MEGAK1AN SCHOOL. 



MELLON. 



more prixcd. a dark tortoise-shell hue, they have been known 

 U> srll f or forty or fifty pound* of our money. 



Sine* Dr. Clarke wrote, a change hi* taken place in the manufac- 

 turing amngemenU. Rough Turkish bowk till occasionally come 

 to market; but the meersonsiim U mostly eent to Germany in the 

 form of irregular block*, with obtuae anglei and edge*: requiring 

 careful manipulation with the aid of water to remove irregularibea and 

 Unity portions. Many specimens contain a harder sort of meereehaum, 

 which the Germans call Irridrmauc*, and which u a cause of much 

 difficulty in the subsequent earring. In order to economise the shreds 

 and pannga produced during the manufacture, they are brought to a 

 fine powder, boiled in water, and moulded into blocks with or without 

 the addition of clay. Each of those blocks is afterwards moulded and 

 carved into a bowl. These bowls are distinguished from real meer- 

 schaum by a greater specific gravity ; but in other respects they are 

 mt ranilj 'tt-iit.p.i.K-l 



Some Urge and fine specimens of meerschaum are carved so 

 elaborately into pipe-bowls, aa to command two or three hundred 

 guinea* each. , 



M EG AKIAN SCHOOL. After the death of Socrates the majority 

 of his disciples retired to Megara (' Diog. Laert' ii. 106, iii. 6), where 

 Euclid, one of the oldest of them, resided. [ EUCLID of Megara, in Bloo. 

 Div.l A few of these disciples remained at Megara with Euclid, who 

 was looked upon aa the founder of a school of philosophy which is 

 usually known by the name of Megarian. ID this school the Eleatio 

 philosophy was taught, modified to some extent by the doctrines of 

 Socrates. The Megarian philosophers maintained that the Supreme 

 Good was always the same and unchangeable. They were distinguished 

 in later times by their dialectic subtlety, and by the invention and 

 solution of sophisms; on which account they were called Kriatici 

 (ifurrutvi) and Dialectici (SiaA<*Tuco(). (' Diog. Laert.,' it 1 06.) 



The most celebrated of the successors of Euclid were, Eubulides of 

 Miletus, who opposed certain opinions of Aristotle ; Diodorus, sumamed 

 Cronos, who was originally of lassus in Carls, a pupil of Eubulides, 

 and who lived in Egypt in the time of Ptolemy Soter ; and Stilpo, who 

 was originally of Megara, but afterwards resided at the court of 

 Ptolemy Soter. 



MELA1N. a name which has been given to the colouring matter of 

 the ink of the cuttle-fish. It is obtained pure by evaporating the ink 

 to dryness and boiling the residue successively in water, alcohol, 

 hydrochloric acid, more water, and a little carbonate of ammonia. 

 Dr. Prout found 100 part* of the dry residue of the ink of the 

 cuttle-fish to be composed of Melain, 78' ; carbonate of lime, 10-40 ; 

 carbonate of magnesia, 7'; substance analogous to mucus. 0-84 : various 

 aalU, 2-16. 



This substance has not been further investigated, and its existence 

 as a distinct body must be regarded as problematical. 



MELALEUCA CAJEPITTI (Uoxb.), the ifclalcuca Minor (Smith), 

 a native of the Molucca islands, but cultivated in North- West India, 

 yields the oil termed cajeput It is obtained by distillation of the 

 leans and branches, which are collected the night before they are 

 subjected to this process. It is very limpid, pellucid, and of a light or 

 yellowish green colour. Specific gravity, 0-927 ; it boils at 84SFahr. 

 It is possessed of a penetrating odour ; the taste is acridly aromatic, 

 leaving a sense of coldness in the mouth. Its chemical composition U, 

 carbon 78-12, hydrogen Il-tt, oxygen 10-88. It seems to consist of 

 two distinct oils : one transparent a* water, of specific gravity 0-897; 

 the second dark green, of specific gravity 0-920. Unrectified oil 

 reddens litmus paper, but rectified does not It does not detonate 

 with iodine, nor does it form an artificial camphor with hydrochloric 

 acid pa, but has iU colour much changed by that gas. It never 

 depostU a stoaropten. Some samples of cajeput oil contain copper, 

 which may be detected by shaking the bottle with a solution of ferro- 

 cyanide of potassium ; an artificial oil is also sometimes vended, but it 

 is not difficult to detect the fraud. It is on aromatic stimulant 



EL AM (C.H,N. = 3NCyH t ), Palinc. A compound substance 

 discovered by Uebig. It may be prepared by simply heating sulpho- 

 cyanide of ammonium, or a mixture of sulphocyanide of potassium and 

 ami ammoniac; by their action there are produced three volatile 

 producUandasoUa substance; the three first are ammonia.sulphuretted 

 hydrogen, and sulphide of carbon ; the solid body U a mixture of 

 neJam and chloride of potassium, which are easily separated by 

 washing with water. 



The properties of melam arc : It is a non-crystalline powder, of a 

 grayish white colour, and is insoluble in water, alcohol, or ether ; a 

 boiling solution of potash dissolves and eventually decomposes it; 

 boiling and concentrstnl nitric and sulphuric acid dissolve it, and the 

 solutions, when treated with alcohol, produce a precipitate of ammelide ; 



ben the add solutions are boiled for some hours, the melam is con- 

 into anmumU and cyanuric add. 



