66 Scientific Intelligence. 



tion ; that is to say, a state of tension of their components. 4th. 

 There are compounds which determine and which regulate the 

 chemical equilibrium between antagonistic bodies, according to 

 the conditions of their own existence and of their dissociation; it 

 is at this point that the physico-chemical laws of dissociation 

 intervene, laws which are the objects of study at present by so 

 many savants. A fundamental distinction is thus established 

 between those reactions which are due to the internal energy of 

 systems, energy the gradual dissipation of which is conformable 

 to the principle of maximum work, and those opposite effects 

 which are due to foreign energy, such for example as calorific 

 energy which acts generally to produce changes of state and dis- 

 sociation. The whole of the mechanics of chemistry is explained 

 by the coaction of the laws which preside over these two orders 

 of phenomena. — Ann. Chim. Phys., vi, x, 123, January, 1887. 



G. F. B. 



7. On a new Color reaction for Bismuth. — Haselbroek has 

 studied the action of hydrogen peroxide upon bismuth salts and 

 finds that if a weak solution of the peroxide made alkaline with 

 potassium or sodium hydrate, be added to bismuth subnitrate in 

 a test tube, the white subnitrate on heating becomes brownish 

 yellow, the mixture at the same time evolving oxygen. The 

 bright orange-yellow powder thus obtained is amorphous, becomes 

 brown on heating, and dissolves in mineral acids with evolution 

 of gas, oxygen when sulphuric acid is used, chlorine when hydro- 

 chloric acid is employed. Analysis showed it to be bismuth pent- 

 oxide, Bi 2 6 , already observed by Arppe, and capable of forming 

 bismuthic acid. The formation of this body is a delicate test for 

 bismuth. If bismuth hydrate is precipitated in presence of hydro- 

 gen peroxide and excess of alkali or ammonia, the slightest trace 

 shows a yellow color. If a drop of a 3 per cent peroxide solution 

 be diluted with 150 co water, made strongly alkaline, and a few 

 drops of a dilute solution of bismuth nitrate be added the yellow 

 precipitate appears on warming. One part of H 2 2 in 100,000 of 

 water may thus be detected. It also constitutes an extremely 

 delicate test for bismuth. — JBer. JSerl. Chem. Ges., xx, 213, Feb., 

 1887. G. F. B. 



8. A new Heat Measurer. — Mr. C. Vernon Boys exhibited an 

 instrument which he terms the Radiomicrometer to the Royal 

 Society, March 24. The instrument is a modification of one in- 

 vented by M. D'Arsonval, and consists of a minute thermal junc- 

 tion forming one side of a parallelogram of which the other three 

 sides ai*e of copper. This thermo-electric circuit is suspended 

 between the poles of a magnet. It is evident that when radiant 

 heat falls upon the thermo-electric junction forming one side of 

 the parallelogram an electrical current is formed which turns in 

 the magnetic field, where it is placed so as to include the greatest 

 number of lines of force. The parallelogram made by Mr. Boys 

 embraced one square centimeter. The thermo-electric junction 

 consisted of a bar of antimony and of bismuth, each piece being 



