32 EXPERIMENT STATION RECORD. 



plant growth, also that in the crop an increase of sodium and of sulphuric acid 

 con-esponded to an increase of sodium sulphate in the soil or the nutritive 

 solution employed. 



The distribution of atmospheric impurities in the neighborhood of an 

 industrial city, C. Crowthee and D. W. Steuart {Jour. Agr. 8ci. [England], 

 5 {1913), No. 4, pp. 391-408, figs. 2). — In continuation of a previous report 

 (E. S. R., 25, p. 434) an account is given of an examination of the atmosphere 

 in the counti-y surrounding the city to a distance of about 7 miles. 



The observations here reported show that no general effect upon the opening 

 of the buds could be detected. By the end of May smoke damage began to be 

 evident within 2 miles of the center of the city by the appearance on the 

 leaves of sycamores and limes of characteristic brown blotches. During June 

 the conditions, so far as the leaves were concerned, became consideraljly worse, 

 and in the case of many trees, as shown by the examination of cross sections, 

 there was very little annual growth. Criticisms having been made of previous 

 observations relating to the clogging of the stomata, microscopical examina- 

 tions were made of a number of evergreen leaves which confirmed in the main 

 the previous statements. 



Summarizing the results observed, the authors state that the sulphur content 

 of the rain falling at a given station affords a fairly reliable diagnosis of the 

 degree of pollution of the atmosphere by smoke providing the observations be 

 prolonged over several months. The rain analyses show further that appre- 

 ciable smoke pollution remains throughout the agricultural area at distances 

 of 7 miles from the city, the rate of improvement being slower in the direction 

 of the prevailing winds than in other directions. 



The influence of tar, particularly that of tarred streets, upon vegetation, 

 P. Claussen (Ar&. K. Biol. Anst. Land. u. Forstio., 8 {1913), No. 5, pp. 493- 

 514, pis. 2, figs. 8). — As the result of experimentation with 5 ornamental 

 flowering herbs, 2 firs, and a spruce, exposed to fumes of several commercial 

 tars in air or soil, the author states that the various kinds of tar sold for 

 highway building purposes differ widely as to effect on the plants; that the 

 injurious effects of tar vapors are closely related to their concentration, this 

 depending upon volatility and temperature; and that species of plants differ 

 widely as to their sensitivity to such vapors. 



It is recommended that the plants be placed at a safe distance from the 

 tarred surfaces; that careful tests be made of tars intended for such pur- 

 poses; that the practice of heating the tar in the neighborhood of the plants 

 be avoided, also that as low temperatures as are practical be employed ; and that 

 this work be done so far as possible when the foliage is off" the trees, and by 

 no means during the very early stages of its formation. 



FIELD CROPS. 



study of farm practice versus field experiments, W. J. Spuxman {Proc. 

 8oc. Prom. Agr. Set., 33 {1912), pp. 103-113, figs. 3). — This article has been 

 previously noted (E. S. R., 28, p. 198). 



Determination of probable error in field experiments, Harnoth {Mitt. 

 Deut. Landw. GeselL, 28 {1913), Nos. 5, pp. 70-73, fig. 1; 6, pp. 87-90; 7, pp. 

 105-107). — This paper includes discussions of methods of reckoning the varia- 

 tion of each check plat of a series from the mean of their yields. For this 



purpose Gauss' formula, R=± -f=^LU. is used, in which Ivl is the sum of the 



■\i n[n — l] 



variations regardless of signs, n the number of observations, and 0.845 is a 



