34 SECTIONAL ADDRESSES 
The mutarotation of nitrocamphor, always from left towards right, could 
therefore be attributed to a partial conversion in solution of levorotatory 
nitrocamphor into a dextrorotatory isomeride, containing an acidic 
hydroxyl group, which was capable of forming an anhydride as well as a 
series of salts. 
CH.NO, C=NO,H C=NO,K 
C,H mecca O4 Fl Femme 51 | 
8 wl tg 8 wl 4 8 wt fey 
Nitrocamphor. y-Nitrocamphor. Potassium salt. 
Jt 
CBr.NO, ghd bale 
C,H | C,H | | SC,Ay 
8 Lp cil 8 ates oct atty 
Bromonitrocamphor. Anhydride of nitrocamphor, 
At this stage Prof. Kipping very generously gave me a quantity of 
the ~-bromo-derivative of «-bromonitrocamphor, from which I was able 
to prepare a stock of x-bromonitrocamphor. Lapworth and Kipping (12) 
had described this compound as trimorphous, and had recorded the 
crystal-constants and published drawings of two of the forms. The 
orthorhombic form, melting at 142°, proved-to be strongly dextrorotatory 
when dissolved in benzene, but it became levorotatory after a few hours. 
The tetragonal form, melting at 108° (which is formed as a by-product, 
alongside the more stable form, by rapid evaporation of a solution in 
chloroform), was found to be levorotatory, but like nitrocamphor it 
exhibited a relatively small mutarotation from left towards right. ‘This 
labile form was therefore analogous with ordinary nitrocamphor, whilst 
the more stable form was analogous with the still unknown pseudo- 
nitrocamphor, the relative stability of the two isomers having been 
reversed by the introduction of a halogen. The third form, for which no 
crystal measurements had been published, was evidently a mere mixture 
of these two isomers (13). 
The mutarotation of the sugars in aqueous solutions had been 
attributed to several causes ; but, when Emil Fischer (14) observed the 
same phenomenon during the reversible hydrolysis of the sugar-lactones, 
he concluded that these changes of rotatory power were due to reversible 
hydration, and this conclusion was very widely accepted. 
C,H,,O, + H,0 == C,H,2.0, 
Gluconic Gluconic 
lactone. acid. 
CoO, + HO == = C.HyO, 
Anhydrous Glucose 
glucose. hydrate. 
This explanation can obviously be applied to any aqueous solution in 
which reversible hydrolysis can take place ; but it was not applicable to — 
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