28 



SCIENCE 



[N. S. Vol. XXXIV. No. 862 



watt tungsten lamp was the largest available 

 giving the required ratio). This ratio was 

 computed from a consideration of the wave- 

 lengths transmitted by the blue glass used, 

 namely, about 710 and 420 fjLjj., and of the in- 

 dices of refraction of carbon disulphide for 

 these wave-lengths. This part of the bulb was 

 cut out, forming a sort of shallow bowl into 

 which a quantity of carbon disulphide was 

 poured. I thus had an astigmatic plano-con- 

 vex lens which gave as an image a minute 

 red-and-blue cross when purple light was 

 passed vertically through it. Later the frag- 

 ment of the bulb was cemented with shellac on 

 to a flat piece of glass, forming a cell into 

 which the carbon disulphide could be intro- 

 duced. A diagram was used to screen off all 

 but a small portion of the lens. 



In a rudimentary way the appearance can 

 be projected on to a screen by passing light 

 obliquely through a common plano-convex 

 lens.' 



W. G. Cady 



Wesleyan University 



THE IOWA ACADEMY OF SCIENCE 



The sessions of the academy were held in Car- 

 negie Science Hall, Coe College, Cedar Rapids, 

 April 28 and 29. 



The public address by Dr. Edward L. Nichols, 

 of Cornell University, on ' ' The Ends of the Spec- 

 trum — the Infra-red and the Ultra-violet," was 

 given on Eriday at 8:00 P.M. 



Sessions of the academy for the reading of 

 papers were open to the public. 

 Nitrogen in Rain and Snow: Nicholas Knight. 



Seventeen samples of rain and snow were col- 

 lected on the college campus at Mt. Vernon, Iowa, 

 during nine months of the year 1909-1910. The 

 nitrogen in the free and albuminoid ammonia and 

 in the nitrates and nitrites was determined. Com- 

 parisons were made of the relative amounts of 

 nitrogen precipitated with the rain and snow. 

 According to the experiments, each acre would 

 receive in the nine months between thirteen and 

 fourteen pounds of nitrogen from the rains and 

 snows. 



Perchloric Acid in Electro-chemical Analysis: W. 



S. Hendrixson. 



'I am indebted to Professor Raymond Dodge 

 for this suggestion. 



Asteroid, 1909, JA: Seth Nicholson and Alma 



Stots. 

 Vaccination against Typhoid Fever: Henry 



Albert. 



The writer briefly reviewed the experimental 

 work on immunization with cultures of typhoid 

 bacilli, then gave the technique and preparation 

 of vaccine as generally employed at present for 

 the preventive vaccination against typhoid fever. 

 The reaction was divided into a local one which 

 disappears in the course of a few days and a 

 general one which he divided into leucocytic, 

 phagocytic, agglutinitic and bacteriolytic. There 

 is an increase in the number of leucocytes, the 

 power of phagocytosis, and of the agglutinins and 

 bacteriolysins in the blood serum. The presence 

 of immune bodies may be demonstrated as long 

 as one year after vaccination and is of both a 

 higher degree and of longer duration than usually 

 occurs following an attack of typhoid fever. 

 Reasoning from analogy from the protection af- 

 forded by one attack of the disease, he believes 

 that the immunity conferred by vaccination exerts 

 more or less protective influence throughout the 

 life of an individual. He would extend anti- 

 typhoid vaccination to all liable to exposure to 

 infection with typhoid fever. 



Flowers of Story County: J. M. Lindley. 



The Succession of Floras on the Sand Dunes of 



Iowa: B. Shimek. 



A discussion of the changes of the earliest flora 

 of these dunes, consisting largely of leguminose 

 plants, to the typical prairie flora of the older 

 areas. 

 The NebrasTcan Drift: B. Shimek. 



A discussion of its distribution and correlation, 

 including the results of recent investigations. The 

 conclusion is reached that this drift can not be 

 correlated with the Jerseyan and Albertan, and 

 that the name ' ' Kansan ' ' should not be trans- 

 ferred to it. 



Notes on Fungus Diseases: L. H. Pammel. 



Gives a record of a very destructive Exoascus 

 upon the hard maple in the Eocky Mountains, also 

 an account of the destructive Exoascus on the oak, 

 the destructive Fames iginarius on the quaking 

 aspen in some parts of the Wasatch Mountains in 

 Utah, as well as the destructive work of Pleurotus 

 upon the box elder and other deciduous trees in 

 Iowa. 



An Abnormal Carpel in Stenospermatium : J. E. 

 Gow. 