> action of beat melam U converted into ammonia and mellon 

 hydrochloric and dilute nitric acid convert it into ammcline and 

 meJamine : and when fused with hydrate of potash, ammoniacal eas 

 and cyaoste of potash are produced. 



It is isomeric with cyanamide. 



MELAMIXE(C.HX-3NCyH). One of the simplest processes 

 for preparing melanin, i. to bofl melam until it diawlve.toa 

 ttoderateljr .Uong solution of potash; when the liquor has been con- 



centrated and cools, melamine separates in orjnUla, and by recrystal- 

 lisation it is obtained in a pure state. 



IU properties are : It crystallises in rhombic octohedrons, which 

 are transparent and colourless, or only slightly yellow. It is very 

 slightly soluble in cold water, but more so in boiling water. It U 

 insoluble in alcohol or in ether, and is unalterable in the air; the 

 aqueous solution has bitter taste, and has no action on vegetable 

 colours. When dry melamine is heated, it fuses, and sublimes almost 

 entirely without decomposing; but a email portion is converted into 

 xui'llon and ammonia. 



Concentrated sulphuric acid and nitric acid decompose it, when 

 heated, into ammonia and ammelide or ammeline. When fused 

 with hydrate of potash, there are produced ammonia and cyanate of 

 !>otash. 



It combines with dilute acids to form salts, all of which have an 

 acid reaction except the double basic salts. The nitrate, phosphate, 

 and oxalate are less soluble than the melamine iUelf ; but the acetate 

 'and foruiiate are very soluble. Melamine precipitates a part of mag- 

 nesia from solution, and forma a double salt with that which remains 

 dissolved. 



It is isomeric with cyanamide. 



MELAMPYIUN, is a crystallised non-azotiscd substance obtained 

 from the cow-wheat, Altlamjtyrum ncmorotum. It is a tasteless neutral 

 principle. 



MELANIC ACID (C M V,O,J. An organic acid resembling lamp- 

 black in appearance, formed from hydride of salicyl. It is insoluble 

 in water, but very soluble in alcohol, ether, and alkaline solutions. 



MELANIL1NE (CjgH^N,). A cyanogen derivative of aniline. 



MELANIN. The black pigment of the eye lias received this name. 

 It is insoluble in water, alcohol, and ether ; but dissolves in. caustic 

 potash with disengagement of ammonia. It contains 



Carbon 57-54 



Hydrogen 5-98 



Nitrogen . 13-77 



Oxygen 22-71 



100-00 



MELANOSIS is a malignant disease distinguished by the deposition 



of a peculiar soft morbid substance, of which the most prominent 



i character is a deep brown or black colour. This substance may be 



' deposited in separate masses, or infiltrated into the tissue of different 



' parts of the body, or it may be effused from the blood in a fluid form 



' into natural or morbidly formed cavities, or separated from it with the 



secretions. The deposition of mclanotic matter generally takes place 



successively in numerous parts of the body, producing in all the 



injurious effects of compression and irritation, till it proves fatal either 



i by its direct influence on some important organ or by the exhaustion 



which it gradually induces. [CANCER.] 



MELANOXIMIDE. [OXAMELANILE.] 



MELANUUENIC ACID. A substance obtained by the action 

 of heat upon urea. It is thought to be identical with ammelide. 



MELANUUIC ACID (C.N.H.O.). An organic acid, obtained by 

 heating urea beyond its melting point : 



4(C,H.N t O,) = C.H.N.O. + 4NHj + 2CO, 



Urea. 



McUnuric acid. 



MELASSIC ACID (C,,H 10 0, ), is formed from cane sugar by the 

 action, of heat and alkalies. It has a very dark colour, and when 

 thrown down by hydrochloric acid appears as a black ftocculeut deposit, 



MELENE. [BEKS'-WAX.] 



MELINUM. [CADMIUM.] 



MKUSSICACID. [MELISSTL.] 



MEL1SSIN. Synonymous with myricylic alcohol. [BEES'- WAX.] 



MELISSYL W '- The h yP tuetical ^^^ of 



acid, one of the family of fatty acids, and obtained by treating myricylic 

 alcohol with soda-lime. The silver salt of this acid has the formula 



MEL1SSYLIC ALCOHOL. Synonymous with myrieylic alcohol 

 [BKES'-WAX.] 



MELITOSE (C.jH.-O,, + 2 Aq.). A saccharkie substance recently 

 extracted from Australian manna. 



MELLIC ACID. [MEI.LITIO ACID.] 



MELLITICACID(C.O,,2HO). A peculiar organic acid hitherto 

 met with only in a rare mineral, the honeyttont, or mellitntc of ammonia, 

 It is crystalline, reddens litmus strongly, and is not decomposed by 

 boiling nitric or sulphuric acid. It has not yet been very completely 

 examined. 



MKLLIMIDE. [PARAMIDB.] 



MELLON (C,,N,,). The formation of crude mellon has already been 

 noticed. [CYANOOEK, mlphocycmogcn.] When it U fused with three 

 times its weight of pure sulphocyanide of potassium a neutral mcllo- 

 nide of potassium is formed, which is very soluble in hot water, but 

 which separates out on cooling in crystals, containing K-,C,,H,, + lOaq. 



From the formula of the above salt, it will be seen that mellon is a 



