CHEMICAL SCIENCE. 331 



commerce of our country, particularly in relation to its produce of sugar. I 

 have therefore deemed it a subject worthy of chemical observation and ex- 

 periments, to determine its claims as a sugar producer; and have also 

 chosen it to illustrate a uniformity of vegetable secretion, according with 

 well-known natural l.iws. In order to give scientific precision to the remarks 

 which follow, it is nerrssary that a brief definition of the term sugar, should 

 be given. So rapidly has chemical science progressed of late, that this well- 

 known term lias now heroine a generic name fur a class of bodies, individu- 

 ally presenting us with the most marked diversities of sensible characters 

 and composition. We have sugars which are sweet, others which are 

 slightly sweet, and some destitute of sweetness ; some are fermentable, 

 others do not undergo this change ; some are fluid, more are solid. 



In connection with the present subject, adopting cane sugar as the most 

 important kind commercially, and as an article of food from certain inherent 

 qualities, if we examine into its sources, we find them abundant, but not 

 numerous. So far as observation has extended, its production by a plant is 

 definite ; a change of locality, even when accompanied by a marked change 

 in the habit of the plant, does not alter essentially the nature of the sugar it 

 produces. Thus the cane of Louisiana rarely matures and is an annual, 

 while in the soil and climate of Cuba, it enjoys a life of thirty, or even sixty 

 years. The juice of our southern plant always contains more soluble alka- 

 line and earthy salts than is found in the cane of Cuba, but its sugar is 

 secreted as cane sugar. The juice of the sugar beet, of water-melons, and 

 a large number of tropical fruits, the sap of the maple and date palm, afford 

 cane sugar. In these juices and saps, when concentrated by desiccation in 

 the cells of the plants, it always appears in regular, brilliant crystals, of a 

 prismatic form, clear and colorless ; distinctly indicating a vital force in the 

 plant, separating it from other proximate principles and leaving it in its as- 

 signed place pure. 



The class of sugars next in importance, includes under the general term 

 Glucose, a number of sugars having varied characters, which should be 

 separately grouped. Among them are the sugars of fruits, seeds, and 

 grasses ; those produced in the animal system, and the artificial sugars made 

 from starch, grains, and sawdust. The varieties of glucose are both solid 

 semi-fluid. When so! id they present aggregates of sub-crystalline form, in 

 which the organic tendency to rounded surfaces, is generally seen. The 

 semifluid forms often manifest a disposition to become solid on exposure to 

 air, and they then experience a molecular change, which produces crystals 

 having new relations to polarized light and different physical and chemical 

 characters. 



It is unnecessary to enter more minutely at this time, into a description 

 of each variety of glucose, for the individuals of the class are easily distin- 

 guished from each other, and most clearly and remarkably from cane sugar. 

 The plants producing the natural glucose sugars, mature their cells as per- 

 fectly as those producing cane sugar, and the secretion can be found as dis- 

 tinctly isolated from other principles as cane sugar is, even when the glucose 

 is semifluid. Hence we are able to determine by microscopical observations, 



