824 Prof. F. Hosetti's Experimental Researches 



curve, its downward tendency at the points referred to being 

 merely the expression of the facts. 



By taking the atomic weights of the elements as abscissae 

 and the reciprocals of the corresponding melting-points as 

 ordinates, a curve is obtained which has a form similar to that 

 of Meyer's (in which the ordinates represent the atomic 

 volumes); for, as in the latter, we have at the maxima the 

 halogens and alkali-metals, and at the minima 0, Si, Ti, Mn, 

 Zr, Pt, and allied elements. 



-Mechanical Arrangement of the Elements, — If the elements 

 are arranged in the order of their atomic weights so that the 

 first member of each horizontal series follows directly after 

 the last member of the preceding series, B after Be, Al after 

 Mg, &c, and if, with Lothar Meyer (Die modernen Theorien der 

 Chemie, p. 301, 2nd edition), we imagine that the Table is 

 rolled round a perpendicular cylinder in such a way that the 

 group beginning with B and Al joins on to that of the alka- 

 line-earth-metals Ba, Mg, Ca, &c, then we obtain, as is readily 

 seen, a continuous series of all the elements arranged in a 

 spiral according to the size of their atomic weights. Those 

 elements which in this arrangement stand directly under one 

 another on the cylinder belong to the same group. It is thus 

 evident that by arranging the elements in this mechanical 

 manner we obtain a truly natural scientific classification. 

 [To be continued.] 



XXXYIL Experimental Researches on the Temperature of the 

 Sun. By F. Rosetti, Professor of Physics in the University 

 of Padua*. 



THE question of the effective temperature of the sun has 

 been keenly discussed of late years, although as yet with- 

 out any definite result. Newton was the first to attack this 

 problem; it was afterwards studied by Saussure, and more 

 recently by Pouillet, Waterston, Secchi, Ericson, Yicaire, 

 Violle, Crova, and others. 



Although the observations on radiation made by these in- 

 vestigators were tolerably concordant, the conclusions at which 

 they arrived as regards the temperature of the sun are widely 

 different. Thus Newton, Waterston, Ericson, and Secchi 

 affirm that the temperature of the sun cannot be less than from 

 one to two million degrees ; on the other hand, Pouillet, Yicaire, 

 Yiolle, and others maintain that it is not above 1500°, or at the 

 very most 2500°. 



* Translated from the Ann, de Chim, et de Phys. t. xvi. (1879) by John 

 I. Watts, Owens College. 



