It's fascinating stuff, if only because it's so different to the supposed Scottish way of fermenting. See what you think:
Procure a gallon of brewers' best strong-ale yeast; and for this brewing you will need three fermenting tuns. It will be best to have two of them capable of containing about 42 gallons each, which will serve the purpose of fermenting a barrel (36 gallons) should it ever be found necessary. A tun capable of containing a half-hogshead will serve for the table-beer, and will afterwards ferment a kilderkin (18 gallons) if needful. As soon as your strong-ale wort is cooled to 85°, take out about a gallon of it, and pour into it three English pints, or
34 pounds3.5 pounds of the yeast. When it begins to ferment, add a little more wort, and a vigorous fermentation will soon take place. If the weather is cool, or the atmosphere from 40° to 45°, commence fermentation as soon as the wort is cooled to 75°. Pour the yeast-mixture all over the inside of the fermenting tun, as far up as the wort will rise. Turn in the strong-ale wort now, and incorporate it well with the yeast; after which cover up the tun. Follow exactly the same plan with the middle-ale wort, fermenting as before with 3 English pints of the yeast. Ferment the 16 gallons of table-beer wort at the temperature of 80° with one English pint of the yeast. You have one English pint of the yeast remaining, in case the fermentation in any of the tuns becomes languid.
On the morning after the worts have been put into the tuns, if the fermentation has gone on smoothly, the ale-worts should show a slight white cream. Break this down into the mass, stir well up the contents of the tuns, and take out a little for examination. The saccharometer should show a decrease of gravity, and the thermometer a small increase of heat. Examine the tuns again in the evening, and should the fermentation appear rather languid, add a small portion of yeast, and mix it up well with the mass. On the second morning, if fermentation is going on well, a white frothy head, something like a cauliflower, should appear on the contents of the tuns, with perhaps patches of dark-brown yeast on its surface. Be careful to remove these patches, or they will impart a harsh disagreeable flavour to the ale. Take out some of the liquor and examine it. If the saccharometer does not indicate a considerable decrease of gravity, and the thermometer an increase of heat, break down the head once more into the mass, and stir the whole well up. After this the head must remain unbroken till it is skimmed off, but samples may be occasionally taken out to ascertain to what extent attenuation has taken place. When the head assumes a dark-brown appearance, and begins to be depressed in the centre, it must be removed, or it will fall to the bottom and destroy the flavour of the ale. Be especially careful to prevent this. After skimming apply the saccharometer. Should the gravity not be reduced two-fifths,—that is, that which originally stood at 100 be reduced to 60,—and that which was 65 be reduced to 39,—rouse it well up, and skim every two hours, till this degree of attenuation is, if possible, attained. The table-beer should be put into the cask 24 hours after fermentation has commenced in the fermenting tun.
See that the casks are perfectly clean and dry. Place them on a gawntree with the bunghole a little inclined to one side, that the yeast may discharge itself freely from the ale. Fill the casks, and as for some time a considerable discharge will take place from the bunghole, be careful to supply the deficiency every two hours from the pitchers containing the over-contents of the casks. If this be not attended to the yeast will fall to the bottom, and make the ale harsh, besides rendering it liable to new fermentation on every change of weather.
When the fermentation has subsided the casks should be firmly bunged down with wooden bungs, called by the brewers shives, and a spile-hole made in them, into which a vent-peg is put loosely for a day or two, and then firmly fixed. When ale is made in March and intended to be kept over the summer, it may be advisable to put 4 or 6 ounces of the finest hops into every half-hogshead ; or the half of this quantity if the ale is racked off into quarter-hogsheads or kilderkins, which are perhaps more convenient for domestic use.
If notwithstanding all your care the ale should be cloudy, it will be necessary to fine it by artificial means. To do this yon must dissolve an ounce of isinglass in a quart of cider or stale beer, allowing it to stand for several days, when another quart of cider or beer may be added. Strain this through a sieve, and put nearly the half of an English pint of it to each quarter-hogshead or kilderkin, mixing it thoroughly with the ale. Ale should not be fined in this manner unless absolutely necessary ; for is has a strong tendency to flatten it and promote acidity.
In this brewing the strong-ale wort may have a gravity of from 112 to 115; the middle-ale wort, a gravity of 74; and the table beer wort, a gravity of from 48 to 50."
"The cook and housewife's manual" by Margaret Dods, 1847, pages 648 - 650.
It begins normally enough, with making a yeast starter. Nothing odd about that. But look at that pitching temperature: 75º F. Admittedly, it does say this is when the ambient temperature is cool. Even so, it seems very high. Though not as bad as for the Table Beer, which is pitched at 80º F. Oddly enough, there's no mention of the pitching heat in warm weather. Presumably that was lower.
The temperatures quoted are totally at odds with what Roberts suggests in "Scottish Ale Brewer": around 50º F. And not much like what William Younger did, either. They pitched their 120/- Ale at 55º F and their Table Beer at 58º C.
It seems that the practice of mixing yeast with a small amount of incompletely-cooled wort used to be employed by commercial brewers:
"The mode which the Scottish brewers adopt in pitching their tuns is very similar to that in England; though, generally speaking, they do not now, as formerly, let down a small portion of the worts into the gyle-tun at a higher temperature, along with some of the store. That former practice, which appears to me very judicious, as it gives the brewer some idea of the strength of the store before he mingles it with the whole of his worts, is still employed by a few."
"The Scottish ale-brewer and practical maltster" by William Henry Roberts, 1847, pages 114 - 115.
Note the beating down of the yeast at the start of fermentation. Commercial brewers did that, too. Except they continued doing so most of the way through the fermentation.
A demonstration of how commercial and domestic brewing was diverging as the professionals changed their equipment and techniques to reduce the amount of labour required.
That's a fair amount of dry hops being added. Remember that they're using a half-hogshead and not a barrel. The rate is 5.33 to 8 oz. per 36-gallon barrel. Rather later - 1868 - William Younger added about 4 oz of dry hops per barrel to their 120/- Ale.
Old brewing instructions often mention that beer should clear itself spontaneously, if stored and matured correctly. The alternative, then as now, was to fine with isinglass. I'm not surprised finings tended to make beer go sour if they used stale beer or cider to dissolve the isinglass with. Sounds like asking for an infection.
And there we have it. Full instructions on how to brew at home in mid-19th-century Scotland. Very handy.