An Easily Constructed Model of Twin Hexahedral Cones Having a Common Hexagonal Plane Shukichi Yamana Faculty of General Education, Kinki University, Kowakae, Higashi Osaka 577, Japan
A model of twin hexahedral cones having a common hexagonal plane which i s useful for teaching stereochemistry (especially that of lithium nitride LiqN) c a n h e m a d e easilv b y using a sealed e m p t y envelope. he s t e p s are i l l u s t r a t e i i n t h e figure a n d given below. 1) The envelope is folded down the center lengthwise, and the middle point of the hase is marked as C. The center line passing the C, is marked as ( W i n e , hereafter. 2) The lawer part of the envelope is folded up so that the corner B falls on the (C)-line, and the corresponding point on the (C) is marked as D. 3) The new corner on the right-hand side of the envelope is marked as E, and a horizontal line EF, perpendicular to the right-hand side of the envelope at E, is drawn. The intersection of the line EF and the hase AB is marked as G, the corresponding point on the obverse of the envelope being marked as H. 4) The lawer part of the envelope is unfolded. 5) Three middle points of the lines FH, HE, and GB, are marked as I, J , and K, respectively. 6) Three parallel lines with both sides of the envelope, (I)., (H)., and (Kb, are drawn so that each of them passes the ooints I. H. and K, respectively. 7) The intersection of the extension of the line AD and the righthand side of the envelooe is marked as L. 8) The intersection of the'lines FE T.C. . is aa M - and -. .marked -9) The left lower part of the envelope is folded up a t H so that the lower part of the (H)-line falls on the HE line. The corresponding point on the (H)-line, of the point M is marked as N. 10) The left lower part of the envelope is unfolded. 11) A horizontal line, passing the Nand perpendicular to bothsides of the envelope at 0 and S, is drawn. The intersection of this horizontal line OS and each of the (I)-, (C)-, and (K)-lines, are marked as P, Q, and R, respectively. ~
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Journal of Chemical Education
12) The intersection of the two lines AE and (C), is marked as T. 13) A horizontal line is drawn so that it passes the T and intersects the four lines FP, HQ, JR, and E R a t U, V, W, and X, respective-
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14) The lower Dart of the envelooe is folded UD d o n"e the line FE. ~The rorrrsbonding pornts on ;he obverse otfthemvelope, of the I", Q'. R'. points 0, 1'. Q, H. S. U, V. W, and X, are marked as 0'. S'.I]'. V'., W'. and c. t iv. d, < ,--. - -X-' ,-r ~--a n-e-. .. 15) ~ h k f o w e part r of the envelope is unfolded. 16) The lower part of the envelope is cut off along the zigzag course OPVQWRS composed of the six lines OP, PV, VQ, QW, WR, and RS. 17) The upper p a n of the envelope is cut off almg the zigzag course O'l"V'()'W R'S' compused of the sir lines O'P', P'V', V'Q', OW'. \V'R'. and HS'. 181 'khe remaining porlion i~ fdded hoth backward and fwward along the line* FE, Fl". I'V', QW', RE. FP. P'V. Q'W, and R'E. 191 On thr back of the remaining moiety, t h puinls ~ corresponding tothc P.Q. H,U, V, W.X, H. J , P',Q', R', I]', V'. \V',and X', are marked as l".Q'.R',I",V~. We,X'. H',.I'. P",W.R". C". V'*, W", and X'*, respectively. 20) The four triangles PUP*. RXR*. P'U'P'*. and R'X'R'* are cut from the botto&ess envelooe 21) Oblique lines arr draan 10 shnde twelve triangles (PVH, Q\VJ, 1' V'H, and Q'W'J, on the front. P'V'H', Q ' W J ' , P"V"H', andQ"\V".I', on the back; P'I'F. H'Xf.:, I' 'U'F, and R'-X'E. on hoth sides). 22) The lower half of the bottomless envelope is cut along the six lines: UF, VH, WJ, and XE on the front. and V'H* and WaJ* on the back. 23, The right- and left-hand sides of the h
