MERCAPTAXS. 



The table jutt referred to U as followi : 



Number. 

 8-1 415927 



7863982 

 5235988 



8 ._ : 



: 12 -2617994 



: 3 I -. : 



2* - 



4 



1 :0w L68MM 



1 :w -3183099 



4 : 1 :7 . ' 



1 : 4 -0795775 



9-8696044 

 ] 77-24589 

 1-4645919 

 -5641896 

 M2.- 



LofirlthH. 

 04971499 

 0-1961199 



9-7189988 



..,- 

 9.4179688 

 . - " 

 0-7981 799 



W 18801 



0-1049101 

 8-9007901 

 0-9942997 

 0-2485750 

 0-1657166 

 9-7514251 

 0-0524551 

 9-4503951 



'i/(6:irj 1-2407010 0-0986671 



*(3:4) MJH3505 9792C371 



Hyp. log. v 1-1447299 0-0587030 



To find the circumference from the diameter, multiply by T ; to find 

 the diameter from the circumference, multiply by 1 : T ; to find the 

 area from the diameter, multiply the square of the diameter by w : 4 ; 

 to find the area from the radiui, multiply the square of the radius by * ; 

 to find the diameter from the area, multiply the square root of the 

 area by y (4 w) ; to find the area from the circumference, multiply 

 the square of the circumference by 1 : 4 * ; to find the circumference 

 from the area, multiply twice the square root of the area by V ', to 

 find the ordinate perpendicular to a diameter, take the square root of 

 the product of the Mgmenta into which it divide* the diameter. 



To find the area contained between two concentric circles, multiply 

 the product of the sum and difference of the radii by *. 



The arc of a circle and ita subtended central angle are connected as 

 follow* : the arc which U equal to the radius subtends an angle of 57'S 

 rery nearly ; or it may be easily remembered a* 67 degrees and three- 

 tenth* of a degree, diminished by one-fourth of a minute and onc-Jifi/i 

 of a second, being 57* 17' 44"-8, or 206264"'8. To find on angle from 

 It* arc (the radtu* being known), multiply the arc by 57*3, and divide 

 by the radius ; the result U too great by about three-quarters of its 

 1 o,000th part, and is in degrees and decimals of a degree. To find the 

 arc from ita angle, turn the angle into degrees and decimals, multiply 

 by the radius, and divide by 57'8 : the result is now too small by about 

 three-quarter* of ita 10,000th part. 



To find the area of a sector, find the arc (if only the angle be given) 



and multiply it by half the radius. To find the area of a segment 



contained between an arc and a chord, find the sector, and from it 



subtract the triangle formed by the terminal radii and the chord. 



, . . - 



To find the length of an arc, when the radius is not known, measure 

 the chord of the are, and the chord of ita half; from eight times the 

 chord of the half subtract the chord of the whole, and take one-thin 

 of the remainder. For an arc not exceeding 60, the error is leu than 

 the 7000th part of the whole. 



. The preceding are the principal rule* of mensuration, of which the 

 necessity occur* in the elementary part* of the subject : those which 

 remain are connected with solid geometry, and the most essential are 

 M follow* : 



The number of cubic unite in the content of a rectangular solid (or 

 parallelepiped ; there is no shorter term for this most elementary form 

 of solid figure*, unless the reader will follow u* in calling it a right 

 nliti) i* the product of the number of linear unit* in ita three adjacent 

 ides. The content of a priam or cylinder i* the product of the number 

 of square unit* in ita base and the number of linear unite in ita altitude 

 The content of a pyramid or cone i* one-third of the base multiplied 

 by the altitude. The surface* of a prism or pyramid must be found 

 by computing those of their several face*. The surface of a common 

 cylinder (not including the bases) or of a right prism is the circum- 

 ference of the base multiplied by the altitude ; that of a common cone 

 i* half the product of the circumference of the base and the slant xide. 



The following formula: relate to the sphere. To find the surface 

 from the radius, multiply the square of the radius by 4 w,or the square 

 of the diameter by ; to find the content from the radius, multiply 

 the cube of the radiui by 4 *: 3, or the cube of the diameter by : 6 

 to find the radius from the surface, multiply the square root of the sur 

 face by V (1 : 4 ) ; to find the diameter, multiply the square root of 

 toe surface by (1 : w) ; to find the radiu* from the content, multiply 

 the cube root of the content by </(3 : 4) ; to find the diameter, multiply 

 the cube root of the content by .(/($: w); to find the surface from the 

 content, multiply the cube root of the square of six times the content 

 by V ; to find the content from the surface, multiply the square root 

 of the cube of the surface by 1:6 V. [SraMB.1 



For other formula: and method*, the detached article* on the 

 different subjects may be consulted; or Button'* or Bonnycastle'i 



elementary works on mensuration. Many works on mensuration have 

 t*en published of late yean. 



MENTHA ril'KlUTA (Peppermint), a plant common in many 

 part* of Britain, but cultivated lor medical puii<oee*. The dried j.i.mt , 

 which U more powerful than the fresh, is of a lively green, v 

 peculiar aromatic odour, and a pleasant camphor-like taste, at first 

 burning, but at last causing an enduring ensatlm of cold in the mouth. 

