388 Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistky and Physics. 



1. The Preparation and Properties of Tantalum. — Metallic 

 tantalum has been prepared by Berzelius, Rose, and more recently 

 by Moissan, but always in an impure condition, either as a black 

 powder, or, in Moissan's case, as a very hard, brittle substance 

 containing carbon. Werner von Bolton has recently suc- 

 ceeded in obtaining tantalum in a practically pure condition, and 

 finds that it possesses some very remarkable properties which 

 promise to make the metal one of great practical importance. 

 Von Bolton has improved the processes of Berzelius and Rose 

 (where a double fluoride is reduced with an alkali metal) and he 

 has purified the product further by fusing it in a vacuum by 

 means of the electric arc. He has also applied an interesting 

 electrolytic process, consisting in passing an electric current 

 through slender rods of the lower oxide in a bulb similar to that 

 of the incandescent lamp, meanwhile pumping away the oxygen 

 formed by the electrolysis as fast as it was formed. Pure tanta- 

 lum when fused forms a brilliant regulus having a platinum-gray 

 color, which can be hammered and drawn out into the finest wire. 

 The specific heat is -0365, and the atomic heat, 6*64, corresponds 

 to Dulong and Petit's law. The specific gravity of the cast 

 metal is 16*64. Its melting point was found to be 2250 to 2300°, 

 and is far above that of platinum. It remains brilliant upon 

 exposure to air, and oxidizes slowly when heated in air or oxygen. 

 The metal shows an extraordinary combination of the properties 

 of malleability, ductility, tenacity and hardness. For instance, 

 when a red hot piece of tantalum is put under the steam-hammer, 

 a plate of the metal is readily formed, which, when repeatedly 

 heated and hammered, attains a hardness equal to the diamond. 

 An attempt to bore such a plate one millimeter thick with a 

 diamond drill with 5000 revolutions per minute had to be aban- 

 doned after three days and nights of continuous work, as a depres- 

 sion of only one-quarter millimeter was made thereby, and the 

 diamond drill was much injured ; still the plate could be made 

 thinner by rolling, without losing its hardness. Many applica- 

 tions are predicted for this most wonderful metal, one of which 

 is the use of the wire for the incandescent lamp, in which it gives 

 more than double the efficiency of the carbon thread. — Zeitschr. 

 fur PJlectrochem., xi, 46. n. l. w. 



2. Gravimetric JDetermination of Nitric Acid. — M. Busch 

 has synthesized a base, diphenyl-endanilo-dihydro-triazol, named 

 " Nitron " for the sake of brevity and for commercial purposes^ 

 which forms a very insoluble, stable nitrate, and, therefore, 

 furnishes a means for the direct gravimetric determination of 

 nitric acid, as well as for its qualitative detection. The reagent 

 is manufactured on a commercial scale by Merck, and is employed 



