Intelligence and Miscellaneous Articles. 395 



An extended study of these various conditions lias led to the 

 elucidation of the nature of hardening, softening, tempering, an- 

 nealing, etc. of iron and steel, and has further shown that nu- 

 merical values may be assigned to these states. 



In brief, the research establishes : — 



1. The existence in steel, and in iron containing free carbon, of 

 a contraction or shortening which is excited by heat, and which pro- 

 ceeds simultaneously with the dynamical expansion and masks its 

 true amount. This is divisible into high and low temperature con- 

 traction. [Compare figs. 4 & 5.] 



2. The presence of a cooling expansion or crystallization, which 

 comes in during the dynamical contraction and masks its true 

 amount. 



3. These effects, due to crystallization and decrystallization, are 

 the causes of the so-called kicks, or temporary contractions and 

 expansions, A^hich occur during the heating and cooling of the steel. 



4. That the low-temperature contraction and cooling expansion 

 are due to decrystallization and crystallization which occur during 

 the acts of heating and cooling, while the kicks themselves are 

 simply the thermal effects associated with these changes, and are 

 proportionate to their extent/r 



5. That protracted annealing (that is, eictremely slow cooling) 

 brings about molecular separation of the carbon and iron ; and 

 steel in such a state contracts greatly when high temperatures are 

 reached, producing the contraction returns seen at the end of the 

 heating, and which are due to the condensation produced by the 

 recombination of the carbon and iron. Steels in this state are 

 less susceptible to cooling-expansion (crystallization), and therefore 

 to Ipw-temperature contraction on subsequent heating. [ Vide fig. 5.] 



Liy. Intelligence and Miscelhmeous Articles. 

 FRESH RESEARCHES ON THE METAL DAVYUM. BY M. SERGE KERN. 

 A S I intimated in my first ISTote addressed to the Academy, my 

 ■^-^ ingot of davyum weighed 0-27 grm. The metal was dissolved in 

 aqua regia in order to examine the action of different reagents upon 

 the solution. 



Potass gives a bright yellow precipitate of hydrate of davyum, 

 which is readily attacked by acids, even by acetic acid. The hy- 

 drate dissolved in nitric acid gives a brownish mass of nitrate of 

 davyum; on calcining this salt, a black product is obtained, which is 

 probably the monoxide. 



The chloride, dissolved in a solution of potassic cyanide, gives, 

 when the solution is slowly evaporated, beautiful crystals of a 

 double cyanide of davyum and potassium. The potassium in this 

 salt can be replaced by several metallic elements. Cyanoda^icacid 

 is very unstable ; it is isolated by passing a current of sulphuretted 

 hydrogen through a solution of a double cyanide of lead and 

 davyum. 



In acid solutions of davyum sulphuretted hydrogen produces a 

 precipitate of sulphuret of davyum, which is readily attacked by 

 the alkaline sulphurets, probably giving a series of sulpLo-salts. 



