CHEMICAL HISTORY OF MALTING. 103 



ing germ by vessels ramifying through the cotyledons, the dis- 

 tribution of which, also, was shown in an enlarged drawing. 

 The chemical constitution of Starch, as a compound of carbon 

 and water, was then explained, and its difference in properties 

 from Sugar, ascribed, to a difference in the proportion and 

 mode of existence of the water, in these two substances ; the 

 artificial production of sugar from starch, by the long-con- 

 tinued action of heated water, being related in illustration. 



The history of Germination having thus been considered, 

 the process of Malting was next described and examined, 

 illustrated by specimens of raw and malted grain, and by dia- 

 grams showing the comparative composition of Barley in both 

 states; the quantities of starch and gluten being diminish- 

 ed, and those of sugar and gum increased, in .the malted 

 grain *. This subject naturally led to that of Brewing, in 

 treating of which, the nature of the fermentation, or peculiar 

 chemical change (consisting in the conversion of sugar into 

 Alcohol or pure spirit), by which Beer, Ale, Wine, and other 

 fermented liquors are formed, was explained. The process of 

 Distillation was experimentally illustrated, in showing the means 

 of obtaining, from those fermented liquors, the peculiar fluid 

 from which they all derive their invigorating, as well as, when 

 misused, their intoxicating quality ; a portion of (white) 

 Brandy being distilled from Port-wine, and its properties ex- 

 amined. In connection with this subject some particulars were 

 here stated, derived from the researches of Mr. Brande, of the 

 quantities of alcohol respectively contained in the different 

 wines and other liquors. Some account was next offered of 

 the method of procuring the various kinds of spirituous liquors, 

 as Brandy, Rum, and Geneva, as well as of the mode of obtain- 

 ing proof-spirit, and lastly pure alcohol, from them ; the sub- 

 stances employed in the various processes described being exhi- 

 bited on the lecture-table. The properties of Alcohol were then 

 described, and experimentally illustrated, and those expressed 

 by numbers, such as its specific gravity, and the specific gra- 

 vity of its vapour, shown in diagrams. Particular notice was 

 taken of its permanence in the liquid form, when exposed to 

 the lowest temperatures with which we are acquainted, it being 

 stated to be almost the only substance ordinarily liquid, which 

 has never yet been frozen by artificial means, or observed to 

 freeze in nature. Its use, accordingly, in the construction of 



* Considerable difference of opinion existing among chemists with respect 

 to the distinct existence (in Barley) of the principle called by Proust Hordcin, 

 and the Teacher never having made any experiments on the subject himself, 

 it was deemed best to omit mentioning it. Dr. Thomson regards it as 

 being merely a modification of starch. 



