AMM 



AMM 



branches the flowers are produced in 

 small umbels ; these are of a fine blue co- 

 lour, as are also the upper part of the 

 branches, and the leaves immediately un- 

 der the umbel; so that though the flow- 

 ers are small, yet, from their colour, with 

 that of the upper part of the stalks, the 

 plants make a pretty appearance during 1 

 their continuance in flower. 



AMIA, in natural history, a genus of 

 fishes of the order Abdominales. Gene- 

 ric character : head bony, naked, rough, 

 with visible sutures. Teeth, both in jaws 

 and palate, close-set, sharp, numerous. 

 Cirri or beards two, near the nostrils. 

 Gill-membrane twelve-rayed: body sca- 

 ly. There is a single species, Calva, a 

 small fresh water fish, inhabiting some 

 parts of Carolina, of which the tail is 

 rounded, and with a black spot ; it is sel- 

 dom eaten. 



AMIABLE, or amicable numbers, such 

 as are mutually equal to the sum of one 

 another's aliquot parts, as the numbers 

 284 and 220. 



Van Schouten was the first who gave 

 this name to such numbers, of which there 

 are but very few at least to be set down 

 and manageable by us. For 284 and 220 

 are the two least. " The aliquot parts of 

 220 are 1, 2, 4, 5, 10, 11, 20, 22,44, 55, 110, 

 and the sum of these is equal 284. The 

 aliquot parts of 284 are 1, 2, 4, 71, 142, 

 and the sum of these is 220. The second 

 pair of applicable numbers are 17296 and 

 18416. The third parr are 9363584 and 

 9437056. 



AMIANTHUS. See ASBESTOS. 



AMICUS cin-ite, in law, if a judge be 

 doubtful or mistaken, in a matter of law, 

 a bystander may inform the court as ami- 

 c.us curioE. 



AMMANNIA, named by Houstoun in 

 honour of J. Amman, in botany, a genus 

 of the Tetrandria Monegynia class and 

 order. Its characters are, that the calyx 

 is a perianthium, bell-shaped, oblong, 

 erect, with eight streaks and folds, quad- 

 rangular, eight-toothed, teeth alternate, 

 bent in, and permanent ; corolla none, or 

 four-petalled, petals vertically ovate, 

 spreading, inverted into the calyx ; the 

 stamina have filaments, (four or eight) 

 bristly, the length of the calyx into which 

 they are inserted, anthers twin ; the pistil- 

 lutn is a germ, subovate, large and supe- 

 rior, style simple, very short, and stigma 

 headed ; the pericarpium is a roundish, 

 four-celled capsule (bury) covered with 

 the calyx ; the seeds are numerous and 

 small. 



AMMI, ?y>o/V rwf/, in botany, a dis- 



tinct genus of umbelliferous plants, be- 

 longing to the Pentandria Digynia class 

 of Linnaeus ; the flower of which is rosa- 

 ceous, and composed of heart -like petals ; 

 and its fruit is a small roundish and stri- 

 ated capsule, containing two striated 

 seeds, convex on one side, and plane on 

 the other. There are four species. 



AMMODYTES, in natural history, the 

 launce, a genus of fishes, of the order 

 Apodes : head compressed, narrower than 

 the body : upper lip doubled : lower jaw 

 narrow, pointed: teeth small and sharp. 

 Gill-membrane seven-fayed : body long, 

 roundish, with very small scales : tail dis- 

 tinct. A. tobianus, or sand launce, so 

 named from its shape. It inhabits the 

 northern seas ; and is from 9 to 12 inches 

 long. It buries itself on the recess of the 

 tides a foot deep in the sand, and in fine 

 weather rolls itself up, and lifts its nose 

 just above the sand ; it is the prey of 

 other rapacious fish ; the flesh is tolerably 

 good, but it is used in most cases as baits, 

 The launce lives on worms, water-insects, 

 and small fishes, and even occasionally on 

 those of its own species. The mackarel 

 is very partial to this fish as its own food. 

 The launce spawns in May, depositing- 

 its eggs in the mud near the edges of the 

 coast. 



AMMONIA, in chemistry. Volatile al- 

 kali, in its purest form, subsists in a state 

 of gas, and was thought, till the late expe- 

 riments of Mr. Davy, to be composed of 

 azote and hydrogen. It maybe obtained 

 in the following manner : put into a retort 

 a mixture of three parts of quick-lime and 

 one part of sal ammoniac in powder. 

 Plunge the beak of the retort below 

 the mouth of a glass jar filled with mer- 

 cury, and standing inverted in a basin of 

 mercury. Apply the heat of a lamp to the 

 retort : a gas conies over, which displaces 

 the mercury and fills the jar. This gas 

 is ammonia. It was known by the name 

 of volatile alkali ; it was also called harts- 

 horn, because it was often obtained by 

 distilling the horn of the hart ; spirit of 

 urine, because it may be obtained by the 

 same process from urine ; and spirit of 

 sal ammoniac, because it may be obtained 

 from that salt. Dr. Black first pointed out 

 the difference between ammonia and car- 

 bonate of ammonia, or ammonia combined 

 with carbonic acid; and Dr. Priestley dis- 

 covered the method obtaining it in a 

 state of purity, by the process already 

 described. Ammonia, in a state of gas, 

 is transparent and colourless like air; its 

 taste is acrid and caustic, like that of the 

 fixed alkalies, but not nearly so strong, 



