269 



15. Nectar from Nlcotiana afjinis, after dilution to about the 

 threefold of the original volume, was fermented with S. cerevisine. 

 Two drops from the same flower were brought into two small platinum 

 scales and herein the water was added. (The weighings were made 

 with a torsion-balance, accurate (o 0,1 mgr.). The two analyses, 

 made separately gave as results: 33,9 and 34,4 per cent, of sugar 

 in the undiluted nectar; the sugar being calculated as hexose. 



In studying the numbers published here, one will see, that on the 

 whole the results obtained with the microsaccharimeter, were quite 

 satisfactory. Add to this, that sugar determinations by chemical 

 analysis too are of no great accuracy, whilst here we took only a 

 few milligrammes of sugar. For the study of a large number of 

 biological problems the accuracy that was reached here, certainly 

 will be quite sufficient. 



Laboratory for Microscupical Anatomy of the 

 Tpchnical Academy. 

 Delft, July 1915. 



EXPLICATION OF' PLATE. 

 Figure 1. Longitudinal section of the glass apparatus of the microsaccharimeter. 

 Figure 2. General view of the microsaccharimeter (the glass apparatus fixed 



in the cork clamp). 

 Figure 3. Longitudinal section of the neck (enlarged) of the microsaccharimeter, 



filled with mercury, as for the 1th. reading. 

 Figure 4. Auxiliary apparatus, which may be used to place the mercury in the 

 tube and the reservoir on the same level. 



Chemistry. — " Inveatigations on the Temperature-Coefficients of the 

 Free Molecular Surface-Energy of Liquids between — 80° 

 and 1650° C." X. Measurements Relating to a Series of Ali- 

 phatic Coinpounxls. By Prof. F. M. Jaeger and Dr. Jul. Kahn. 



§ 1. For the purpose of comparison of the variations, which 

 occur in the values of the molecular surface-energy of several deri- 

 vatives of the aliphatic series, when simple substitutions ha\e been 

 made in them, it appeared necessary also to investigate in detail the 

 surface-tension and its temperature-coefticient of the following com- 

 pounds : Ethyl-iodide, Etiiylene-chloride, Ethy lidene-chloride, Acetylene- 

 tetrachloride, Acetylene-tetrabromide, Epichlorohydrine,Carl)onbisulphide, 

 Methylalcohol, Formic Acid, Mono-, Di- and Trichloroacetic Acid, 

 Levulinic Acid, Nitromethane, Bromonitro methane, Capronitrile, Di- 

 me thy Is uccinate, Diethylbromoisosuccinate, and Acetylacetone. 



