743 



In oats the bleaching of the chlorophyll coloring matter was slower and less 

 intensive. As a result of the subsequent diseased condition of the roots, 

 the walls of the vascular bundle elements became a deep brown. 



Soda Dust. 



Ebermayer^ has reported on the injuriousness of sodium fumes. In 

 the manufacture of cellulose, sodium lye, under high pressure, is permitted 

 to act on pulverized pine wood. To get back the sodium, the lye used is 

 vaporized and the residue burned to destroy the organic substances. In 

 this way a considerable amount of sodium carbonate is freed in the air. The 

 leaves of fruit trees near such factories appear brown or black and die after 

 a short time. 



Leaves which had been dipped into a dilute sodium solution (i.oi 

 specific gravity) took on the same color; apple leaves appeared to be some- 

 what less resistant than pears and plums. 



In regard to soda dust, as yet only those cases have been known in 

 which soda from ammonium soda factories was turned to dust by an 

 improper method of ventilating the factory rooms. The soda dissolved by 

 dew, or rain, easily produced in many trees an appearance of the injury from 

 acid vapor, such as the dying of the edges of the leaves, or scattered cor- 

 roded areas. 



In doubtful cases the expert is helped by the condition in wild grasses 

 and especially grain stalks which assume a lemon yellow color. Grain can 

 become sterile according to the time and intensity of the giving ofif of the 

 soda dust and trees may gradually be killed by the repeated annual injury 

 to. their leaves. Besides this, dififerent plant species vary greatly in sensi- 

 tiveness and often are resistant to soda but sensitive to acid smoke, or 

 conversely. My experiments on grain and wild grasses (Agropyrum 

 re pens, Agrostis vulgaris, Lolium, etc.), in which I covered them with dust 

 while wet with dew, gave the same yellow discoloration, even in the glumes, 

 just as in natural injuries- which were demonstrable at a distance of 2 kilo- 

 meters from the factory. Konig^ observed that the edges of barley leaves 

 became white. Red clover is said at first to show small black spots on the 

 leaves, some of which later become entirely black and drop ofif. The same 

 is true of potatoes. Konig found perforations near the brown edges of the 

 leaves in oaks as in cherries. The needles of the white fir are said to 

 become yellow at the tip and fall oil. As a result of his analyses, Konig 

 considers the action of the soda to lie not only in a humification of the leaf 

 substances, but also in the taking up of soda by the leaves, from which it 

 wanders down to the roots. An increase in acids, especially silicic and 

 sulfuric acids, takes place at the same time with the increase of the amounts 



1 Ein Beitrag zur Patholog-ie der Obstbaume. Tag-ebl. d. Naturf. — Vers, zu 

 Hamburg, cit. Biedermann's Centralbl. 1S77, II, p. 318. 



2 Zeitsch. f. Pflanzenkrankh. 1892, p. 154, note. 



3 Borner, Haselhoff and Konig. tJber die Schadlichlteit von Sodastaub und 

 Ammoniakgarf auf die Vegetation. Mitgeteilt von Konig, Landwirtscli. .Jahrb. XXI, 

 cit. Zeitscli. f. Pflanzenkrankh. 1893, p. 98. 



