50 



Scientific Intelligence. 



Argon in 100 volumes, 

 of atmospheric of air con- 

 nitrogen, taining 7 9 "04 

 of nitrogen. 

 Air taken in Paris at about 10 m. above 



the ground, Sept. 25 1-185 0*9369 



" 26 1-183 0-9349 



" 30 1-185 0-9367 



Oct. 1 1-180 0-9325 



" 4 1-185 0-9363 



Air taken in Normandy on a hill 305 m. 



high 1-182 0-9343 



Air taken at a height of 300 m. on the 



Eiffel Tower 1-180 0*9328 



Air taken in an iron mine _ 1-183 0*9534 



The above results are not corrected for a supposed constant 

 loss in analysis of about 0*7 per cent. Making this correction, 

 the average results for normal air become 1*192 and 0*941. The 

 variations in the results are within the limits of experimental 

 error, and it must be concluded that argon, like oxygen and 

 nitrogen, in the air is practically constant in amount. — Gompt. 

 Rend., cxxi, 604. h. l. w. 



2. A study of Graphite occurring in Pegmatite. — Having 

 previously shown that all other forms of carbon are converted 

 into graphite at the ordinary pressure by a sufficient rise of tem- 

 perature, and further that all the graphites produced by crystalli- 

 zation from molten metals possess the property of sprouting 

 when heated after the addition ot a little nitric acid, while, on 

 the contrary, graphites produced by simple transformation by 

 heat or by volatilization in the electric arc do not sprout when so 

 treated, Moissan has now examined, in this way, a graphite 

 occurring in a pegmatite rock. This graphite was found to 

 sprout, and the author believes that it must have been formed in 

 a manner similar to that produced from molten metals, and that 

 it existed before the pegmatite was formed. Continuing this 

 research, the author has examined a number of other natural 

 graphites from various parts of the world, and finds that a part 

 of them sprout while the others do not. He concludes that the 

 first class seem to have been produced by the action of molten 

 baths, especially of metallic baths, while the second class were 

 evidently formed by the action of an elevated temperature upon 

 any variety of amorphous carbon. — Compt. Rend., cxxi, 538, 542. 



h. l. w. 



3. The Volumetric Determination of Cyanogen. — The method 

 of Liebig is carried out by adding a standard solution of silver 

 nitrate to that of the alkaline cyanide in which cyanogen is to be 

 determined, until a permanent precipitate of silver cyanide 

 appears. One atom of silver corresponds to two cyanogens. 

 Deniges has now modified this well-known method so as to 

 greatly improve the delicacy of the end-reaction and to widen 



