abstracts: forestry 635 



but they show that metalhc bases are incapal)le of removing sihca 

 from solution completely. The work of Anthon and Schiirmann, 

 which covered the sulfides fairly completely, is discussed in order to 

 compare their results with the solubilities and solubility products 

 determined by physicochemical methods. The order of solubility of 

 sulfides obtained from experiments on fractional precipitation agrees 

 better with solubilit}' products calculated from electromotive force 

 measurements than it does with Weigel's results obtained by conduc- 

 tivity determinations. Incidentally, it is shown that the immediate 

 precipitate produced by alkaline- sulfides and copper salts contains 

 a much higher proportion of cuprous sulfide than that formed by 

 hydrogen sulfide in acid solutions. The precipitation series obtained 

 for the hydroxides, beginning with the most insoluble, is as follows: 

 Ferric, aluminium, cupric, zinc, lead, nickel, silver, ferrous, manganous, 

 magnesium, calcium. The series obtained for carbonates, based on 

 results with sodium bicarbonate as precipitant, is: Mercury, lead, 

 cadmium, manganese, silver, ferrous, zinc, calcium, magnesium. 



R. C. W. 



FORESTRY.— Fa?i/e of the big tree contest. W. H. Lamb. The Jour- 

 nal of Heredity, 6: 424-428. 1915. 

 This is a discussion of the scientific value of the prize photograph 

 contest conducted by the American Genetic Association, in which the 

 largest hardwood tree discovered was a sycamore {Platanus occidentalis) , 

 located at Worth ington, Indiana, which measures 42 feet 3 inches in 

 circumference and about 140 feet in height. In this contest the in- 

 terest of the forester and the dendrologist centered upon the ascertain- 

 ment of the species reaching the maximum size, the greatest size at- 

 tained by every species, and upon consideration of the geographic loca- 

 tion of notable trees with respect to their natural range. In discussing 

 the contest from' this viewpoint, data are presented upon the influence 

 of heredit}^ and environment upon the form and size of trees, on the 

 doctrine of indefinite longevity in trees, and on the scientific and aes- 

 thetic value of large specimens. Maps are included showing the natu- 

 ral range and location of the largest individ'uals of six important timber 

 trees, and attention is called to the deske of the Association for informa- 

 tion on the location, life history, and size of notable trees throughout 

 the United States. ' W. H. L. 



