" Cooley says they drew two barrels (64 gallons) from one quarter of malt. Pattinson claims this would give an OG of 1100. Again, this is very strong. This wort would likely make a +10% abv beer.

I think Pattinson might be overshooting a bit.

In her wonderful book Country House Brewing in England, 1500-1900 Pamela Sambrook says that October Beer (the strongest brewed in the English country house) would typically be a barrel drawn from ("well over" in some cases) one quarter of malt (more than eight and a half bushels). And I doubt this brew had an OG over 1140 and therefore a FG probably over 1050 FGs probably go higher the farther back in history you go). And by Pattinson's conversions a quarter of malt would make a barrel of beer with an OG probably over 1180, extremely strong.

Similarly, the "Ales" that were commonly brewed in these country houses were made by drawing one barrel from usually four bushels of malt, or half a quarter, or two barrels from one quarter (p.117). And this brew was meant for regular consumption (at least by the families, at least before ~1700) so I doubt it had an OG of 1100. Because regular consumption of a beer over 10% abv would make you drizunk like you wouldn't belizeve.

Moreover, entire guile small beer in both Sambrook and Ellis is about five barrels from a quarter (Sambrook p.121), which by Pattinson's calculations would probably be around 1040, too strong to adequately quench the field laborer's thirst without making him fall down wasted betwixt the rows. I'm thinking small and table beer had OGs around 1020.

Ellis gives similar numbers in The London and Country Brewer for strong ale as well.

In Bennett's Ale, Beer, and Brewsters she claims that on Lady Clare's estate in the 14th century they were brewing almost 500 gallons of ale per week, drawing two barrels from each quarter (p.18). On Pattinson's conversion, that's a shit ton of 1100 OG ale to be brewing every week. And a lot of very strong ale to drink considering Bennett says that in an average household a person would drink about 1/4 gallon of ale every day (p.19). A drunken household indeed.

I suppose I would just be interested in knowing how Pattinson does his conversion and the justification for it because it doesn't square with what I know from the primary and secondary literature on the subject. I've built this nice little house of historical beer strengths and with one wave of his hand Pattinson threaten's to blow it off like so much fart in the wind.