TABLE 2. Parallelism between the sign of the rotation and the configuration of the sugar 



lactones Continued . 



The table shows that among these 24 sugar lactones (which include 

 all the known substances for which there are sufficient data known 

 to test the hypothesis) there is not a single exception to the theory, 

 all the lactones which have the ring "above" the chain are levoro- 

 tatory and all having it " below" the chain are dextrorotatory. 



APPLICATION OF THE THEORY TO DETERMINE THE CONSTITU- 

 TION OF THE SUGARS. 



As this relation between the stereo position of the lactonic ring and 

 the sign of the rotation of the lactone is well founded, it may be used 

 in determining the constitution of the sugars. For some of the 

 sugars such a determination is only a tracing backward of the steps 

 of the above experimental proof of the hypothesis, but for certain 

 others (e. g., rhamnose) this method gives entirely new data on the 

 constitution, as will be shown. In determining the constitutions of 

 the sugars Emil Fischer has used most ingeniously a mass of chemical 

 data of various kinds, nearly all of which he worked out in his own 

 laboratory. In what follows it will be shown that the constitutions 

 of the monose aldehyde sugars can be independently determined 

 from two kinds of experimental data: (1) A knowledge of the sugars 

 which results from the cyanid synthesis or its reverse; and (2) a 

 knowledge of the signs of the rotations of the lactones of the mono- 

 basic sugar acids. This second kind of data can not be obtained for 

 the ketone sugars, because they do no.t yield acids and lactones, and 

 their structure can not be found by this method alone. 



The stereo configuration of d-glucose. The cyanid synthesis or its 

 reverse has shown the steps of the following series: d-erythrose > 

 d-arabinose > d-glucose d-glucoheptose > d-gluco-octose. The 



[Cir. 49.] 



