258 VARIETIES OF SUGAR. 



pieces, mixing them intimately and gradually with seventeen parts of 

 concentrated sulphuric acid, or with five parts of sulphuric acid, and one 

 part of water: the temperature must be kept moderate. After twenty- 

 four hours the mass is to be dissolved in. a quantity of water, and boiled 

 for ten hours ; it is then to be neutralised with chalk, filtered and 

 evaporated to the consistence of syrup, and crystallised. Chemists have 

 not yet been able to obtain sugar prepared by these artificial methods 

 in regular crystals like cane -sugar, although there is little doubt that 

 these two species differ from each other merely in the quantity of water 

 with which they are combined. 



The plants containing sugar, far from being confined to a single 

 species, are extremely numerous: there has been a long list published 

 of them, and sugar may be extracted in greater or less portions 

 from a vast number. If any form of lignin or woody fibre — for instance, 

 saw-dust (cleansed from 'all foreign bodies, such as resin, extractive 

 matter, &c.) — loe rubbed up with a little sulphuric acid, taking care that 

 the action of the acid does not go to the extent of charring, and if the 

 acid be afterwards abstracted by adding to the mixture an alkali or some 

 powdered chalk, it will be found that the icood has been changed into 

 a species of gum. If we now boil this gum for some hours in acididated 

 water, it gradually becomes converted into sugar. 



Hay, straw, leaves, shavings — in short, any form of ligneous fibre, may 

 be similarly converted ; and although we do this but clumsily and incon- 

 veniently in om 1 laboratories, being as we are but Nature's journeymen, 

 Nature herself carries on these transmutations with the most wonderful 

 results, as we see in the ripening of fruits, where the hard woody texture 

 gradually softens down into sweet and luscious pulp, as in the ripen- 

 ing of the pear, the grape, the strawberry, and, in short, almost all fruits. 



Bracconot, some years since, pointed out the very remarkable fact that 

 saw-dust and linen coidd be converted into grape-sugar, and that from 

 a pound of these substances more than a pound of sugar could be produced. 

 The process is as follows : — "Wood, or linen, or paper, is left to imbibe 

 its own weight of oil of vitriol ; eventually the whole is converted into a 

 viscid mass ; care must be taken that it does not become too hot. This 

 mass being diluted with water is boiled for some hours, the liquor is 

 filtered, the acid removed by chalk, and the sugar formed after eva- 

 poration. One hundred pounds of saw-dust will yield, by this treatment, 

 one hundred and fifteen pounds of sugar; the same quantity of starch 

 may be converted, by a similar operation, into one hundred and six pounds 

 of saccharine matter. These substances only differ chemically from each 

 other by an addition of a small quantity of hydrogen and oxygen, the 

 elements of water, to the latter. The quantity of carbon remains through 

 all the same, but the proportions of the two gaseous elements are increased 

 by the process described. 



The chemical characters of different kinds of sugars are at the present day 

 much studied, and several curious facts concerning them have been brought 



