ALTITUDE. 



ALUMINA. 



the polar regions. Baron Humboldt, in his | wheat, and turnips, whilst a little lower the 



Personal Narrative, gives us a similar account 

 of the several zones of vegetation existing in a 

 height oi' U730 yards on the ascent of Mr-jut 

 Teueriffe. The first /one is the region of vines, 

 extending from the Chores of the ocean to a 



ground is covered with vineyards, groves of 

 apricots, and many aromatic plants. 



The effects of gradual elevation in lessening 

 the falling off of temperature, is manifested 

 upon a moderate scale in our own country. 



height of from 400 to 600 yards, well culti- The [annual] mean temperature of Eastport, 



vated, and producing date trees, plantain 

 t>lives, vines, and wheat. The second zone is 

 .ion of laurels, extending from about 

 000 to 1HOO yards, producing many plants with 

 showy flowers, and moss and grass beneath. 

 The third zone is the region .of pines, com- 

 mencing at 1920 yards, ;i ml having a breadth 

 of 850 yards. The fourth zone is the region 

 littdtna, or broom, L'mwm^ to a height of nine 

 or ten fret, and fed on by wild goats. The last 

 zone is the region of grasses, scantily coYering 

 the heaps of lava, with cryptogamic plants in- 

 termixed, and the summit of the mountain 

 bare. 



Tliis accounts for the great variety of plants 

 which is often found in no great extent of 

 country; and it mav be laid do\vn as a botani- 

 cal axiom, that the more diver-Mied the surface 

 of the country, the richer it will be in species, 

 at [ea.^t in tie- same latitudes. It accounts, 

 the want of correspondence between 

 plants of different . though placed in 



the same latitudes; because the mountains, or 

 ridges of mountains, which may he found in 

 the one and not in the other, will product- tin- 

 greatest possible difference in the character of 

 the genera and species. To this cause we 

 may ascribe the diversity that often actually 

 exists between plants growing in the same 

 country and in the same latitudes; as between 

 those of the north-west and north-east coasts 

 of North America, as also of the south-\\cst 

 and south-east coasts ; the former being more 

 mountainous, the latter more flat. Sometimes 

 the same sort of difference takes place between 

 the plants of an island and those of the neigh- 

 bouring continent ; that is, if the one is flat and 

 the other mountainous ; but if they are alike 

 in their geographical delineation, thoy are 

 generally alike in their vegetable productions. 



[Meteorologists generally compute, that as 

 land rises above the level of the sea or tide- 

 water, the temperature of its climate grows 

 colder at the rate of 1 Fahrenheit, for every 

 300 feet or 100 yards of elevation. It has 

 however been found that the decline of tem- 

 perature on rising above the common level of 

 the sea, is less where large tracts of country 

 rise gradually than when the estimate is made 

 either by balloon ascension, or scaling the 

 sides of isolated, and precipitous mountains. 

 A striking illustration of this is offered by the 

 ridges and valleys of the great I^immaleh 

 mountains of Southern Asia, where immense 

 tracts, which theory would consign to the 

 dreariness of perpetual congelation, are found 

 richly clothed in vegetation and abounding in 

 vegetable and animal life. At the village of 

 Zonching, 14,700 feet above the level of the 

 sea, in lat. 31 36 N. Mr. Colebrook found 

 flocks of sheep browsing on verdant hills ; and 

 at the village of Pui, at about the same eleva- 

 tion, there are produced, according to Captain 

 Gerard, the most luxuriant crops of barley. 



Me., for example, is 4-2.95, whilst that of Fort 

 Snelling in the same latitude, but far in the 

 interior, with an elevation of some 600 or 800 

 feet above the sea, is 2.88 higher, namely, 

 45.83, instead of being two or three degrees 

 colder, to correspond with the law of eleva- 

 tion. (Amer. Med. Jour. July, 1842.)] 



ALUM (Lat. Alurnen'). The sulphate of 

 alumina and potash of the chemist, [or com- 

 mon alum], is composed, according to the ana- 

 lysis of Berzelius (Ann. de Chim. 82 258), of 

 Sulphuric acid - - ... 3423 



Alumina - 1086 



Potash ...... 981 



Water 4500 



99-60 



In veterinary practice, alum in powder is 

 sometimes used externally for destroying 

 trifling excrescences, arresting bleeding, &c. 

 A little, very finely powdered, is occasionally 

 blown through a quill into the eye for the pur- 

 pose of removing specks of long standing. 



Alum lotion is prepared by dissolving from 

 six to eight drachms of alum powder in two 

 pints of water. This forms an inexpensive 

 and tolerably efficacious application for mild 

 forms of grease, cracks in the heels of horses, 

 and for superficial sores of all kinds. It should 

 not be used till the surrounding inflammation 

 has been subdued by time or proper remedies. 

 In its weakest state, the alum lotion is service- 

 able in the cankered ear of dogs, and wounds 

 or ulcers of the mouth in any animal. 



Alum ointment is composed of one drachm 

 of the powder to one ounce each of turpentine 

 and hog's lard, incorporated by heating. This 

 supplies the place of the lotion when the sores 

 are apt to become dry and hard. It is, how- 

 ever, very little used. 



Burnt 'alum is made by boiling a solid piece 

 of the salt on an iron plate over a fire till it 

 becomes quite dry and white, taking care not 

 to make the heat so strong as to decompose it. 

 This, in powder, is sometimes used for specks 

 in the eye. (Miller's Dictionary.} 



ALUMINA. The pure earth of clay, was so 

 named from having been obtained in a state 

 of the greatest purity from alum, in which 

 salt it exists combined with sulphuric acid, 

 and potash. This earth when pure has but 

 little taste, and no smell. The earthy smell 

 which clay emits when breathed upon, is 

 owing to the presence of oxide of iron. Its 

 specific gravity is 2-00. When heated it parts 

 with a portion of water, and its bulk is consi- 

 derably diminished. Hence most day lands 

 are apt to crack, by their contraction in dry 

 weather. There is little doubt, from the expe- 

 riments of Davy, but that alumina is the oxide 

 of a metal, which has been denominated 

 aluminum, although he did not succeed in pro- 

 curing it in a separate state. 



Of all the earths alumina is found in plant 

 in the smallest proportions, 32 ounces of the 