 The dried herb is used for the preparation of a distilled water, ami of 

 a volatile oil, from which oil spirit* or essence of peppermint is pre- 

 pared. Of the oil several varieties occur in commerce, the German, 

 Knglish, American, and Chinese. Twenty pounds of the herb yield 

 from four to six drachms ; but if the flowers be also distilled, the same 

 weight will yield four ounces. It is often adulterated with 

 turpentine, oil of marjoram, and absolute alcohol. When pure it is of 

 a whitish yellow, yellow, or even green colour; odour very KI 

 taste burning, camphor-like, causing a sense of coldness in the moutli. 

 The oil is at first limpid, but becomes thicker, like a fixed oil. Kuro- 

 pean oil does not deposit a stearopten, but the American cosily forma 

 long colourless four-sided prisms, which ponscsa the odour of the oil. 

 The American oil ia more soluble in alcohol than the German ; specific 

 gravity 0-92, but when rectified 0'90. The Chinese variety consUta 

 almost entirely of a stearopten. The action on the human system of 

 any of the preparations of mint is stimulant and autinpaaniodic. The 

 oil is used to be added to drastic or griping purgatives, and in cither 

 cases. It proved of considerable utility in bringing about reaction in 

 the collapsed stage of Asiatic cholera. 



MENTHA PULE'GIUM (Pennyroyal), an indigenous spei - 

 mint, smaller than most of the others, and of which the entire herl>, 

 except the root, is officinal. The odour is strong and peculiarly 

 aromatic ; taste herbaceous and bitterish. It has a stimulant and anti- 

 spasmodic property, similar to most mints, but U supposed to possess 

 also a specific power over the uterus, which has been much over- 

 estimated. A distilled water, a spirit, and volatile oil are prepared 

 from it, as from the Alcntha jtipcrita. A popular compound called 

 hysteric water, consists of the distilled water of pennyroyal, and com- 

 pound spirit of bryony, a very unsafe mixture. 



MENTHA VPRIDIS (Spearmint), a plant of Britain, very much 

 resembling M, piperita ; the colour however is of a deep green. It is 

 also frequently confounded with M. Critpa, than which it has a stronger 

 and more agreeable odour, but weaker than peppermint. It has not 

 the aromatic odour of that plant, nor does it leave the sense of coolness 

 in the mouth. From it are prepared a distilled water, a spirit, and a 

 volatile oil, which are used as the former. 



MENTHENE (C M H ls ). A hydrocarbon produced by the action of 

 anhydrous phosphoric acid upon concreted essential oil of mint. It 

 is a transparent fluid oil, possessing an agreeable odour.' 

 MENU. [MANU.] 

 MENUIE. [CoLocnrNQ MATTERS.] 



MENYANTHE8 TRIFOLIA'TA (bog-bean, corrupted into buck- 

 bean, Martli Trefoil, officinal port, the leaves), a plant common in our 

 bogs, and hence called bog-bean, as its leaves resemble the common 

 bean. The leaves are ternate, petiolate, and even when dried have a 

 fine green colour, but are without odour ; they possess an enduring 

 bitter taste. One hundred parts of the fresh herb dry into thirty-nine ; 

 ten pounds of the dried plant yield two pounds and. three-quarters of 

 extract. It contains an extractive (Menyanthin), which Brandes says 

 forms a white, transparent, and, when highly dried, pulverisable mass 

 of an intense degree of bitterness. Troommsdorff says he obtained 

 only a yellowish brown, clear, very viscid, not pulverisablo, bitter 

 extract. 



It is a tonic and febrifuge medicine of undoubted efficacy, but 

 greatly neglected in the treatment of disease. The chief use said to 

 be made of the large quantity annually collected is to substitute it for 

 hops in brewing, a proceeding which U both illegal and detrimental to 

 the beer, since, though bitter, it does not possess the aromatic quality 

 of the hop. 



MENYANTHIN is a non-azotised uncrystallisable neutral principle 

 found in the common buck-bean, Mcnyanthei trifuliata. 

 MEPH1TIC AIR. [CARBONIC ACID.] 

 MERCANTILE MARINE. [Snips.] 



MERCAPTANS. Chemists apply this name to a series of sulphur- 

 alcohols ; that is, alcohols in which the oxygen is replaced by sulphur. 

 The relation of the alcohols to the mercaptons will be most clearly 

 scon by the following comparison of the formula; of vinic alcohol and 

 mercaptan. 



Vinic alcohol. Mercaptan. 



The mercaptann arc produced by saturotiiiK an alcoholic solution nf 

 potash with sulphuretted hydrogen, and then distilling it with the 

 chlorine compound* of the alcohol radicals. Thus vinic mercaptan is 

 produced by the following reaction : 



CA1 - "..}., 



KC1 



SulphhTdrnto 



><! |."' '- 



Chloride of 



ethyl. 



Mercaptan. 



Chloride of 

 poUiriunl. 



