138 



HISTORY OF THE VEGETABLE KINaDOM. 



expressed juice is collected and put into boilers, 

 and mixed with a proportion of lime, to absorb 

 the excess of acid ; then it is boiled for some 

 time, care being taken to clear away the scum, 

 which accumulates on the top. When the 

 boiling has been continued sufficiently long to 

 convert the juice into a thickish syrup, it is 

 dra^vn off, and placed in shallow vessels to cool. 

 The thinner part, or the molasses being drawn 

 off by small holes, a mass of crystallized sugar 

 remains. This is the raw sugar of commerce, 

 which has a brown colour and peculiar odour; 

 when further purified it becomes the white or 

 loaf-sugar. Thus obtained, it has a sweet luscious 

 taste, but no smell : when perfectly pure it is 

 white, and somewhat transparent. On exposure 

 to a moist atmosphere, it absorbs moisture; but 

 is not otherwise altered. It is very soluble in 

 water, boiling water dissolving its o^vn weight 

 of sugar. It is soluble in alcohol, and in the 

 acids, though in a less degi-ee. Concentrated 

 acids are capable of decomposing it. Its ele- 

 mentary composition consists of 



Oxygen 64.7 



Hydrogen 7.8 



Carbon 27.S 



100. 



Many other plants contain also a large propor- 

 tion of sugar. The American maple {acer sac- 

 charinum,) at particular seasons of the year, af- 

 fords a juice highly saccharine. For the pur- 

 pose of manufacturing sugar, early in spring a 

 slanting hole is bored in the trunk of the tree, 

 and the juice is collected in pitchers. A tree of 

 ordinary size, will yield from 150 to 200 pints 

 of juice in the season. This juice is mixed with 

 lime, and boiled; when after due evaporation, 

 crystals of sugar are deposited in the proportion 

 of about 1 lb. sugar to 40 pints of sap. The 

 sugar in its qualities nearly resembles that 

 procured from the sugar-cane. Grapes also 

 yield a sugar when treated with potash; but 

 owing to the quantity of acid in the fruit, its 

 taste is not found very agreeable. Common beet 

 root, {bela vulgaris) also yields a large quantity 

 of saccharine juice, which, by skilful manufac- 

 ture, can be made into very good sugar; and 

 during the war with Britain, this manufacture 

 was extensively cultivated in France, by the ex- 

 press commands of Bonaparte, who strictly 

 excluded all products of British colonial impor- 

 tation. Sugar has also been procured from many 

 other plants; from the birch tree, sycamore, 

 bamboo, maise, American aloe, cocoa nut, and 

 walnut ; from the roots of the parsnip, carrot, 

 turnip, cow parsnip, and from tlie nectaries of 

 most flowering plants. The farina of wheat and 

 potatoes, when treated with concentrated sul- 

 phuric acid, will also yield a saccharine pro- 

 duct. 



Sugar is highly esteemed as an article of food 

 not only by man but by most animals. Bees 

 extract it from the nectaries of plants, and store 

 it up in cells where it becomes honey. Besides 

 being highly grateful to the palate, it is found 

 to be a nutritious food; but perhaps more so 

 when combined in the natural state in vegetables, 

 tlian when higlJy concentrated and reiined by 

 the art of man. It was at one time, especially 

 in the form of honey much used in medicine; 

 but has now been found to possess no medicinal 

 virtues, its use being confined to a vehicle for 

 the exhibition of more active drugs. 



Farina or Starch. This substance exists in 

 the seeds and bulbs of many vegetables, and 

 may be readily Qbtained by taking a quantity 

 of wheaten flower, and kneading it under the 

 flow of a stream of water. When the kneading 

 has proceeded so far that the water is no longer 

 tinged of a white colour, this water is allowed 

 to settle, and in a few hours a pure white mass 

 will be found at the bottom, which, when dried 

 and i^owdered, becomes starch. Tliis substance 

 may also be procured by grinding down potatoes 

 in a quantity of water, allowing time for the 

 starch to subside to the bottom, and then pouring 

 off^ the other matters above. Starch is, in its 

 dry state, a fine white powder, tasteless and in- 

 odorous. It is only partially soluble in cold 

 water, and forms with it a white emulsion; with 

 boiling water, it forms a thick and tenaceous 

 paste. If thrown upon a plate of red hot iron, 

 it bums with a slight explosion, leaving scarcely 

 any residuum behind. Its component elements 

 are, 



Carbon 43.55 



Oxygen 49.68 



Hydrogen 6.77 



100. 



On reverting to the analysis of sugar, it will be 

 seen how very nearly both substances coincide 

 in their composition; and, indeed, starch may be 

 converted into sugar by diminishing the propor- 

 tion of carbon, and augmenting that of oxygen 

 and hydrogen. This may be done artificially, 

 by the addition of an acid, as the sulphuric; and 

 is exemplified in the germination of seeds, es- 

 pecially in the conversion of barley into malt. 

 This grain contains a gieat proportion of starch, 

 which, absorbing oxygen in the germinating 

 process, and giving out carbonic acid, is finally 

 converted into sugar. Potatoes also, if exposed 

 to a degree of cold that destroys their vital en- 

 ergy, immediately undergo a fermentation, and 

 their starch is converted into sugar. Starch 

 is also obtained fi-om tlie pith of several species 

 of palms of the Molucca and other East Indian 

 islands. For this purpose, the stems of such 

 palms are cut into longitudinal pieces of six feet 

 in length, so as to expose their pith, which is 



