1916] METEOROLOGY. 617 



cated that the amount of sulphur dioxid which actually inhibits jjlcoholic and 

 the various acid fermentations so varies that no exact amount to be used can be 

 prescribed. An investigation on the otfect of sulphur dioxid on wine diseases 

 indicated that the use of sulphur dioxid is a valuable aid in preventing the 

 lactic-acid disease which is so prevalent in certain fruit juices, especially those 

 obtained from overripe pears and apples. On account of the presence of alde- 

 hydes in tlie juices the sulphurous acid soon becomes inactive, so that for 

 reliable results sufficient quantities of potassium metabisulphite should also be 

 added, but because of the continued production of aldehyde during fermentation 

 the quantity of sulphur dioxid and potassium metabisulphite necessary should 

 be largely regulated by the activity of the fermentation. An undue excess is to 

 be avoided at the beginning of the fermentation, as it may injure the bacteria 

 {B. mannitopoevni and B. gracilis), although not the yeasts. 



[Report of the chem.ical section], W. J. Baragiola, C. Godet, and O. Sohuppu 

 (Landw. Jahrb. Schweiz, 29 (1915), No. 5, pp. 568^72).— These pages briefly 

 report the results obtained in the investigations on the diff:erence between acid 

 content and degree of acidity ; analytical investigations on the ripening of 

 grapes and the wine obtained therefrom ; acid reduction in wine in relation to 

 its analysis, physicochemical properties, and hygienic value; the fermentation 

 of grape must under paraffin oil ; and the various combinations of sulphur in 

 wine and their determination. 



METEOROLOGY. 



Weather as a business risk in farming-, W. G. Reed and H. R. Tolley 

 (Geogr. Rev., 2 {1916), No. 1, pp. 48-53, figs. 4; abs. in V. S. Mo. Weather Rev., 

 U {1916), No. 6, pp. 354. 355, figs. .•?).— It is pointed out in this article that 

 the occasional occurrence of unfavorable weather conditions is a risk which 

 must be recognized by successful farmers, and it is stated that in the case of 

 phenomena whose distribution follows the " normal law of frequency " this risk 

 may be determined with a fair degree of accuracy. A method of determining 

 the risk of frost occurrence is described in this paper, and the opinion is 

 expressed that a method of computing the risk from other more complicated 

 phenomena can be worked out. 



" To compute the time available for plant growth in a given proportion of the 

 years the mo.st satisfactory method is that based on the risk at each end of the 

 growing season. If the chance of safety on a given date in spring is one-half 

 and that on a given date in fall is one-half, the chance of safety for the whole 

 period between is one-half multiplied by one-half; that is, one-fourth. For 

 many important crops about a four-fifths chance of safety is essential for con- 

 tinued success. . . . For any place the length of the available growing season 

 (that is, number of days for which the chance is four in five), beginning at the 

 date when the frost risk falls to 10 per cent, is the number of days between 

 this date and the date on v\'hich the chance of fall frost rises to 10 per cent." 



A table is given which simplifies the computation. It is stated that " although 

 this method of determining business risk is subject to limitations because of 

 the shortness of the individual records, a careful examination of the records 

 shows that in the large the computed dates on which the frost risk rises (or 

 falls) to 10 per cent, when compared with the actual number of occurrences, is 

 a very close agreement. From a total of 27,157 observations the lack of agree- 

 ment between the computed and counted cases was but 17 in 10,000." 



Critical period of growth {U. S. Dept. Agr., Nat. Weather and Crop Bid. 

 22 {1916), pp. 2, S. fig. 1). — Attention is called especially to the use of rainfall 

 charts in relation to the critical periods of corn, the most important of which is 

 the ten days following the date of blossoming. 



