202 EXPERIMENT STATION RECORD. [Vol.40 



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and of the invertase extracted from various Saccharomyces or Penicilia. The 

 coincidence of progressive inactivation with progressive coagulation is consid- 

 ered to be attributable only to the influence of heat on the degree of dispersion 

 of the inverting colloid. 



The constitution of pectin bodies, T. vox Fellenberg (Biochcm. Ztschr., 85 

 {1918), No. 1-2, pp. 118-161). — A r6suin6 of the literature on the pectin bodies 

 is given, followed by a report of a detailed study of the three classes of pectins — 

 protopectin, pectin, and pectic acid — occurring in unripe, ripe, and overripe 

 fruits, respectively. The properties observed are recorded in tabular form, 

 including the constitution; solubility; behavior with ammonia, sodium hydroxH 

 and other electrolytes, tannic acid, protein, and dyes; and ability to form jelly. 

 On heating with sugar and pectin-free fruit juices only the second form of 

 pectin was able to form jelly. 



Attention is railed to the fact that the so-called bassorin of gum tragacanth 

 also yields methyl alcohol on treatment with solium hydroxld and is converted 

 into bassoric acid, which resembles pectic acid in certain of its proj 



Crystallography and optical properties of three aldopentoses. E. T. Whkkky 

 (Jour. Amer. Chem. Soc, 40 (1918), No. 12. pp. t85£ 1858, figs. 5).— The author, 

 at the Bureau of Chemistry pf the U. S. Department of Agriculture, reports 

 the results of an examination of the crystallographic and optical properties of 

 the aldopentoses, art-xylose, a-d-lyxose, and /3-r/-arabinose. A determinative 

 table is given by means of which It is said to be possible to distinguish the 

 sugars of this group through differences in optical properties. 



On constituents of oil of cassia, II, F. D. Dodge (Jour. Indus, ami Emjin. 

 Chem., 10 (1918), No. 12, pp. 1005, 1006).— In addition to the constituents of oil 

 of cassia previously noted (E. S. R.. 34, p. 501), the author has isolated from 

 the oil benzaldehyde and methyl Ballcylaldehyde. 



Experiments with an isomer of caffein. W. Sai.ant and Helene ('onnet 

 (Proc. Soc Expt. Biol, and Med., 15 (1917), No. 1. p. 9). 



Simplification of the technique of gasometric determinations. A. Ren Am 

 (Jour. I'h'irm. el (him.. 7. •«"., 18 (1918), No. -J, pp. 10.',-W6; aba. in Jour. SoO. 

 Chem. Indus.. 37 (1918), No. 22, p. 719A). — For the determination of urea in 

 urine a standard volume of air equal to the volume of nitrogen obtained from a 

 definite weight of urea is kept for comparison with the volume generated from 

 a definite volume of the urine under examination. The use of a similar stand- 

 ard is recommended for the gasometric examination of ammonium salts, car- 

 bonates, etc. 



An accurate method for measuring the density of gases. O. Ma ass and J. 

 Russell (Jour. Amer. Chem. Soc. 1,0 (1918). No. 12, pp. 1847-1852, fig. 1).— The 

 method described is applicable to gases which can be condensed by liquid air 

 or some other freezing agent. A known volume of gas at known pressure 

 and temperature is liquefied in a small bulb attached to the containing vessel, 

 the bulb is sealed off. and the liquefied gas is weighed at room temperature. In 

 this way a large quantity of gas can be weighed on a small sensitive balance 

 and in a vessel whose weight is of the same order as that of the gas itself. 



A special stopcock for dropping liquids arranged for equalizing the pres- 

 sure above and below the outlet in the stopcock, H. L. Fisher (Jour. Indus, 

 and Engin. Chem., 10 (1918), No. 12, pp. 101k, 1015. fig. 1).—A stopcock is de- 

 scribed and illustrated which was designed in connection with a generator for 

 carbon diozld to be used alternately with pressures below and above atmos- 

 pheric. 



On the quinone phenolate theory of indicators. A spectrophotometry 

 study of the " end-points " and " fading " of phenolsulfophthalcin indi- 

 cators, O. L. Brightman, J. J. Hopfield, M. R. Meacham, and S. F. Acres 



