"Leaving this place, we passed down some steps into another building, devoted to the fermenting operations, and first entered the square room, which measures 140 feet by 50 feet, and contains twenty-eight fermenting squares. It was here that we saw the beer in active, or as the brewer designated it lively, fermentation, and were treated to a sniff of carbonic acid gas, much to the amusement of our guide. Crossing this floor we found ourselves in another and much larger room, which covers an area of 6,000 square feet. The floor is laid with asphalte, and it contains 160 union casks. Descending a stair, we passed through the rooms below this and the adjoining buildings, all of which are used as racking floors and store cellars. In one of them there are twenty cleansing squares or settling backs, each of an average content of 120 barrels."
"Noted Breweries of Great Britain and Ireland vol. II", by Alfred Barnard 1889, page 19.
Next Barnard visited Younger’s newer brewery, Holyrood, which had been specifically built to brew Pale Ale.
"Here there are three mash-tuns, each capable of mashing forty quarters of grist at one time, over which are the hoppers referred to, and each vessel contains gun-metal stirring gear and draining plates, manufactured by Messrs. Stewardson & Hodgson of Edinburgh."
"Noted Breweries of Great Britain and Ireland vol. II", by Alfred Barnard 1889, page 27.
The mash tuns remained of a modest size in the new brew house. A big London brewery had much larger mash tuns. Barclay Perkins had ones capable of holding 130 quarters . Even after the introduction of the Steel’s masher, mash tuns still often had internal rakes. Rakes were useful for preventing a stuck mash and, for brewers adding extra, hotter water to their mash, a way of mixing it through the grain.
This is an interesting remark about the way wort was boiled.
"In the old brewhouse, at the back of the tuns, there are two other wort coppers of 120 barrels content. The ale wort is kept boiling, with the hops in the coppers for about two hours, and the great object of the operator now is to preserve the delicate aroma of the hops. The flavour of the ale partly depends upon a careful attention to the process at this stage, as, if kept too long boiling, the fine aroma, which now so pleasantly greeted us as we approached the coppers, being evanescent, flies off with the vapour, if not carefully watched."
"Noted Breweries of Great Britain and Ireland vol. II", by Alfred Barnard 1889, page 28.
Scottish brewers seemed very keen on retaining delicate hop aroma. Presumably another reason why their boils were so short earlier in the century.
The above is an extract from my book on Scottish beer: