CHEMISTRY. 



107 



Nature. 



How ob- 

 tained. 



It proper 

 tiet. 



astringent tasted trees, as elm, oak, horse-chcsnut, beech, 

 willow, elder, plum, sycamore, birch, cherry-tree, moun- 

 tain-ash, poplar, hazel, ash, sumach. 



7. Benzoic acid has been found only in a few vegeta- 

 ble substances, to wh'ch the name of balsam has been 

 given. The chief of these are benzoin, balsam of Tola, 

 siorax, dragon's Hood. 



8. Prussic acid has been found in the leaves of the 

 L'turo ceraxus, in peach blossoms, in the flowers of the 

 sloe, in the leaves of the bay-leaved willow (salix pen- 

 tandrn], and in most bitter tasted kernels. 



9. Phosphoric acid is very common in plants, but on- 

 ly in small quantities, aud it is usually combined with 

 p'otash or lime. Phosphate of potash exists in barley 

 and other species of corn, so does phosphate of lime. 

 Both of these salts exist in the leaves of many trees. 



SECT. II. Of Sugar. 



Common sugar is obtained from the juice of the arun- 

 <lo sncharifcra or sugar cane, a plant cultivated from 

 time immemorial in India and China. It was unknown 

 in Europe till after the conquests of Alexander the 

 Great. The cultivation of the sugar cane was gradual- 

 ly introduced into Sicily and Spain, and, after the dis- 

 covery of America, it was imported to the West Indian 

 inlands, where it has been cultivated to a great extent. 

 Sugar has, in consequence, become a necessary of life 

 among the modern nations of Europe. 



The juice is extracted by passing the cane between 

 iron rollers, and immediately run into a flat copper caul- 

 dron, where it is mixed with a little lime, and heated to 

 the temperature of 11-0. A thick viscid scum collects 

 on the surface, which is left unbroken, and the clear li- 

 quid drawn from below and introduced into a large boiler. 

 Here it is boiled briskly, the scum, as it forma, being 

 constantly removed. From this first boiler it is passed 

 into a second, from that to a third and fourth, in each 

 of which the boiling is continued. When sufficiently 

 concentrated, it is poured into a large wooden vessel 

 called the cooler, where it crystallizes or grains as it 

 cools. From the cooler it is taken and put into hogs- 

 heads, having a hole in the bottom, into which the stalk 

 of a plantain leaf is thrust. Through these holes the 

 molasses drain into a receiver. The sugar, thus cleared, 

 is brought to this country under the name of raw sugar. 

 It is refined by solution in water, clarified by bullock's 

 blood, boiled down and poured into earthen cones, ha- 

 ving a hole in the apex which is undermost. The base 

 of the cone is covered with moist clay. From this the 

 water slowly penetrates through the sugar, and carries 

 nff the impuritie*. In this state it is white, and is known 

 by the name of loaftugar. 



From the experiments of Proust, it appears that su- 

 gar cane juice contains gluten, gum, extractive, a little 

 malic acid, sulphate of lime, and two species of sugar. 

 The object of the process is to remove all the substances, 

 except the crystallizable sugar. 



Sugar is a firm white substance, of an extremely sweet 

 taste, but destitute of smell. It is but little altered by 

 exposure to the atmosphere, though in damp air it is 

 liable to become moist. 



Cold water dissolves nearly its own weight of sugar, 

 and boiling water dissolves any quantity whatever. The 

 olution constitutes a thick, ropy, adhesive fluid, called 

 syrup. When syrup is sufficiently concentrated, and 

 kept in open vessels in a hot place, the sugar gradually 

 crystallizes. The crystals are four or six-bided prisms, 



terminated by two-sided, and sometimes by three-sided Chemical 

 summits. 



The specific gravity of white sugar is 1.6065. It is 

 not acted on by oxygen gas, by the simple combustibles, , 

 by azote, or by the metals. The alkaline earths com- 

 bine with sugar, and form a compound which has a bit- 

 ter and astringent taste. Sugar facilitates the solubility 

 of lime and strontian in water ; but barytes appears to 

 act with more energy, and to occasion decomposition of 

 sugar. The fixed alkalies combine with sugar, and 

 form compounds similar to those formed by the alkaline 

 earths. 



The acids dissolve sugar, and the more powerful mi- 

 neral acids decompose it. Nitric acid dissolves it with 

 effervescence, converts one half of its carbon into carbo- 

 nic acid, the residue assumes the form of water and oxa- 

 lic acid. A quantity of malic acid is also evolved. 100 

 grains of sugar yield, by this treatment, 58 grains of 

 oxalic acid. Sulphuric acid decomposes sugar, water 

 and acetic acid are formed, and a great quantity of char- 

 coal evolved. 



Sugar dissolves in about 16 parts of boiling alcohol, 

 If the solution be set aside, the sugar is gradually depo- 

 sited in elegant crystals. 



The hydrosulphurets, sulphurets, and phosphurets of 

 alkalies and earths, seem to have the property of decom- 

 posing sugar, and of bringing it to a state not very dif- 

 ferent from that of gum. 



When heat is applied to sugar, it melts, swells, be- 

 comes brownish black, emits air bubbles, and emits the 

 smell of caromel. At a red heat it bursts into flames 

 with a kind of explosion. When distilled, there comes 

 over water ; an acid liquid, called pyromiicous acid, now 

 known to be the acetic mixed with a little empyreumatic 

 oil ; an oil, and a bulky charcoal, remains in the retort. 

 During the distillation a considerable quantity of carbo- 

 nic acid and heavy inflammable air come over. 



From the experiments of Lavoisier, compared with Composi- 

 some of our own, it appears that sugar is composed of ti<>n ac - 



64. oxygen cording to 



Lavoisier. 

 28 carbon 



8 hydrogen- 



100 



According to the experiments of Thcnard and Gay- According 

 Lussac, the constituents of sugar are as follows : t Gay- 



Oxygen, 50.65? Luisat ' ' 



Carbon, 42.47 

 Hydrogen, 6.90 



100 



It appears from the recent researches of chemists, thai Different 

 there exist various species of sugar differing from each kinds i 

 other in their properties. The most important of these sugar, 

 are the following : Common sugar, liquid sugar, sugar 

 of grapes, sugar of beet, manna. 



Common sugar is the substance described in the pre- 

 ceding part of this Chapter. It is obtained from the su- 

 gar cane. The properties of the sugar of the maple are 

 not known to differ from those of common sugar. 



Liquid sugar was first pointed out by Proust. It ex- 

 isto in a variety of fruits and vegetable juices. It does 

 not crystallize, and can only be exhibited in a liquid 

 state. It is more soluble in alcohol than common sugar, . 

 It exists in the juice of the sugar-cane, and constitutes 

 no inconsiderable portion of tnoKuses: 



Sugar was first extracted from grapes by the Due de 

 Bullion. They often yield, according to Prcust, fiom 



