By the 1890's brewers had learnt a lot not just about the suitability of specific waters for different types of beers but also how to create them themselves.
"IT is, as you know, quite possible for a state of equilibrium to exist among different salts in solution, which is readily upset by heat concentration, or even by agitation; and, as all water used for actual brewing is either previously boiled, or heated, a rearrangement may take place among the bases and acids, and a new and more stable state of equilibrium be established. We may, for instance, mix together dilule solutions of sodium carbonate or bicarbonate and calcium sulphate, obtaining an immediate precipitate, but heating immediately throws calcium carbonate-out of solution. I think it advisable, therefore, when stating the salts of a water, to consider the changes likely to be brought about on boiling, and to consider any bodies thrown out of solution as representing those originally present. This precipitation occurs when bicarbonates of calcium and magnesium are present, since they are decomposed by heat, the carbon dioxide being expelled, and the carbonates deposited. In stating the calcium and magnesium sulphates and carbonates, the two chief methods prevailing are these :—It was typical for brewers to boil their mashing water and the let it cool down to strike heat. I can't really comment on the rest of it, as the chemistry goes way over my head. Sorry about that.
(a) To estimate the combined carbon-dioxide directly by titrating the water with standard acid. This is then combined with the lime, and expressed as calcium carbonate, any excess of carbon-dioxide being combined with magnesia, or any excess of lime is combined with the sulphuric acid to form calcium sulphate.
(b) To calculate the sulphuric acid first as calcium sulphate, any excess of S03 being combined with the magnesia, or any excess of lime calculated as carbonate. The result of this second plan is that magnesium carbonate and calcium sulphate are often given as existing together in the same water (see Example 2). Now this might be the case in the' cold, but on heating with a solution, carbonate will certainly be precipitated, either of calcium, magnesium, or of both, and sulphates of one or of both will remain in solution. . To decide this question I have recently done a number of experiments, the results of which may be thus briefly summarised :--(1) When calcium sulphate and magnesium carbonate (as bicarbonate) are present in solution in equivalent amounts, double decomposition occurs, according to the equation CaSO4 + MgCO3 = CaCOa X MgSO4. The decomposition is about four-fifths complete, the precipitate produced consisting almost entirely of calcium carbonate, whilst about four-fifths of the magnesia remains in solution as magnesium sulphate. A trace of calcium sulphate is carried down with the precipitate, whilst the undecomposed one-fifth of magnesium carbonate is partly precipitated, but the greater part remains in solution. (2) When we have either calcium sulphate or magnesium carbonate in large excess, complete, or almost complete, decomposition occurs. I have not determined the exact ratio requisite for complete decomposition, since this is a point of mainly theoretical interest."
The Brewers' Guardian 1893, page 109.
"Evidently, then, in combining the lime, magnesia, carbonic and sulphuric acids, the order to be adopted is-
SO3 combined first with magnesia, and then lime.The importance of this is seen in the following examples, where the first column of each series gives the salts calculated on this basis and the second column on the old basis. Leaving out the soda salts we have—
CO2 combined first with lime and then magnesia.
A B C 1 2 1 2 a b a b a b a b Magnesium sulphate 6.27 - 30.45 - 5.16 - 7.06 - Magnesium carbonate - 4.39 - 21.31 - 1.03 4.72 9.66 Calcium sulphate 26.66 33.76 43.35 77.87 2.89 8.74 - 8.02 Calcium carbonate 7.85 2.64 33.09 7.62 25.62 21.34 24.03 18.00
You will therefore see the importance of the method employed for combining the bases and acids as salts, for thereon depends the treatment considered necessary. If, in the first water in the Table above, it were necessary to increase the calcium sulphate up to forty grains per gallon, the calculation by the first method would require the addition of 13.4 grains, whilst the second requires only 6.2 grains. Again, in the second water the two methods of calculation represent a difference of no less than 34.5 grains of calcium sulphate.
It will be found that, as a rule, all the chlorine in a water exists as sodium chloride, with sometimes potassium chloride in addition. Some waters, especially those near the coast, contain more chlorine than the equivalent of the alkalis, and in these cases either calcium or magnesium chloride is present. Now, I have frequently seen cases in which calcium chloride and magnesium carbonate are given as existing in the same water, but just as the latter salt is decomposed on heating with calcium sulphate, so also does decomposition occur when magnesium carbonate is heated in the same solution with calcium chloride, the precipitate thrown out of solution consisting almost entirely of calcium carbonate. Consequently any excess of chlorine not expressed as sodium or potassium chloride should be combined with magnesium in preference to lime. I had fully intended bringing before you some experiments on this point, but unfortunately the time required to complete them has not been forthcoming."
The Brewers' Guardian 1893, page 109.
In the 1870's and 1880's, some London brewers did indeed set up breweries in Burton to specifically brew Pale Ale. Truman and Mann are two examples. But there were also breweries who always brewed their PAle Ales in London, Whitbread and Barclay Perkins, for example.
Barclay Perkins had quite complicated water treatments, different for each style. Mild, Bitter, Burton and Porter all had different treatments. As the y included the detaails in teh front of their brewing records, I've full details. Which I'll be posting presently.