198 MINERAL FOODSTUFFS. 



may be taken as the average phosphoric acid content in barley, 

 though C. LINTNER (I.) reports an instance of a Hungarian 

 barley from the year 1877, which exhibited the remarkable low 

 content of 0.58 per cent, and furnished worts with such a low 

 attenuation, and sedimental yeast of such enfeebled fermentative 

 energy, as to cause great trouble ; whereas barleys of the same 

 origin, but from the preceding year, and containing 0.67 to 1.06 

 per cent, of phosphoric acid, yielded readily fermentable worts 

 under equal conditions. Given parity in the requirements of 

 phosphoric acid content by the yeast, and equal treatment in 

 brewing, a wort low in phosphoric acid will give a relatively far 

 poorer beer. As a matter of fact the corresponding percentages, 

 so far as they have been published up to the present, fluctuate 

 within wide limits, 0.026 and 0.115 P er cent/ . of P 2 O 5 in the case 

 of German beers. For this reason, as has already been shown by 

 G. HOLZNER (I.), the proposal of J. SKALWEIT (I.) and FRITZ 

 ELSNER (I.) to employ the phosphoric acid content of beer as a 

 measure of its quality or purity, falls to the ground. Lessened 

 attenuation, in consequence of a scarcity of phosphoric acid in the 

 wort, is also frequently experienced in British (top-fermentation) 

 breweries. The remedy applied in such cases is to fortify the 

 wort with phosphates, potassium phosphate in particular. Care is, 

 however, necessary not to employ an overdose, the observations of 

 A, G. SALOMON and W. DE VERE MATHEW (I.) apparently indicat- 

 ing that an excess of phosphates retards fermentation. Among 

 artificial adjuncts for such purposes, mention may be made of 

 G. FUNK and N. VON BALOGH'S (I.) patented method of employing 

 glycerophosphoric acid, C 3 H 5 (OH) 2 H 2 O, the calcium and magne- 

 sium salts of which are soluble in water. 



Considerable advantages can be derived from these observa- 

 tions in the preparation of mead or honey wine. Honey is very poor 

 in ash constituents and nitrogenous nutrition, the quantity being 

 usually too small for even moderate development and fermentative 

 activity of the contained yeast cells. The resulting difficulties, 

 well known to all mead manufacturers, can be obviated by treat- 

 ing the honey with nutrient salts. The following recipe for the 

 preparation of mead is based on researches carried out by G. 

 GASTINE (I.) : About 230 grms. of honey are dissolved in i litre 

 of water and treated with 5-7 grms. of a mixture of nutrient salts, 

 composed of diammonium phosphate 100 parts, neutral ammonium 

 tartrate 350, potassium bitartrate 600, magnesia 20, calcium 

 sulphate 50, common salt 3, and tartaric acid 250 parts. The one 

 part of sulphur, also recommended by this author, is, however, 

 preferably omitted. The solution, prepared as above, is boiled 

 up, and after recooling is pitched with wine yeast, which quickly 

 incites a powerful fermentation that runs its due course. It 

 should not be forgotten that an improvement in the flavour of 

 the mead may be expected from the employment of a selected 



