SUGAR CANE. 



five or six harvests by successive 1 

 shoots ; but I have heard planters af- : 

 firm that the produce in sugar dimin- 

 ishes from year to year. In Venezu- 

 ela, cane pieces are replanted every I 

 five or six years. | 



" The cane with its top struck off < 

 is carried to the mill, where the juice 

 is expres.sed, and the stems, which 

 are spoken of under the name of trash, { 

 are dried and used as fuel. | 



" The expressed juice contains i 

 crystallizable sugar, an azotized sub- 

 stance analogous to albumen, and j 

 some saline matters dissolved in a : 

 large quantity of water, which is dis- 

 sipated by boiling, and the sugar final- 1 

 ly won by crystallization. The man- j 

 ufacturing process is conducted with 

 very different degrees of perfection [ 

 in different places. In some the prod- [ 

 uce is obtained almost without ad- 

 mixture of molasses, in others the 

 quantity of this article which drains 

 away from the sugar is very large. 

 It is now generally agreed that mo- 

 lasses proceeds in great part from im- 

 perfections in the manufacturing pro- 

 cesses employed, especially to chan- 

 ges which the sugar undergoes in the 

 course of its concentration by boiling 

 at a high temperature. By the em- 

 ployment of what are called vacuum 

 fans of various construction — pans 

 from which the pressure of the at- 

 mosphere is removed either by the 

 air-pump, or the condensation of the 

 vapour as fast as it is formed, rapid 

 evaporation is effected at a tempera- 

 ture much below that of boiling wa- 

 ter, by which it is found that the rel- 

 ative quantity of sugar to that of mo- 

 lasses is greatly increased. It was 

 long believed, indeed, and that on the 

 authority of the first chemists, that 

 there were two kinds of sugar con- 

 tained in the sugar cane, one crys- 

 tallizable, the other uncrystallizable, 

 and constituting the molasses or trea- 

 cle. The researches of M. Peligot 

 have shown definitively that this con- 

 clusion is erroneous ; that the cane 

 contains no sugar that is not crystal- 

 lizable, and that the pre-existence of 

 uncrystallizable sugar or molasses is 

 entirely chimerical. M. Plagne had 

 766 



indeed come to the same conclusion 

 some considerable time ago — as far 

 back as 1826 ; but his labours were 

 not made known by publication till 

 1840. M. Casaseca, professor of 

 chemistry at Havana, has very late- 

 ly confirmed these conclusions, so 

 important for the sugar husbandry of 

 the world. The composition of the 

 juice of the sugar cane is therefore 

 less complex than it was once believ- 

 ed to be ; making abstraction of very 

 minute quantities of an albuminous 

 azotized substance, of several salts 

 and a little silica, substances which 

 altogether do not amount to more 

 than two or three hundredths, cane 

 juice may be said to consist of water 

 and of crystallizable sugar in the pro- 

 portion of from 17 to 20 per cent. The 

 Otaheite cane, analyzed by M. Peligot, 

 actually yielded 



Water , . 72-1 



Woody matter 9-9 



Soluble matter (sugar) . . . 180 



1000 



" This conclusion was verified by 

 ' M. Dupuy at Guadaloupe in 1841, 

 J who, operating on the spot, found the 

 composition to be as follows : 



Water 72-0 



Woody matter 9'8 



Soluble matter (sugar) . . . 17-8 



Salts 04 



1000 



" The analyses of the Creole cane, 

 I made by M. Casaseca at Havana, ap- 

 pear to indicate a larger quantity of 

 woody fibre : 



Water 65-9 



Wood 1614 



Sugar 17-7 



1000 



" The quantity of sugar yielded by 

 the cane differs considerably. M. 

 Codazzi assigns 6 and 15 per cent, 

 as the extremes, and 7^ per cent, as 

 the mean. M. Dupuy gives 7-1 per 

 cent, as the average. The quantity 

 is, of course, first and most intimate- 

 ly connected with the quantity of 

 juice obtained. But the produce of 

 juice is extremely variable. In Gua- 

 daloupe, the juice varies between 56 

 ; and 62 percent, of the cane subjected 

 to pressure. The generality of mills 

 ; do not, in fact, enable us to obtain 

 j more than about 56 per cent. At 



