By ARTHUR R. LING
From The Brewers Journal – May 1917
Even before the application of science to brewing, it had been surmised by old writers that the character of the beers brewed in a given district was largely determined by the water supply of the district. Nor was it unrecognized in comparatively early times that if waters of different origin had any influence on the beer produced from them, the probable reason had to be sought in the variable saline matters in which the respective waters contained. Among the older brewing authorities there were some who attached little or no importance to the saline matters of brewing waters , and among these I may mention Shannon, Donovan, Black, Combrune, and Hayman. On the other hand, whilst Richardson, Wigney, and Roberts were advocates for the employment of soft waters, Levesque, Ham, and, in more recent years, Tizard, gave preference to hard waters, the last named, however, under reservation. But most of the observations made even as late as 60 years ago led to conflicting, and in some cases, to inaccurate conclusions.
It would serve no useful purpose in the present short article were I to enter in its relation to brewing. It will not, however, I believe, be out of place to mention briefly one episode in connection with the subject which had the effect of establishing the chief reason of the suitability of the waters of Burton-on-Trent for brewing ales. In the early part of the nineteenth century, one David Booth employed by the Society for the Diffusion of Useful Knowledge, brought out a treatise on the “Art of Brewing,” in which some reflections were cast on the practices of Burton brewers, which introduced them, as a body, to commence legal proceedings against the publishers Messrs. Baldwin and Craddock. The case was heard before the Court of King’s Bench on May 10th, 1830, Mr. Brougham appearing for the plaintiffs. Council stated that eminent chemists had visited Burton, and analysed the waters there used, and the worts produced, and the Committee of the Society above mentioned were satisfied with the honesty of the brewers, who had thrown open their doors to the chemists.
He added: “The learned person, the author of the treatise in question, who was a practical man, being a brewer of 20 years’ standing, had been misled upon the subject, by circumstances, which may have misled anybody. He had said that he could make Burton ale, similar to that of these brewers, if he were allowed to add certain saline impregnations, chiefly gypsum. Now it so happened, though the fact was not known to the author at the time the treatise was written, that the springs at Burton ran over a rock of that substance (gypsum) which gave them a natural impregnation.”
Under these circumstances the Counsel for the Committee admitted that nothing deleterious was used in Burton breweries; and the rule for criminal information was discharged upon the condition claimed by Mr. Campbell, that the contradiction should be as extensively circulated as the libel had been.
Since this time it has been known to all brewers that the principal saline constituent of the waters of Burton-on-Trent is calcium sulphate, and it has been the general custom all over the country, in case of need, to treat waters intended for brewing pale ales with one of the forms of CaSO4, 2H2O.
Our present knowledge of the effect of different salts in a water on the production of different types of beers is now considerable, but there are still some obscure points to be cleared up.
It is generally agreed that a water intended for pale ales and stock ales should contain some 60 grains per gallon of calcium sulphate, that a water for stout should contain carbonates — the London deep-well waters contain sodium carbonate to the extent of 10 grains per gallon — whilst waters intended for mild ales should contain a certain quantity of sodium chloride.
In addition to these saline requirements for special brews, magnesium and potassium salts should be present, as they tend to stimulate the yeast. I am quite aware that both magnesium and potassium salts are present normally in malt worts, but in spite of this, when they are absent from brewing waters, I regard it as advisable to add magnesium chloride up to 5—7 grains per gallon, and potassium chloride up to 3 grains per gallon.
The hardening of water with gypsum can be carried out in two ways, namely, by passing the water through a cylinder or other arrangement containing large pieces of gypsum, or by adding the gypsum in the form of a crystalline powder to the hot liquor back. The first method is uncertain, as it depends on the rate of flow of the water over the gypsum and the size of the lumps of that mineral. True, the quantity of gypsum passing into solution can be checked by taking the specific gravity of the treated water, but this involves extra work.
By far the best method of adding gypsum is the second one, but here some precautions are necessary. If the gypsum be added as a dry powder to the hot liquor back while the liquor is in a quiescent state, it will, to a large extent, sink to the bottom of the vessel, and remain undissolved. To avoid this, the gypsum should be mixed with water into a cream, and added to the hot liquor while the water contained therein is in a state of vigorous ebullition.
Some brewers find a difficulty in raising water to boiling in the hot liquor back, and merely raise it to the required striking heat. But actual ebullition presents several advantages besides that referred to, e.g., it leads to the partial removal of calcium and magnesium carbonates when this is desired.
To remove carbonates more completely — and this is practically the only way of removing carbonates of the alkalis, e.g., sodium carbonate — the addition should be made of an equivalent quantity of calcium chloride. Now this salt is an extremely hygroscopic substance, on which account it is very difficult to handle in the solid state. It is usually employed, therefore, in the form of a strong solution. In this connection I would point out that some confusion has arisen in brewing literature as regards the specific gravity of a strong solution of calcium chloride and the quantity of salt present. Thus Sykes and the writer state that a solution of specific gravity 1380 contains 63 per cent. of the salt, and that the addition of one fluid ounce to the barrel introduces 10 grains per gallon of anhydrous calcium chloride. This statement appeared in the original edition of “Principles and Practice of Brewing”, for which the late Dr. Sykes is alone responsible. He seems to have taken it from Kremer’s results, who states that a solution of calcium chloride, having a specific gravity of 1380 at 19.5 °C. (67 °F.), contains 63 parts of calcium chloride and 100 parts of water. It is easy to calculate from this that one fluid ounce would contain 232 grains, and, consequently, one fluid ounce, when added to a barrel of water, would introduce about 6.4 grains per gallon of calcium chloride. But, according to Schiff, a solution of calcium chloride of specific gravity 1403 at 15 deg. C. contains 40 per cent. of the salt or 56 grams per 100 c.c., so that the addition of one fluid ounce of such a solution would introduce 6.8 grains per gallon of calcium chloride.
Magnesium chloride, like the corresponding calcium salt, is hygroscopic, and is, therefore, conveniently added to a water in the form of a strong solution. Here again the late Dr. Sykes went astray in his directions. He states that a saturated solution of magnesium chloride has a specific gravity of 1160, and contains 45 per cent. of the salt. Further, that the addition of one fluid ounce to the barrel introduces 7.5 grains of magnesium chloride per gallon. According to Gerlach, the strongest solution he investigated of magnesium chloride had a specific gravity, at 15 deg. C., of 1334, and contained 35 per cent. of the salt, so that one fluid ounce would contain 205 grains, and this quantity, when added to a barrel water, would introduce 5.6 grains per gallon of magnesium chloride.
Some brewers prefer to add magnesium salts to their liquor in the form of magnesium sulphate (Epsom salts), which has the advantage over the chloride of being non-hygroscopic. I prefer, however, the use of the chloride, which I believe to be advantageous in regard to flavor and fulness of the beers.