472 



SCIENCE. 



FN. S. Vol. VIII. No. 197. 



property according to forestry principles. 

 Forest Commissioner Fox, of New York, 

 reported on the acquisition of Adirondack 

 lands by the State to the extent of one and 

 a-half million dollars. On Tuesday after- 

 noon the Association, in a bodj', drove 

 through the Middlesex Fells, and the dis- 

 cussions in the evening, after a dinner at 

 the hotel situated in the forest park, turned 

 naturally on the application of silviculture 

 to such parks. It appeared that the Metro- 

 politan Park Commission had not yet 

 formulated plans as to the management of 

 the woodlands. Dr. Schenck, of Baltimore, 

 and Mr. Olmstead, of the well-known firm 

 of landscape architects, advocated sound 

 measures for the replacing of the worth- 

 less coppice growth, which is bound to de- 

 teriorate, by a healthy seedling growth. 



An important feature of the meeting 

 was the discussion of the aims and ob- 

 jects of the newly established State Col- 

 lege of Forestry at Cornell, by its Director, 

 Dr. B. E. Fernow. This address will be 

 printed in full in Science. In the discus- 

 sion Professor Lazenby referred to a move- 

 ment in similar direction which was shaping 

 itself in Ohio. Among the usual resolutions 

 which it is the custom to pass at these 

 meetings the most important was one call- 

 ing upon the federal government to place its 

 forest reserves under technical non-political 

 management. 



The Association adjourned to hold an- 

 other summer meeting at Omaha, in connec- 

 tion with the Trans-Mississippi and Inter- 

 national Exposition. 



NOTES ON PHYSICS. 

 GAY LUSSAO'S LAW AND ATMOSPHEKIC NITRO- 

 GEN. 



A VERY curious deviation of atmospheric 

 air from the Laws of Gay Lussac and Boyle 

 has been studied by H. Teudt (Zeit. fiir 

 Phys. Chem., XXVI., p. 113). When first 



heated, the expansion above 350° is exces- 

 sive. The deviation from Gay Lussac's 

 Law being 2 per cent, at 400° and 3 per 

 cent, at 450°. This anomalous expansion 

 is exhibited by atmospheric nitrogen alone, 

 but not by oxygen, carbon dioxide, chemi- 

 cally prepared nitrogen, by air which has 

 been previously heated, nor by air collected 

 after a rain. Teudt suggests, in explana- 

 tion, the existence of an allotropic form of 

 nitrogen and pointe out that the close re- 

 lationship between nitrogen and phosphorus 

 supports this view ; the allotropic form of 

 nitrogen being changed to the ordinary 

 form at high temperatures. Holborn and 

 Wien, in connection with their work on the 

 air thermometer, have pointed out that air 

 at the first heating does not conform to Gay 

 Lussac's Law. 



LIQUID AMMONIA. 



E. C. Franklin (Paper read before Sec- 

 tion C at Boston) has made an elaborate 

 study of liquid ammonia, which has been 

 known for some time to approach water in 

 its properties as a solvent. He finds its 

 heat of vaporization to be about 330, while 

 the calculated value is 358 by Trouton's 

 formula, 321 by the formula of Wood, and 

 330 by the formula of Peabody. He finds 

 the constant of molecular elevation of the 

 boiling point of liquid ammonia to be 3.4, 

 which is lower than for any other known 

 substance. He has measured the electrical 

 conductivity of various substances dissolved 

 in liquid ammonia, and he finds the con- 

 ductivity to increase with temperature, 

 reach a maximum and then decrease, be- 

 coming zero at the critical temperature of 

 liquid ammonia. 



H. M. Goodwin (Paper read before Sec- 

 tion B at Boston) has determined the 

 dielectric constant of liquid ammonia and 

 finds it larger, indeed, than the dielectric 

 constants of alcohol, ether and the like, but 

 not so nearly equal to that of water as was 



