MON 



MON 



white metal closely allied to tungsten. 

 Its name was derived from the resem- 

 blance of its native sulphuret, or molyb- 

 dena-glance, to lead. 



MOLY'BDIC ACID. Ochry molybde- 

 num. An acid obtained from the native 

 sulphuret of molybdenum, in the form 

 of a yellow powder. Its salts are termed 

 molybdates. The molybdate of lead, or 

 yellow lead ore, occurs as a massive mi- 

 neral, lamelliform, and crystallized in 

 splendid groups on compact limestone, 

 &c. ; chiefly from Bleiberg in Carinthia. 



MOME'NTUM. A term in physics 

 signifying the force of percussion, or 

 the intensity of a moving body ; and 

 this is always equal to the quantity 

 of matter multiplied into the velocity. 

 Thus, a ball of four pounds' weight, 

 moving at the rate of eighteen feet in a 

 second, has double the momentum of a 

 ball of three pounds' weight, moving at 

 the rate of twelve feet per second, for 

 4 X 18 is double of 3 x 12. 



If the momenta of two or more forces, 

 acting in opposite directions on a solid 

 body, be equal, the body will continue 

 at rest ; and this condition is called the 

 equilibrium, or statical momentum of the 

 forces. 



MON-, MONO- (/ioi/of, single, alone). 

 A Greek prefix, denoting unity. 



1. Mon-adelphia {a6e\<p6s, a brother). 

 The sixteenth class of plants in the Lin- 

 naean system, in which the filaments are 

 all united into one tube. 



2. Mon-andria {avi]p, a man). The 

 first class of plants in the Linnaean sys- 

 tem, containing only one stamen. 



3. Mono-carpous {KapKos, fruit). Bear- 

 ing fruit only once, and dying after fruc- 

 tification, as wheat. This is the character 

 of what are commonly called annual 

 plants, and of a few others, which, like 

 the American aloe, although they may 

 live for many years, produce flowers and 

 fruit only once, and then die. 



4. Mono-ceros {Kepa^, a horn). The 

 Unicorn ; a modern southern constella- 

 tion, consisting of thirty one stars. 



5. Mono-chlamydece (x^a/txi)?, a tunic). 

 A sub-class of exogenous plants, in which 

 the flowers have only one envelope, viz. 

 a calyx. 



6. Mono-chord (xop3f/, a string). Sono- 

 meter. An apparatus for exhibiting the 

 phenomena of sonorous bodies and the 

 ratios of their vibrations. In its most 

 simple construction, it consists of a single 

 string of wire or catgut strained by means 

 of two pins across two wooden bridges, 



223 ' 



which are fastened into a strong board ; 

 the part of the board beneath the string 

 is graduated, so that the latter may be 

 readily made to vibrate in any required 

 number of parts. 



7. Mono-chroite. Subsesquichromate 

 of lead ; one of the ores containing chro- 

 mium, occurring with chromate of lead 

 in the Ural. 



8. Mono- chromatic (xpw/xa, colour). 

 Having only one colour ; a term applied 

 to a lamp which, being fed with certain 

 substances, yields a flame of only one 

 colour; and, hence, all objects viewed by 

 this light are deficient in those varied 

 hues which they reflect when viewed by 

 solar light or that from ordinary com- 

 bustibles. 



9. Mono-cotyledons (kotu\»j3u»v, a seed- 

 lobe). Plants which have only one coty- 

 ledon, or seed-lobe. This structure of 

 the embryo corresponds with the endo- 

 genous structure of the stem ; and hence, 

 monocotyledon and endogen are convert- 

 ible terms. 



10. Mon-oecia {oUo^, a house). The 

 twenty-first class of plants in the Lin- 

 nean system, in which the stamens and 

 pistils grow on separate flowers, but on 

 the same individual, as in hazel, birch, 

 oak, &c. 



11. Mono-gram {ypdnfia, a written 

 letter). A mark or cipher consisting of 

 one letter, which is formed by the inter- 

 lacing of two or more letters, employed 

 as an abbreviation, especially on ancient 

 coins. 



12. Mono-gynia {'^wrj, a female). The 

 name given by Linnaeus to those orders 

 of plants, in which each flower contains 

 only one pistil. 



13. Mono-lith {\i9oi, a stone). A pillar 

 consisting of a single stone, as the 

 obelisk of Luxor, the Zodiac of Den- 

 derah, &c. 



14. Mono-mera {fxepof, a part). A sec- 

 tion of homopterous insects, in which the 

 tarsi have only one joint, as in the 

 CoccidcB, or Scale Insects. 



15. Mono-morphous {nop<pri, form). Of 

 a single form; a term proposed by Mr. 

 Westwood for certain neuropterous in- 

 sects, which, in their larva state, are 

 similar in form to the perfect insect, 

 though wingless. 



16. Mono-myaria {/xur, a muscle). A 

 general name for bivalves, whose shell 

 is closed by a single adductor muscle, as 

 in the oyster and the pecten. See Di- 

 myaria. 



17. Mono-neura (vcvpoi/, a nerve). A 



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