ALK 



ALL 



fractional exponents, over the right: 



as a3 is the same as 'XJ a. 

 00 Indefinitude, denotes that the quan- 

 tity before which it is put, is greater 



or less than any value that can be 



assigned : as ^, or \. 



A'LGENIB. A star of the second 

 magnitude, on the right side of Perseus. 



A'LGOL. Medusa's Head. A variable 

 star in the constellation Perseus. 



A'LGORAB. A star of the third mag- 

 nitude, in the right Aving of Corvus. 



A'LGORITHM. An Arabic term ex- 

 pressing numerical computation, and now 

 generally used to denote the operative 

 part of arithmetic or of algebra, 



A'LIFORM {ala, a wing, jhrma, like- 

 ness). Wing-like; shaped like a wing. 



A'LILADE. An Arabic term for the 

 index which traverses the centre of an 

 astrolabe or quadrant, carrying the sights 

 or telescope, and indicates on the limb of 

 the instrument the number of degrees 

 and minutes which an object is elevated 

 above the horizon. 



A'LIQUOT PART {aliquot, some). 

 A number which divides a given num- 

 ber without leaving a remainder : thus, 

 2, 4, 5, and 10 are aliquot parts of 20. All 

 the aliquot parts of any number may be 

 thus found :— divide the given number 

 by its least divisor; then divide the quo- 

 tient also by its least divisor; and so on, 

 always dividing the last quotient by its 

 least divisor, till the quotient 1 is ob- 

 tained ; all the divisors thus taken are 

 the prime aliquot parts of the given 

 number. 



ALISMA'CEiE. The Water-Plantain 

 tribe of Monocotyledonous plants, named 

 from the genus Alisma. Floating plants, 

 having leaves with parallel veins ; petals 

 and sepals 3 ; stamens definite or indefi- 

 nite ; ovaries superior ; fruit dry, indehis- 

 cent; seeds ex albuminous ; e/n6r^o shaped 

 like a horse-shoe. 



A'LIZARIN. A peculiar colouring 

 principle obtained from madder, and 

 named from alizarin the connmercial 

 name for madder in the Levant. 



AL'KAHEST. An Arabic term, de- 

 noting the pretended universal solvent 

 or menstruum of the old chemists. 



ALKALE'SCENT. A term applied to 

 substances on which alkaline (ammo- 

 niacal) properties are beginning to be 

 developed, 



ALKALI PRUSSIAN. Phlogisticated 



alkali. A name formerly given to a fixed 



alkali, when ignited with some animal 



substance, and lixiviated. It is found 



17 



to be in a great measure saturated with 

 Prussic acid, 



A'LKALIES {al, the Arabic definite 

 article, and kali, the name of a plant 

 from which the alkali is obtained by 

 burning, and an old name for potash). 

 A class of bodies, which possess a strong 

 acrid and powerfully caustic taste, and 

 exercise a corrosive action upon all 

 animal matter; they turn the infusions 

 of blue vegetable colours to green, and 

 combine with the various acids, forming 

 an extensive class of compounds called 

 salts. There are three alkalies : 



1. The Vegetable, f^J^fi^'d alkalies, 



or Potash, bemg/e/^mthe ^ 



2. The Mineral, Y T '", 



or Soda, . and marme plants 



*- respectively. 



3. The Animal, or Ammonia, or vola- 

 tile alkali, being raised by distillation 

 from hartshorn, &c, 



ALKALI 'METRY {alkali, and nerpov, 

 a measure). The method by which the 

 value of the alkalies, or carbonated alka- 

 lies, is determined. By means of an in- 

 strument, called an alkalimeter, the 

 quantity of alkali in a given substance is 

 ascertained by the quantity of dilute sul- 

 phuric acid of a known strength which 

 a certain weight of them can neutralize. 



A'LKALINE AIR. The term by 

 which Priestley first described ammonia, 

 or ammoniacal gas, the volatile alkali. 



A'LKALINE EARTHS. A term ap- 

 plied to magnesia, lime, baryta, and 

 strontia, from their earthy character and 

 alkaline properties. 



ALKALFNITY. The property of an 

 alkali, viz. that of turning vegetable 

 blues into green. 



ALKALIZA'TION, The impregna- 

 tion of any substance with an alkali. 



A'LKALOIDS {alkali, eJdoi, likeness). 

 Vegeto-alkalies. A general term for cer- 

 tain bodies containing nitrogen, which 

 have the properties of the basic or me- 

 tallic oxides, and form salts with acids. 

 They are produced in plants during vege- 

 tation, 



A'LKANET. A reddish purple dye, 

 obtained fron the roots of the Anchusa 

 tinctoria. 



A'LKER. A star of the third magni- 

 tude in the constellation Crater. 



A'LLAGITE A mineral of a brown 

 or green colour, consisting of a carbo- 

 silicate of manganese. 



A'LLANITE. A mineral containing 

 cerium, found in Greenland, and named 

 from Mr. Allan. 



