( 515 ) 



Bemarl'. The qnaiilily n^ = -- may also be obtained l)v llie opora- 

 tion fti=:g — .^•— . For tlic term — pf^F-fpF, occiUTing iji $, may 



be written — lpdV= — ETlog{V-b)—^. The required function of x 



may tlierefore also he found by calculating ( F'^zz />^ 



« Ö / a 



for which we then find exactly in the same way as above: 



b, ^ b,P 



The two methods of calculation are, of course, identical. The last 

 has the advantage, that we see at once that the difïerentialcoefficient 



of the correctionterm of ,ü, i.e. -yr- , is nothino- but x r — — , so 



O"* ^ (),?.''■' \b J 



that we have : 



.i; d.v 1-A' d,r d.v^ dx^\bj // ' 



Avhen S', (i\ and (i\ represent the quantities ?, ji^ and ft^ with omission 

 of the terms containing %(1— ,?•) and lor/ .v. As regards the quantity 



fto = T— , we must remember, that this is also obtained from the relation 

 d.v 



3. It is now the question, whether the expression 



' {l-{-r.vy 



represents the melting-points of the tin-amalgams as well as, or 

 better than my semi-empirical expression 



a, .v^ + /?, .f' + r, ,v\ 



Let us first observe, that van der Waals always found a^ neqntire 



in the case of electrolytes and other aqueous solutions (1. c. p. 195). 



Now it is evident, that if we may write a^^-=z \/a^a^, the coefïicient 



(bVa.-byay 



«1 becomes 1^ L_i ^, and ought tlierefore to be alwavs found 



6,' 



