May 1, 1896 ] 



SCIENCE. 



677 



Prof. C. H. Smyth, Jr., on ' The Origin of the 

 Talc Deposits near Gouverneur, N. Y.' Dr. 

 Smyth first described the geological surround- 

 ings of the talc and showed that it occurs along 

 a series of belts in limestone walls and that the 

 previously published statement that it occurs 

 in gneiss is incorrect. By means of microscopic 

 sections he traced its development by the alter- 

 ation of tremolite in largest part and from en- 

 statite to a less degree, the changes in both 

 having been affected through the agency of 

 water and carbonic acid. The talc occurs in 

 two forms — a scaly variety, or talc proper, and 

 a fibrous variety or agalite. He was unable to 

 determine whether the original rock was a 

 hasic intrusive or a siliceous magnesian lime- 

 stone. The full paper will appear in the 

 School of Mines Quarterly for July, 1896. 



The third paper of the evening was by Prof. 

 H. P. Gushing, and was entitled ' Are there 

 Pre-Cambrian and Post-Ordovician Trap Dykes 

 in the Adirondacks.' Field work in Clinton 

 county, N. Y., had convinced the writer that 

 there were two periods of dyke intrusion in the 

 Adirondacks. The first yielded the porphyries 

 or bostonite, the Camptonites and non-feld- 

 spathic dykes, which cut the Paleozoic strata 

 up to and through the Utica slate. These 

 dykes, are chiefly limited to the shores of Lake 

 Champlain, both in New York and Vermont. 

 They practically lack diabase. The second set 

 are limited to archean rocks, are much more 

 numerous and are practically all diabase. One 

 hundred and sixteen dykes in all are known 

 in Clinton county ; sixteen belong to the 

 first series, while the remaining one hundred 

 belong to the second. The latter have been 

 found in the gneisses in many cases very near 

 the contacts with the Potsdam sandstone, but 

 in no case have they been found penetrating the 

 sandstone. The same relations have been 

 noted by Smyth at the Thousand Islands. 



Prof Gushing therefore urged that these 

 dykes should be considered a separate series of 

 rocks that had been formed subsequently to the 

 metamorphism of the crystalline rock and be- 

 fore the deposition of the Potsdam sandstone. 

 The paper will appear in full in the Transac- 

 tions. J. F. Kemp, 



Secretary. 



BIOLOGICAL SOCIETY OF WASHINGTON, 259TH 

 MEETING, SATURDAY', APRIL 4. 



The first paper of the evening was Pfaff's 

 Recent Investigations on Rhus Poisoning, and 

 was presented by V. K. Ghesnut. The writer 

 briefly analyzed the work of preceding inves- 

 tigators and showed how the different ideas 

 regarding the volatile nature of the poison 

 were influenced by successive stages in the de- 

 velopment of the science of Organic Chemistry 

 and it was shown that nothing but an oil, like 

 Toxicodendral, could produce the effects of 

 poison ivy. Experiments and authentic cases 

 of poisoning were described to corroborate 

 PfafF's statements that ; 



1. While water will not remove the oil from 

 the skin an hour after contact, alcohol will do 

 so very readily, especially when added in suc- 

 cessive portions. 



2. The poison is readily communicated to 

 different parts of the body and to other persons 

 by contact and friction. 



3. The wood, as well as the leaves, is poison- 

 ous and the active principle is present in the 

 plant at all times of the year. 



4. Herbarium specimens may produce the 

 poisonous effects. 



The effect of alcohol as a palliative, and of an 

 alcoholic solution of lead acetate as an antidote 

 was shown by experiments made by the writer 

 upon himself. 



B. T. Galloway spoke of the Action of Copper 

 in Poisoning Fungi, stating that although copper 

 in various forms had been used for years as a 

 fungicide, little was known in regard to the 

 exact nature of its toxic action on plants. Most 

 of the studies made within the past 8 or 10 

 years had for their object the determination of 

 the amount of copper necessary to kill the 

 spores of various fungi. In this connection the 

 investigations of Nageli, and the oligodynamic 

 phenomena described by him, were reviewed. 

 Finally the possible methods by means of which 

 spores of fungi may be killed or prevented from 

 infecting living plants, were discussed and at- 

 tention was called to a paper on the subject by 

 Mr. W. T. Swingle, of the Department of Agri- 

 culture, soon to be published. 



Under the title of the Story of two Salmon 



