=Substitutes for Malt= have been largely used. Thus by the action of sulphuric acid on starch, an artificial form of sugar is produced, which is largely used in place of malt for making beer. Many recent cases of poisoning by arsenic have been traced to the use of impure sulphuric acid in manufacturing this form of sugar.
The detection of arsenic in organic liquids requires great care, as so many compounds of arsenic are volatile, especially in the presence of chlorides, as in beer. To _detect arsenic in beer_ a pint of the beer is evaporated to dryness, and treated with 20 c.c. of strong sulphuric acid, heated, and 20 c.c. of strong nitric acid added drop by drop. Violent action occurs: if possible 20 c.c. more of nitric acid are worked in. Transfer the liquid to a small flask, and expel the nitric acid by boiling. By this means all chlorine is expelled, the arsenic is oxidised and the organic matter destroyed. SH₂ gas is now passed into the acid liquid for some hours, the precipitated sulphur and any sulphide filtered off and extracted with ammonia, which dissolves any sulphide of arsenic. The liquid so obtained is subjected to Marsh’s test. (See page 216.)
In the making of beer from malt, the first stage is to malt the barley, _i.e._ leave it spread on floors for ten days after soaking. This allows germination to take place, in which process the insoluble starch is converted into starch, dextrine, maltose and glucose. After the dried malt has been screened to break off the sproutings, the brewer places it in the mash-tub, with water, at a temperature of 160° F. This completes the transformation of the starch into glucose. The =wort= is now boiled to stop the process, and the albumin from the grain is thus coagulated. Hops are added at this stage. The boiled liquid is passed into shallow vessels and cooled. The proper temperature for “top” yeast is 60° F., for “bottom,” or Bavarian yeast, a much lower temperature is desirable. When the desired temperature is reached, the liquid is run into the fermenting tun along with yeast. The varieties of beer are due in part to the degree of completeness of fermentation of sugar allowed. If too complete, the beer does not keep well.