The correspondence between the calculated and measured (X-ray) lattice parameters of the orthorhombic cell is very good for the a and c axes and fair for the b axis. The comparison does not take into consideration any lattice readjustment, such as homogeneous contraction (or expansion) parallel to certain crystallographic directions, which might take place during transformation. Thus, a homogeneous contraction by 0.015kX. along the b axis of the orthorhombic cell will bring almost exact agreement between the calculated and measured lattice parameters of the orthorhombic phase. Laurie acid (form C or a), C1~H240~, is monoclinic with a = 9.524, b = 4.965, c = 35.39 A.,/? = 129 ° 13'. The cell contains four molecules; density observed 1.032, calculated 1.034 g.cm. -3. The space group is C~-P21/a. Fourier projections were prepared and atomic co-ordinates determined. The angle of tilt T = 54 ° 52'.

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