292 Intelligence and Miscellaneous Articles. 



At the critical point the heat of evaporation is exactly null, as the 

 tangent to the curve X =f(t) is here at right angles to the abscissa- 

 axis. The author concludes from the preceding that for carbonic 

 acid and nitrous oxide at any rate the specific heat of saturated 

 vapour near the critical point is negative, and increases without 

 limit with the absolute value. The observation on the specific heat 

 of saturated vapour is further made, that this function is a maximum, 

 and has possibly two points of inversion. — Beiblatter cler Physik, 

 vol. xiv. p. 1197 ; Doctor thesis, Paris, 1890. 



ON THE THEKMAL EXPANSION OF SOME AMALGAMS IN THE 

 LIQUID STATE. BY C. CATTENEO. 



The object of these researches has been to investigate certain 

 amalgams, so as to ascertain whether in the case of perfect lique- 

 faction the approximate law is verified that the metals retain their 

 respective coefficients of expansion, and if, on the other hand, their 

 formation was accompanied by an appreciable change of volume. 

 Also to study these various amalgams of zinc, so as to calculate 

 the density and the coefficient of expansion of this metal in the liquid 

 state. 



From his experiments the author thinks he can deduce the 

 following conclusions : — 



1. When the quantity of tin, of lead, or of zinc entering into 

 the composition of an amalgam is small, the expansion of the 

 amalgam is not equal to the sum of the expansion of the metals 

 which form it. 



2. When, on the contrary, the amalgam is dry, the comparison 

 of the coefficients of expansion calculated from those given by 

 experiment, show that with a sufficient approximation the metals 

 may be regarded as retaining respectively their coefficients of 

 expansion. 



The amalgams in question have exhibited a contraction. This 

 contraction is however, very feeble in the case of very concen- 

 trated amalgams. 



The values found for the densities of tin, of lead, and of zinc in 

 the liquid state at their respective temperatures of fusion, and for 

 their coefficients of expansion in this same state, are sufficiently 

 accordant with those given by Yicentini and Omodei ; from which 

 it may be concluded that, like that of alloys, the investigation of the 

 thermal dilatation of amalgams, provided they are sufficiently 

 concentrated, may serve to determine directly with a sufficient 

 approximation the density and coefficient of expansion of a metal 

 in the liquid state. — Journal de Physique (ii.) vol. ix. p. 519, from 

 Atti della R. Accademia delle Scienze di Torino, vol. xxv. p. 492. 



