GRAPE-SUGAR, OR GLUCOSE. 127 



plantation, holes are dug of about two feet in depth, in which a 

 layer of sand, about six inches in depth, is put, upon which the young 

 plants, still adhering to the fruit, are placed ; the hole is then filled 

 with sand, and the surface is covered with a little earth. The young 

 trees require watering every day during about three years. The 

 palm begins to be productive at the age of seven or eight years, and 

 it continues to yield fruit, or sap for the manufacture of sugar, during 

 a very considerable period, without causing any further cost for cul- 

 tivation.* The sap of the greater number of the palms appears to 

 be rich in saccharine matter ; it is obvious, indeed, that every sap 

 that is capable of supplying a vinous liquor by fermentation, may 

 also furnish sugar; and if the palms have not generally been grown 

 with a view to this product, it is because the fruit must then be 

 given up, and, both in India and South America, the produce in the 

 shape of oil from the nuts of the palm, is almost always more valu- 

 able than that which can be had in the shape of sugar. f 



GRAPE SUGAR. 



We have already said that starch acted upon by acids, and by 

 malted barley, is changed into a saccharine fermentable substance, 

 which, both in regard to flavor and physical properties, differs in 

 many respects from the sugar which we have hitherto been engaged 

 in studying. As this substance exists naturally in the grape, it has 

 been called grape sugar, a name for which the generic term glucose 

 has been lately substituted in France, this term being used to include 

 all the sugars that are analogous to grape sugar. Grape sugar oc- 

 curs in the form of small white and very soft crystals, grouped in 

 tubercular masses; it softens at 60^, (140° Fahr.,) and becomes 

 quite sirupy at 90°, (194° Fahr.) Alcohol free from water dissolves 

 none of it ; but diluted alcohol takes up a considerable quantity. 



In the grape this sugar is associated with cream of tartar, tartrate 

 of lime, and several other saline matters. It is easily extracted 

 from the fruit ; but the grape sugar of commerce is now universally 

 prepared from starch ; large quantities, indeed, are manufactured on 

 the continent for the preparation of spirit, and for the amelioration 

 of wine, beer, cider, &c., in short, to supply sugar wherever it is 

 defective in the natural or artificial musts that are subjected to fer- 

 mentation. In England considerable quantities are also manufac- 

 tured ; but here the law does not allow it to be used in the same ad- 

 vantageous direction as in France and Germany ; all that is made is 

 employed for mixing with adulterating cane sugar, which is an arti- 

 cle of higher price. 



The sugar that is made from starch, and that is obtained from the 

 grape are identical in composition, as is that also which is found in 

 the urine of persons laboring under diabetes. 



* Buchannn. A Journey from Madras, &c., vol. i. p. 155. 



t In British India the cocoa-nut palm is beirinning to he extensively cultivated as a 

 means of producing su^ar. A considerable portion of the East India sugar now brought 

 to market, is manufactured from the palm-tree. It is not improbable, indeed, that the 

 palm of one species or another will one day supersede the sugar-cane and the beetaa 

 th8 source of all the sugar consumed in Europe.— Eng. Ed. 



