434 



SCIENCE 



[N. S. Vol. XXV. No. 637 



Monomolecular glyoxal is prepared by dis- 

 tilling a mixture of commercial glyoxal (4) 

 with phosphorus pentoxide, and cooling the 

 distillate by means of solid carbon dioxide 

 and ether. Care must be taken to avoid the 

 presence of moisture in the apparatus. The 

 compound crystallizes in yellow prisms or 

 spangles, becomes opaque at 10°, melts at 15° 

 and boils at 50°. The vapor is intensely 

 emerald green and condenses to a liquid which 

 is at first green; as this is cooled it becomes 

 yellow and, at very low temperatures, colorless. 

 The vapor has an odor like that of formic 

 aldehyde, but as inhalation continues the 

 smell becomes sweet and not disagreeable. It 

 burns with a violet flame and forms with air 

 a mixture which explodes violently on the ap- 

 plication of a flame. Glyoxal changes spon- 

 taneously into paraglyoxal (3) in a few hours, 

 but on the addition of a little water the trans- 

 formation is instantaneous. If, however, 

 glyoxal be added to a large volume of water 

 it dissolves with a hissing noise and the result- 

 ing liquid, which has a decidedly acid reac- 

 tion, consists of an aqueous solution of mono- 

 molecular glyoxal (1). The glyoxal volatilizes 

 with the steam when the solution is boiled. 

 The solution readily reduces ammoniacal silver 

 nitrate solution, but not Fehling's solution, in 

 which latter respect it resembles the poly- and 

 para-modifications. 



Trimolecular glyoxal (2) is readily pre- 

 pared by treating cinnamic aldehyde, CsH^CH : 

 CHCHO, with ozone. The resulting ozonide, 

 when mixed with water, gives hydrogen per- 

 oxide, benzoic aldehyde (or benzoic acid) and 

 the glyoxal. The reaction may be represented 

 by the formula. 



CeH. CH 



.\i/ 



CHCHO 



O 



the dotted lines showing the positions at 

 which cleavage occurs. 



The intense color of glyoxal is very in- 

 teresting, the simplest diketone, diacetyl, 

 CH3COCOCH3, is also strongly colored, where- 

 as oxalic acid, HOCOOOOH, is absolutely 

 colorless, yet all three substances possess in 



common the grouping OCCO, in one case 



I I 

 united with hydrogen or methyl (colored), in 



the other combined with hydroxyl (colorless). 

 It is tolerably certain that, of the compounds 

 consisting only of the elements carbon, hydro- 

 gen and oxygen, glyoxal is the simplest one to 

 exhibit color. 



J. Bishop Tingle 

 Johns Hopkins Univeesity 



CURRENT NOTES ON METEOROLOGY AND 

 CLIMATOLOGY 



HAIL-SHOOTING — THE QUESTION SETTLED 



It may be remembered that the ' hail-shoot- 

 ing' campaign in Europe was made the sub- 

 ject of a conference held at Graz in 1902. 

 This body concluded that the results up to 

 that time had been negative, and the hope was 

 expressed that the experiments might be con- 

 tinued and carefully watched. The Italian 

 Minister of Agriculture appointed a commis- 

 sion to undertake new experiments, under the 

 presidency of Senator Blaserna. After a 

 study of the results during the period 1902- 

 1906 the conclusion reached by the Commis- 

 sion (Att. dei Lincei, 1906, II. ; Ciel et Terre, 

 January 16, 1907, 591-592) is that the five- 

 year period has yielded an absolutely negative 

 result. The commission reports that there is 

 no hope of preventing damage by hail by 

 means of the so-called ' hail-shooting,' and 

 that protection must be sought along wholly 

 different lines. The question may now be re- 

 garded as definitely settled. 



TROPICAL CYCLONE TRACKS 



We had occasion recently to call attention 

 in these columns to a report by A. Schiick, 

 entitled ' Zur Kenntniss der Wirbelstiirme ' 

 (Hamburg, 1905). A second report on the 

 same subject has since been issued (dated 

 1906), presenting, in elaborate detail, the facts 

 now at hand regarding the tracks of tropical 

 cyclones in the West Indies, the Indian Ocean, 

 and in the Pacific. Dr. Schiick has made 

 search through all available literature, and has 

 plotted the tracks so far as known, on numer- 

 ous charts. In future all students of cyclon- 

 ology will need to refer to Schiick's work. 



