( 146 ) 
We consider that there is some justification for the assumption 
of the existence of the group of carbon and oxygen atoms, found in 
isodialdane, in the saccharose molecule, the constitution of which is 
as yet unknown. 
Making this assumpticn and using the stereochemical formulae 
of glucose and fructose the following formula is obtained. The left 
half represents the fructose molecule, the right the glucose molecule. 
CH,OH 
| 
DPA 
CS 0 7 CH 
| | 
HOCH _HCOH 
| | 
HC — 0— CH 
| | 
HCOH  HCOH 
| | 
CH,OH HCOH 
| 
CH,OH 
The investigation of isodialdane, which crystallises in two modi- 
fications and is inactive, is to be continued. 
Chemistry. — Prof. H. W. Baknurs ROOZEBOOM presents 
Dr. W. ReiNDersS’ Dissertation on “ Mixed Crystals of 
Mercuric Iodide and Bromide’ respecting which be makes 
the following communication. 
(Read in the meeting of September 30th 1899). 
This research is a second contribution to our knowledge of the 
phenomena which may be observed during the solidification of fused 
mixtures of two substances to mixed crystals and the transformation 
of the mixed crystals into another modification. 
Of the many types, which, according to the theoretical develop- 
ment of the subject given by the speaker, (See Report of the meeting 
of the Academy of Sept. 24th 1898, p. 134) are possible, one of 
the simplest is here realised. 
The meltingpoint line is a continuous curve, showing that 
only one set of mixed erystals is deposited, the composition of 
which changes gradually with that of the fused mass. 
The meltingpoint line, which extends from 236°.5, the melting 
