478 



SCIENCE 



[N. S. Vol. XXVI. No. 667 



results obtained by using tbe solid emanations 

 on plants, we can at least say, " not proven." 



On pages 962, 963, 964, 965, 966 and 967, are 

 given tables showing: (1) the chemical com- 

 position of the flue dust; (2) the lead, copper 

 and arsenic content of hay around a smelter; 



(3) the lead, copper and arsenic content of the 

 dust from rafters in barns around the smelter ; 



(4) the action of mixtures of flue dust and soil 

 on sugar beets ; (5) the action of aqueous solu- 

 tion of flue dust on sugar beets. 



His results on the composition of the 

 samples of hay around the smelter and the 

 composition of the dust from rafters in bams, 

 etc., are of only limited value since he does 

 not give the distances from the smelter at 

 which each of these samples was taken. His 

 results on the effect of the mixture of flue dust 

 and soil, as well as his results with the water 

 solution on sugar beets, are practically value- 

 less, since the actual amount of flue dust 

 added to the leaves and its relative weight as 

 compared with the leaves are not given. In 

 other words, it is impossible from the data 

 given to judge how much of the flue dust (in- 

 cluding arsenic, copper, etc.) was added to 

 each leaf. Without the above data it is im- 

 possible to tell whether the amount of lead, 

 copper and arsenic added by dusting or spray- 

 ing corresponds to the amount of these sub- 

 stances actually found in the hay around the 

 smelter, or not. Here ag'ain the experiments 

 are incomplete and here again one may say, 

 " not proven." 



On the whole, then, it is at once evident that 

 the series of experiments carried out by Pro- 

 fessor Ebaugh do show that the solid emana- 

 tions from a smelter in certain strengths are 

 extremely toxic to plants. They do not show, 

 however, that such solid emanations are in- 

 jurious when added in the strengths which may 

 settle on the leaves around a smelter. 



Again, all the fumigation experiments 

 with sulphur dioxide, carried out in the above 

 article, except one, show that the leaves were 

 injured and many of the experiments (such as 

 they were) on treating plants with the diluted 

 solid emanations show injury, yet with the 

 proofs as evenly balanced as they are, the 



author of the article claims that " we are 

 forced by the weight of evidence to the con- 

 clusion stated in the introduction, viz, that 

 heretofore undue emphasis has been laid upon 

 the injurious effect of sulphur dioxide upon 

 growing plants, and that the harmful action 

 of the solid emanations from the smelters — 

 the so-called flue dust — has been seriously 

 underestimated." 



Finally, the writer would draw attention 

 to the country in the vicinity of Ducktown, 

 Tenn. Here, well-marked injury to forests 

 can be noted at a distance of about twenty- 

 five miles from the smelter, yet solid emana- 

 tions which might have any injurious effect 

 on foliage consist almost entirely of copper 

 compounds since arsenic is not present in 

 appreciable amounts, if at all. It is well 

 known that grape foliage, apple foliage and 

 foliage of certain . other plants can be treated 

 with about 1 part of copper sulphate, to 400 

 to 500 parts of water, without injury. It 

 is hardly possible to believe that the copper 

 compound from the smelter could be carried 

 in more than a trace (if even to this extent) 

 for a distance of twenty-five miles. It is less 

 possible to believe that they could be carried 

 in such quantities as to amount to 1/400 of 

 the rain that might fall upon them, yet here 

 we have a case of decided injury at a distance 

 of twenty-five miles. Add to the above rea- 

 soning the fact that the sulphur trioxide con- 

 tent of the injured foliage can be shown to be 

 greater than that of the uninjured foliage 

 beyond the range of damage and that the 

 leaves of the trees have the nearly character- 

 istic appearance of sulphur dioxide injury, 

 and it is impossible to reach any conclusion 

 except that the trees were injured by sulphur 

 dioxide. 



While it is possible, in fact extremely prob- 

 able, that in actual practise solid emanations 

 in the vicinity of a smelter do injure vegeta- 

 tion to a greater or less extent, this fact has 

 not been proven by the above experiments. 



J. K. Haywood 

 Bureau of Chemistet, 

 U. S. Department of Agriculture 



