586 RECORD OF MEETINGS OF THE 



b (a + m) = (b + m) a, 

 b = a, 

 and hence 



A& = Aa. 

 That is, the divisions of the scale on the Piezic barometer are 

 of the same size as those on the ordinary barometer. How- 

 ever, in practice the upper bulb always contains some mercury 

 after the air is entrapped. The general effect of this is to make 

 Aa < A6. 



Dr. Kunz described the object of and the success of the radium 

 exhibit, stating that many of the most eminent investigators, in- 

 cluding Sir William Crookes and Professor Rutherford, had sent 

 their original material. The collection was shown in an upper 

 hall of the museum. There was also exhibited the Kunz 108 1- 

 pound mass of Canon Diablo meteoric iron, the largest mass 

 known of this meteoric iron. Dr. Kunz stated that Professor 

 Henri Moissan of Paris had discovered, in dissolving 183 pounds 

 of this material (Canon Diablo meteorite), not only crystalline 

 diamonds, but the crystalline substance carbon silicide, never 

 before discovered as a natural product, but extensively manu- 

 factured and used in the arts under the name of carborundum. 

 In view of the many eminent discoveries of Professor Moissan 

 in the field of chemistry and electro-metallurgy, as well as in 

 the study of meteorites and of diamond formation, Dr. Kunz 

 suggested that this mineral be named moissanite in his honor. 



Dr. Cole in his paper said that the immediate discharge 

 from an X-ray tube consists of two distinct classes of so-called 

 rays- — direct and indirect. The direct rays have their inception 

 at the focal point of the anode and radiate in direct lines and 

 are not reflected or deflected and do not set up secondary rays, 

 but are absorbed by the tissue of the body in proportion to the 

 amounts of solid contained therein. 



The indirect rays radiate from the walls of the tube and are 

 projected at various angles, causing secondary rays in objects 

 with which they come in contact, especially the soft tissue, 

 and give great penetration. The effect attained depends on the 

 amount of current, frequency of interruption, and molecular 

 action of glass. 



