You can't imagine how much this paragraph has inspired me. Really. Why? Because it made me look more carefully at certain columns in the William Younger brewing books. And I can say for certain that by 1858 they were cleansing in squares. The Edinburgh method described was clearly on the way out.
"Brewing and distillation. With practical instructions for brewing porter and ales according to the English and Scottish methods by William Stewart" by Thomas Thomson and William Stewart, 1859, page 224.
Younger's beers were fermented for 3 to 6 days in the fermenter then spent two to four days in the square before racking into trade casks.
The bit about troughs is a reference, I think, to the ponto method of cleansing favoured by many London brewers.
"There are different modes of cleansing, as stated formerly, which may be again noticed. 1st, The Edinburgh method, by which the ale is run, finished from the gyle, into the casks which are afterwards to be sent out to customers. 2d, The brewers of the Alloa and Stirling district cleanse into butts, from which the ale is afterwards racked into casks, an English pint of fillings or prepared wort being put at the same time into each. 3d, When the ale is to be made up for exportation, it is overturned into a square or vat, capable of containing the whole brewing. In this it is allowed to remain twenty-four hours; fermentation proceeds a little, and attenuation takes place to the extent of 1 or 2 lbs. per barrel. A decoction of hops is prepared, of a strength sufficient for the intended purpose, and this, with a proportion of store, is added when the ale is racked into the casks. These additions are made to preserve it in its vinous state, calculated until its time of consumpt.I told you the text was rambling and repetitive. Eventually he explains fully the Alloa and Stirling system: cleansed in butts then racked into trade casks and primed with "fillings". If you can remember back a couple of days, fillings is partilly fermented wort.
When brewers overturn their ale into squares, and rack for home consumpt, it is rather to remedy a defect than from choice. When the fermentation has run up rather too high, it may be advisable to use a square, and, if done judiciously, the ale may be brought out in a very good condition; but, after the gyle, all future racking flattens it, and injures the quality.
The practice of the Edinburgh brewers is to bring the gyle to the highest state of perfection, and tun into casks at once, where no more fermentation takes place. Neither fillings nor isinglass, in a state of finings, are used,—it being considered, that when ale is finished in fine condition, these are not requisite.
The measure of ale in hogsheads differs considerably from the English standard. The Edinburgh hogshead contains 63 gallons, and the trade generally allow 15 per cent. discount on settling accounts. The reader will take the difference of measure, which is 9 gallons per hogshead above that of England, and the liberal money discount, into any calculation he may make, in forming an estimate of the comparative advantages of the English and Scottish methods of brewing."
"Brewing and distillation. With practical instructions for brewing porter and ales according to the English and Scottish methods by William Stewart" by Thomas Thomson and William Stewart, 1859, pages 234 - 236.
I'd love to get a look at brewing records from an Alloa brewery for this period. My guess would be that, as specialist priming sugars came on the market towards the end of the 19th century that they swapped to using those. A lot less trouble than keeping a supply of half-fermented wort on hand.
That cleansing of export beer is a funny one. First because of the "decoction of hops" added to the casks at racking. A sort of dry-hopping, but with an infusion of hops rather than whole hops. I'm going back to William Younger again. Conveniently, they say which are export beers. There's no infusion added, but instead an absolute stack of dry hops: a pound or more per barrel. Almost all their beers were dry-hopped. Even most of the Milds. But I'm forgetting. Didn't Scottish brewers barely use hops?
The second odd bit is adding "store" at racking. Store is yeast. It seems starnge to go to the trouble of cleansing a beer of its yeast and then to add more. "preserve it in its vinous state" - I've no idea what that means. Sounds good, though.
We've heard that one about Edinburgh brewers not using finings a few times. Must be true, then. Unless this article is the basis of all the other texts. I've found a virtual word-for-word copy in "The complete practical brewer" by Marcus Lafayette Byrn published a year later.
Finally those wacky Scottish hogsheads holding 63 gallons. There's a name for those: wine hogsheads. It seems an odd size. Not having any other sources that confirm the use of 63 gallon hogsheads, I wouldn't like to comment on its veracity..