396 [Jan. 15, 



the plane 1 0, and they make with each other a small angle which 

 is bisected by the line [100]. 



A crystal having two opposite faces of the form 110 much larger 

 than the two remaining faces, being immersed in oil for which 

 /u = 1*4793, and placed in a polarizing apparatus, the rings sur- 

 rounding the optic axes were seen through the large faces of the 

 form 110. The angle included between the directions of the optic 

 axes within the oil was about 4. 



III. "On the Synthesis of Leucic Acid/' By Dr. EDWARD 

 FRANKLAND, F.R.S. Received December 26, 1862. 



When oxalic ether is mixed with more than its own weight of 

 zincethyl, the temperature of the mixture slowly rises, and soon 

 considerable quantities of gas begin to be evolved, unless the heat 

 be moderated by plunging the vessel, in which the reaction takes 

 place, into cold water. The gas consists of equal volumes of ethylene 

 and hydride of ethyl ; and as it is the product of a secondary decom- 

 position, its evolution should be avoided as much as possible in the 

 manner just indicated. The final application of a gentle heat com- 

 pletes the reaction. 



The mixture generally continues fluid, but it becomes of a light straw- 

 colour, and of an oily consistency. On being heated to 130 C. in a 

 retort, no distillate passes over. If, after cooling, its own volume of 

 water be very gradually added to it, torrents of hydride of ethyl, 

 derived from excess of zincethyl, are evolved. By subsequent distilla- 

 tion in a water-bath, weak alcohol containing an ethereal oil in solu- 

 tion passes over ; and a further quantity of k the oil may be obtained by 

 adding water to the residue in the retort, and continuing the 

 distillation upon a sand-bath. The ethereal oil was precipitated 

 from the alcoholic distillate by the addition of water, and was added 

 to that which floated upon the surface of the aqueous distillate. It 

 was then dried over chloride of calcium, and rectified. A very large 

 proportion of the liquid distilled between 174 and 176C., and was 

 collected apart. 



Numerous analyses of this liquid agree closely with the formula* 

 C H 16 3 . 



* C = 12, = )6. 



