216 Mr Jackson, Researches in the Sugar Group. 



(/3) Isolation of Diose in a crystalline state and its condensa- 

 tion to a Hexose. 



When dioxymaleic acid, suspended in water, is distilled on 

 the water bath under very diminished pressure and the distillate 

 evaporated to small bulk in a vacuum desiccator, a syrup is left 

 which on standing crystallizes out in flat plates of the oblique 

 system. On analysis and examination it is shewn to be crystalline 

 diose. A determination of its molecular weight by the depression 

 of the freezing point of water shows the crystals to be bimolecular, 

 but on standing and taking frequent determinations the molecular 

 weight gradually becomes normal and corresponds to the single 

 formula C 2 H 4 2 and then remains quite constant. 



If a dilute aqueous solution of diose be treated with a l°/ 

 solution of soda at the ordinary temperature it quickly turns 

 yellow and finally brown. After standing a few hours it no longer 

 reduces Fehling's solution in the cold, but readily on warming : 

 it no longer gives the " magenta " test : in fact it has lost all the 

 properties of diose and assumed those of a true hexose. This is 

 confirmed on examining the osazone which corresponds to a normal 

 hexosazone. 



The melting point and action towards solvents of the osazone 

 prove its identity with ft acrosazone which Fischer and Tafel 

 isolated from the condensation product of glycerose. 



On a New Mineral. By Mr A. Hutchinson. 



[Read 27 November, 1899.] 



A colourless transparent crystal of the new mineral was found 

 on a specimen of Axinite from Cornwall in the Carne collection 

 recently acquired by the University. 



The crystallographic and optical constants of the crystal prove 

 it to belong to the Prismatic system. The results of a quantitative 

 chemical analysis agree well with the formula CaSn(Si0 3 ) 3 .2H 2 0. 



The mineral has been named Stokesite in honour of Sir George 

 Gabriel Stokes. 



