598 



FARMERS' REGISTER, 



[No, II 



The sap of tlie Birch ( Betiila alba. ) of the 

 Sycamore ( y^cer Pseudoplatamis, ) of the Bam- 

 boo ( yirundo Banibos,') of the Maize ( Zra 

 mays, ) of the Cow Parsnip ( IJeracleum Spondy- 

 lium, ) of the Cocoa-nut tree ( Cocos nucifera. ) 

 of the Walnut tree ( Juglans alba, ) of the Ame- 

 rican aloes (^gave Americana,) of the Dulse 

 ( Fucus Palmatus, ) of the Common Parsnip 

 ( Pastanica sativa, ) of St. John's bread ( Cera- 

 tonia Siliqua ; ) the fruit of the common Arbutus 

 ( Jlrhutus Cnedo, ) and other sweet-tasted fruits ; 

 the roots of the Turnip ( Brassica Papa, ) of the 

 Carrot ( Daitcus Carota ) of Parsley ( j/piuvi pe- 

 iroselimtm, ) the flower of the Euxine Rhododen- 

 dron (^Rhododendron pontictim,) and from the 

 nectarium of most other flowers. 



The nutritive properties of sucar are well known. 

 At the time the British market was over-stocked 

 •with this article from the West India islands, pro- 

 posals were made for applyintf it as the food of 

 cattle ; experiments had been instituted, which 

 proved that they might be fattened by it : but dif- 

 ficulties connected with the duties laid on sugar 

 prevented the plan from being tried to any extent. 

 4. j^lbumen is a substance which has only 

 lately been discovered in the vegetable kingdom. 

 It abounds in the juice of the Papaw-tree ( Cari- 

 ca papaya:) when the juice is boiled, the al- 

 bumen tails down in a coagulated state. It is 

 likewise (bund in mushrooms, and in different 

 species of funguses. 



Albumen, in its pure form, is a thick, jjlairy, 

 tasteless fluid ; precisely the same as the white "oi 

 the egg ; it is soluble in cold water; its solution, 

 when not too diluted, is coagulated by boiling, and 

 the albumen separates in the form of thin flakes. 

 Albumen is likewise coa<rulated by acids and by 

 alcohol : a solution of albumen gives a precipitate 

 when mixed with a cold solution of nutgalls. Al- 

 bumen, when burnt, produces a smell of volatile 

 alkali, and aflords carbonic acid and water; it is 

 therelore evidently principally composed of car- 

 bon, hydrogen, oxygen, and azote. 



According to the experiments of Gay Lussac 

 and Thenard, 100 parts of albumen from the 

 white of the egg are composed of 



Carbon - - 62.88.3 



Oxygen - - 23.872 



Hydrogen - - 7.540 



_ Azote - - - 15.705 



This estimation would authorize the supposition 

 thai Albumen is composed of 2 proportions of 

 azote, 5 oxygen, 9 carbon, 32 hydrogen. 



The principal part of the almond, and of the 

 kernels of many other nuts, appears, from the ex- 

 periments of Proust, to be a substance analogous 

 10 coagulated albumen. ° 



The juice of the fruit of the Ochra ( Hibiscus 

 esculentus,) according to Dr. Clarke, contains a 

 liquid albumen in such quantities, that it is em- 

 ployed in Dominica, as a substitute for the white 

 of eggs in clarifying the juice of the sugar cane. 

 Albumen may be distinguished from other sub- 

 stances by its property of coagulating by the ac- 

 tion of heat or acids, when dissolved in water. 

 According to Dr. Bostock, when the solution con- 

 tains only one grain of albumen to 1000 grains of 

 water, it becomes cloudy by being heated. 



Albumen is a substance common to the animal 

 as well as to the vegetable kingdom, and much 

 more abundant ni the former, I 



5. Gluten may be obtained from wheaten flour 

 by the following process : the flower is to be made 

 into a paste, which is to be cautiously washed, by 

 kneading it under a small stream of water, till the 

 water has carried off" from it all the starch ; what 

 remains is gluten. It is a tenacious, ductile, elas- 

 tic substance. It has no taste. By exposure to 

 air, it becomes of a brown color. It is very 

 slightly soluble in cold water ; but not soluble in 

 alcohol. When a solution of it in water is heated, 

 the gluten separates in the form of yellow flakes ; 

 in this respect it agrees with albumen, but differs 

 from it in being infinitely less soluble in water. 

 The solution of albumen does not coagulate when 

 it contains much less than 1000 parts of albumen : 

 but it appears that gluten requires more than 1000 

 parts of cold water for its solution. 



Gluten, when burnt, aflords similar products to 

 albumen, and probably differs very little from it in 

 composition. Gluten is found in a great number 

 of plants : Proust discovered it in acorns, chest- 

 nuts, horse-chestnuts, apples, and quinces ; barley, 

 rye, peas, and beans ; likewise in the leaves of 

 rue, cabbage, cresses, hemlock, borage, safl'ron, 

 in the berries of the elder, and in the grape. Glu- 

 ten appears to be one of the most nutritive of the 

 vegetable substances ; and wheat seems to owe 

 its superiority to other grain from the circumstance 

 of its containing it in larger quantities. 



6. Gum elastic, or Caoittchmic, is procured from 

 the juice of a tree which grows in the Brazils, 

 called Ha;vea. When the tree is punctured, a 

 milky juice exudes fi'om it, which gradually de- 

 posits a solid substance, and this is gum elastic. 



Gum elastic is pliable and soft like leather, and 

 becomes softer when heated. In its pure state, it 

 i.s white ; its specific gravity is 9335. It is com- 

 bustible, and burns with a white flame, throwing 

 off a dense smoke, with a very disagreeable smell. 

 It is insoluble in water and in alcohol; it is solu- 

 ble in ether, volatile oils, and in petroleum, and 

 may be procured from ether in an unaltered state, 

 by evaporating its solution in that liquid. Gum 

 elastic seems to exist in a great variety of plants : 

 amongst them are, Jatropha elastica, Picus in- 

 dica, j^rtocarpus integrifolia, and Urceola elastica. 

 Bird-lime, a substance which may be procured 

 from the holly, is very analogous to cum elastic in 

 its properties. Species of gum elastic may be ob- 

 tained from the misletoe, from gum-mastic, opium, 

 and from the berries of the Smilax caduca, in 

 which last plant it has been lately discovered by 

 Dr. Barton, 



Gum elastic, when distilled, affords volatile 

 alkali, water, hydrogen, and carbon, in diflerent 

 combinations. It therefore consists principally of 

 azote, hydrogen, oxygen, and carbon ; but the 

 proportions in which they are combined, have not 

 yet been ascertained. Gum elastic is an indiges- 

 tible substance, not fitted for the food of animals ; 

 its uses in the arts are well known.* 



7. Extract, or the extractive principle, exists 

 in almost all plants. It may be procured in a state 

 of tolerable purity from saffron, by merely infus- 

 ing it in water, and evaporating the solution. It 

 may likewise be obtained from catechu, or Terra 

 japnnica, a substance brought from India. This 



* By a very carefid distillation, a very volatile fluid 

 may be obtained from it, of sp. gr. 0.64 : it is a powerful 

 solvent of caoutchouc, and of the resins used in the 

 preparation of varnishes. — J. D. 



