19201 METEOROLOGY. 717 



iucludiiif; the necessary equipment, varieties of {grapes, and the different proc- 

 esses involved. Diaj^ranis are included of diflcrent tyi>es of vacuum pans witli 

 dry and wet vacuum-pump connections. 



The s<'cond method, whicii is described itriclly, is an application of the 

 process developed by (Jore (E. S. K., 3."i, p. .SltJ). This consists essentially of 

 freezing the fresh juice and separating tlie sirup from the ice by centrifugal 

 force. As the sirup obtained from grape juice by tliis process is not sweet 

 enough for general use, it has been found necessary to blend with it a sirup 

 of 7U to 75° Balling made in an ordinary vacuum pan. The resulting .siruj) is 

 said to retain more of (he fresh grape llavor than a sirujt made entirely by Ihc 

 vacuum process. 



It is suggested that grape sirup manufacture can be undertaken profitably 

 by large wineries, milk canneries, and breweries. Attention is called to the 

 inii)ortance of tlie character of tlie lining of the vacuum pans. As analyses 

 have sliown that small amounts of copper may he dissohtnl in tlie juice during 

 concentration, it is considered advisable to use monel metal or glass-lined 

 vacuum pans. 



rnferniented fruit juices, W. V. Crukss {California Sta. C'irc. 220 {li>20), 

 pp. 32, fiys. JS). — This circular consists of a compilation of informaticjn from 

 various sources on the home and connnercial manufacture of unfermentcd fruit 

 juices. The general i)rinciples involved are discussed briefly and the most 

 common forms of e<iiiipment for fruit-juice manufacture are describetl and 

 illustrated by photographs and diagrams, including a diagram of a home- 

 made fruit-juice press, which is also suitable for pressing olives for oil. 



The manufacture of grape juice is described in detail, and estimates are given 

 of costs and returns on graiK? juice based upon the results of experiments at 

 the university farm. Brief directions are also given for the manufacture of 

 unfennented apple, loganberry, pomegranate, and citrus fruit juices. 



Tar-still operation in Iiardwood distillation plants, I.. F. Hawley and 

 H. N. Calukuwood, .ik. {./our. I)}dii.<s. and Engin. Chein., U {1020), Xo. 7, pp. 68-'/, 

 685). 



METEOROLOGY. 



Relation between the annual precipitation and tlie number of head of 

 stock grazed per square mile, J. W. S-MITH {U. »S'. Mo. Weather Rev., JfS 

 {VJ20), Au. 6, pp. 311-317; abs. in Bui. Amer. Met. Sac, 1 {1920), No. 5, p. 55). — 

 A review of the available data indicates that wherever grazing is carried on 

 throughout the year it is possible to establish a close ratio between annual 

 rainfall and the number of head of stock that can be grazed per square mile. 

 " In New South Wales, for example, where the rainfall is between 20 and 30 in., 

 250 sheep are grazed to the square mile ; where it is between 10 and 20 in., 

 100 sheep; and where under 10 in., only 40 sli(>ep to the square mile." 



" In the Great Plains States the relation between the annual precipitation 

 and the number of head of stock that can be grazed i)er square mile can be 

 fairly well established, the possible number decreasing with fair uniformity 

 from east to west with the decreasing annual rainfall. The number grazed 

 in Oklahoma and Texas is close to 50 per square mile where the rainfall is 

 between 25 and 35 in. and about 40 where the rainfall is frcun 15 to 25 in. 



"'In the fireat IMaitis States north of Oklahoma, where feeding is necessary 

 during the wintertime and where the rate of evaporation is less in the summer 

 months, the grazing rate averages close to 20 where the rainfal! is between Ht 

 and 15 in., nearly 40 where it is from 15 to 20 in., and nearly 80 where it is 

 20 to 25 in. The ratio rises at a faster rate with heavier rainfall. 



