1913] LIPMAN & WILSON—TOXIC SALTS AND ACIDS 411 
dry weight of the soil, and while the soils free from copper gave 
much larger yields of fruit and vine than did those grown in soils 
containing copper, it is amazing to note such extreme resistance 
to large quantities of a poisonous compound on the part of plants 
as manifested by more or less growth. The author of the paper 
gives the results only as preliminary and promises a much more 
thorough review of the investigations later. Twenty years have 
passed since, however, and we are unable to find any further pub- 
lished data from the New York Experiment Station on that subject. 
One more note in the paper is of interest, and that is of a con- 
temporary paper by Hasetuorr,® the conclusions of which are 
quoted, in which that author states among other things that soluble 
copper salts are injurious to plants, and that while concentrations 
up to 5 ppm. are harmless, the presence of 10 ppm. of copper in 
soil has a marked retarding action. In the Iowa bulletin by Pam- 
MEL we find that copper solutions had a marked retarding effect on 
the root development of plants, and that no roots at all developed 
where the concentration of copper was large. It is unfortunate 
that PaAmMMEL does not make mention of the concentrations of 
copper existing in the various experimental plots in the greenhouse. 
So far as the effect of zinc salts on plant growth is concerned, 
there is but meager information. We have, however, the recent 
investigations in Germany on the effect of the zinc in galvanized 
iron cylinders, used for vegetation experiments, on plant growth. 
From these it would appear that zinc may be distinctly toxic to 
plant growth. 
agg cee 5 with manganese, however, have been very numer- 
; but their results have been so conflicting as to make more 
ia work very desirable. The reader is referred for a 
more complete bibliography on the effects of manganese in soils 
on plant growth to a recent publication by W. P. KELLEY.’ 
Along with the problems of smelter fumes and smelter wastes, 
has come the idea of the condensation of the sulphur dioxide and 
the manufacture of H,SO,. It has been calculated by Corrrett and 
others, however, who have made a careful study of the problems, 
° Landw. Jahrb. 21: 263. 
? Hawaii Exp. Sta. Bull. 26. 
