10 INJURY TO VEGETATION BY SMELTEE FUMES. 



EXPERIMENTAL WORK. 



VISIBLE INJURY TO VEGETATION BY SULPHUR DIOXID. 

 COMPILED DATA. 



First, it must be ascertained whether sulphur dioxid does injure 

 vegetation, how small a quantity may be injurious, and through 

 what organs of the plant such injury takes place. Light is thrown 

 on these points by the work of several foreign chemists. M. Freytag" 

 showed conclusively by experimental work that the sulphur dioxid 

 and trioxid in the air does not injure the plant through the medium 

 of the roots. For this purpose he watered vigorous wheat, oat, and 

 pea plants night and morning with 20 liters of water, containing in 

 one case 4 grams of sulphurous acid and in the other case 5 grams of 

 sulphuric acid. This continued for forty-five days. At the end of 

 this time the amounts of acid were raised to 6 grams of sulphurous 

 and 7.5 grams of sulphuric acid for fifteen days. Then for fifteen 

 days the amounts of acid were increased to 8 grams of sulphurous 

 and 10 grams of sulphuric. At the end of this time no injury to the 

 plants could be noted, and the yield of crop was as great in the case 

 of the plants treated with acid as in the case of untreated plants. 



J. von Schroeder and W. Schmitz Dumont, 6 by an investigation 

 made in 1896, showed that the injury to vegetation by sulphur dioxid 

 is not by means of the roots, but through the leaves, and that even 

 extremely minute quantities of sulphur dipxid are injurious. They 

 used pines, and conducted the experiment in the following manner: 



(a) Part standing above the earth only treated with sulphur dioxid. 



(b) Part standing above the earth and earth in which plant was 

 grown treated with same strength of sulphur dioxid. 



(c) The same amount of sulphur dioxid, in water solution, as used 

 in (a) and (b) added to the earth around the roots. 



(d) Control plant not treated. 



On the first day a concentrate of 1:20,000 parts of sulphur dioxid 

 was used, on the second 1:10,000, on the third, fourth, and fifth, 

 1 : 5,000. Without going into the details of the experiment, it will 

 suffice to say that this treatment seriously injured (a); injured (6), 

 but not to so great an extent as (a), and did not injure (c) in any way. 

 The control plant was in good condition at the end of the experiment. 



Further work showed that upon fumigating pines for 109 times with 

 I part of sulphur dioxid to 100,000 parts of air great injury was 

 inflicted. A large number of the needles turned brown or yellow, and 

 practically all became partly yellow. Upon fumigating 9 pines for 

 583 times with 1 part of sulphur dioxid to 1,000,000 parts of air injury 

 was also noted. Other chemists and biologists have worked upon 

 this same subject, among them being A. Stoekhardt, c A. Wieler, d 



"Mitt. d. konigl. landw. Akad., Poppelsdorf. 1869, 2. 



^Tharander forstl. Jahrb., 1896, 46: 1. 



<"Tharander forstl. Jahrb., 1871, 21: 230. rf Ber. d. botan. Ges., 1902, JO: 556. 



