D. CHEMISTRY AND METALLURGY. 91 



From the observations made during the partial phase the 

 law was deduced " that the diminution of the total chemical 

 intensity of the sun's disk during an eclipse is directly pro- 

 portional to the magnitude of the obscuration." 21 A,I)ec., 

 1871,1141. 



GLYCOL-STRYCHNINE. 



The detection of a new base from strychnine, to be named 

 glycol-strychnine, has lately been announced. 1 A, Dec. 1, 

 1871,263. 



SEPARATION OF PURE NITROGEN. 



Pure nitrogen, it is reported, can be prepared by means of 

 bi-chromate of ammonia, which, when heated in a retort, is 

 transformed into gaseous nitrogen, water, and green chrome 

 oxide. 15 C, xxi., 1871, 376. 



CUPRO-AMMONIUM. 



If shreds of copper are introduced into a bottle half full of 

 ammonia solution, the metal will be dissolved, with the pro- 

 duction of what is called cupro-ammonium, and with the ac- 

 companiment of a deep blue color. This substance has the 

 remarkable property of dissolving various substances, as silk, 

 lignine or cellulose, paper, etc., with great rapidity. It has 

 been proposed to apply this agent in the preparation of solu- 

 tions which can be converted to important industrial uses, 

 such as readily suggest themselves in connection with this 

 power of dissolving the substances in question. Paper, linen, 

 wood, etc., can be readily united almost indissolubly by means 

 of this substance ; and it is said that, when thus adherent, the 

 copper which they hold may be extracted by a weak acid, 

 leaving the material pure and white, but without disturbing 

 the adhesion already established. It is not known in what 

 particular chemical combination the two substances unite, or 

 what is the precise character of their union. The name given, 

 cupro-ammonium, is to be considered as of no chemical sig- 

 nificance. 6 Z>, April 20, 1872, 256. 



ACTION OF NITRIC ACID ON METALS. 



Some time ago it was announced that tin is not affected by 

 nitric acid of 1.42 specific gravity as long as it is in contact 



