512 EXPERIMENT STATION RECORD. [Vol.37 



The natural accelerator of Para rubber, H. P. Ste\-ens {Jour. Soc. Chem. 

 Indus., 36 (1917), No. 7, pp. 365-370). — Experimental data are submitted which 

 show " that the rapid curing property of matured coagulura is due to organic 

 nitrogenous bases formed during putrefaction, as small quantities of these bases 

 can be extracted from the rapidly curing rubber which has undergone putrefac- 

 tion while only a trace can be extracted from the ordinary pale crepe." Similar 

 bases were extracted from the residual liquors. Very small amounts of these 

 bases were found to exert a marked effect in promoting vulcanization. 



METEOROLOGY. 



Hail in the United States, A. J. Henry (U. S. Mo. Weather Rev., 45 (1917), 

 No. 3, pp. 9Jf-99, pis. 5). — This article reviews geogi-aphic, seasonal, and general 

 distribution of hail in the United States and discusses theories of hail. It is 

 based upon 1G7 records covering an area of 3,026.789 square miles. 



" The region of most frequent occurrence, four or more storms per year, is in 

 southeastern Wyoming and eastward therefrom, including the western portions 

 of Kansas, Nebraska, and Oklahoma. Adjoining this region of maximum 

 frequency, especially to the eastward, the average number of storms per annum 

 decreases to three. . . . 



" Hail in the United States is, in general, a phenomenon of the warm season, 

 the only notable exception being along the immediate Pacific coast from San 

 Francisco northward. On that strip of coast hail occurs chiefly from November 

 to March, a season that is substantially the same as that of the rains in that 

 part of the United States. . . . Practically no damage to agricultural crops by 

 hail is possible in the Pacific Coast States and only small damage is possible 

 in the Gulf States both by reason of the infrequency of the phenomenon and 

 the absence of crops at the time of greatest frequency. In Kansas, Nebraska, 

 South Dakota, western Iowa, and northwestern Missouri hail falls at a time 

 when destruction of crops is possible." 



Reviewing the data for hail distribution in Europe, as well as in the United 

 States, the conclusion is reached that " hailstorms over both land and water 

 occur most frequently in temperate latitudes, the belt of greatest frequency 

 being between the thirty-fifth and the sixtieth parallels in both hemispheres. 

 They are infrequent in the Tropics, especially over the lowlands. In Arctic 

 and Antarctic regions, while hail occurs more frequently than was once sup- 

 posed, lack of precise observations make it somewhat conjectural whether the 

 hail reported is graupel or true hail." 



It is stated that in the United States the region of greatest thunderstorm 

 frequency does not coincide with the region of greatest hail activity, and 

 although hail is generally associated with tornadoes the author doubts whether 

 the fundamental conditions for the formation of a tornado are always present 

 in a hailstorm. 



Observations on the possible influence of violent cannonading on rainfall, 

 Sebkrt [Compt. Rend. Acad. Sri. [Pans], 16k {1917), No. 19. pp. 70S. 70^).— 

 Supplementing a previous note (E. S. R., 37, p. 418) the author calls attention to 

 a series of observations which have been made at the Central Meteorological 

 Bureau at Paris which may be useful in the study of this subject. 



Lightning and forest fires in California, A. H. Palmer {U. S. Mo. Weather 

 Rev., 45 {1917), No. 3, pp. 99-102, pis. 3, fig. l).—lt is shown in this article that 

 lightning is an important cause of forest fires, and the development of the fire- 

 weather warning .service, as well as the making available of facilities to subdue 

 forest fires, is urged. 



