176 SCIENTIFIC AMUSEMENTS. 



Expt. 191. Alcohol from Starch. During the "malting" of 

 grain, and in general during the sprouting of most kinds of seeds, 

 the life action of the growing vegetable brings about a change of 

 the insoluble starch stored up in the grain or seed into soluble 

 sugar which is contained in the sap. This chemical transforma- 

 tion can be imitated artificially, and by fermenting the sugar thus 

 produced alcohol can be readily formed from starch. In this way 

 rice starch, potato starch, and many other starchy materials are 

 employed for producing spirituous liquors, in most cases of far 

 inferior quality, viewed as beverages, than those produced from 

 natural sugar, more especially that of the grape. 



Grind up some starch with water to a thin cream, pour this into 

 boiling water, add a few drops of sulphuric acid (previously diluted 

 with water) to the fluid, and boil the liquor for some hours, adding 

 water from time to time to replace that lost by evaporation. 

 Finally add some chalk, whereby a more or less marked efferves- 

 cence will be produced, carbon dioxide being evolved, and sulphate 

 of calcium formed ; the sulphuric acid will thus be neutralised 

 (compare Expt. 165), and as the sulphate of calcium formed is not 

 very soluble in water, most of it will be precipitated as a solid. 

 Strain off the liquor and filter it ; the presence of grape sugar in 

 the clear solution may be readily shown by the copper test des- 

 cribed in Expt. 123; if the solution be evaporated on the water 

 bath (Expt. 89), a sweet solid or semi-solid residue will be left, 

 consisting of impure grape sugar. If there is enough of it, this 

 may be dissolved in water and fermented with yeast, and the 

 production of carbon dioxide and alcohol ascertained as in the last 

 experiment. 



Large quantities of converted starch are thus prepared and sent 

 into the market under various names, being chiefly used as sources 

 of alcohol in the production of fermented liquors of various kinds. 

 Some of the purer sorts of sugar thus produced are nearly white 

 and solid, and are often termed glucose ; others contain so much 

 uncrystallisable sugar that they can only be obtained as semisolid 

 soft masses, or a thick syrupy fluid. The coarser kinds are largely 

 used, under the name of malt substitutes, in brewing various kinds 

 of beers, being far cheaper than genuine malt ; but the advantage 

 to the consumer of the use of such materials is at best doubtful, 

 whilst in many instances the beer thus made is distinctly of inferior 

 quality, and sometimes decidedly objectionable ; the better kinds 

 of starch sugar are used in the preparation of wines (mixed with 

 grape juice of inferior richness as regards sugar, so as to enable 

 the mixture to produce a wine of sufficient alcoholic strength), 

 and for many other purposes, the light-coloured uncrystafiised 



