**I. K. Garkushin, I. G. Yakovlev, A. I. Garkushin, E. S. Filatov, **

**O. V. Lavrenteva, A. V. Burchakov**

**ABSTRACT:**

The analytical description of the specific electrical conductivity of the polythermic method in the series of fluorides of the *s*^{1}-elements MF (M – Li, Na, K, Cs) is given by the function æ = *f*(*Z*), where *Z *is the ordinal number of the *s*^{1}-element for temperatures higher than the melting temperature at 5, 10, 50, 75, 100, 150 and 200°. The values of æ melts RbF and FrF for these temperatures were calculated from the dependences obtained and the dependences æ = *f*(*T*) were described analytically. The literature data are compared with the values of æ(RbF) and calculated in this paper. A comparative method describes the dependence æ_{T + n }= *f*(æ_{T + 5}), where *n *= 50, 100, 150 and 200° above the melting points of MF. It is shown that the description of æ(MF) by the equations in this work has a lower value of the standard deviation than the equations given in the literature. The description of æ(MF) by two methods showed a satisfactory convergence of the results of the calculation of æ(RbF) and æ(FrF).

**KEY WORDS: **

analytical description, forecast, melts of salts, alkali metal fluorides, specific electroconductivity, serial number, temperature