Chemical Science. 405 



same ten degrees, the specific heat of the metal or alloy may be 

 easily determined ; for as all external circumstances and the difference 

 of temperature are the same, the loss of heat which mercury expe- 

 riences will be, to that of the alloy, in the ratio of the different 

 lengths of time ; and as, by the experiments of MM. Dulong and 

 Petit, the specific heat of mercury has been ascertained both for 

 high and low temperatures, that of the alloy may accordingly be cal- 

 culated. 



Whilst determining, in this manner, the specific heat of lead and 

 tin, and several of their alloys, at different temperatures, I found, in 

 general, the thermometer to be stationary at two points one of 

 which was the same for all alloys of the same nature, whilst the other 

 varied according to the proportion of the two metals. I then exa- 

 mined the alloys of other metals, and obtained a similar result, as 

 will be seen from the annexed table, which exhibits the observations 

 on the alloys of lead and tin, tin and bismuth, and tin and zinc. 

 The metals were combined in their simple atomic proportions, as is 

 indicated by the number affixed to the initial of each metal. 



The first table contains the observations on lead and tin ; the for- 

 mer of which becomes solid at 325 C., the latter at 228 C. In the 

 alloys, the thermometer was stationary at 167 C. ; and the length of 

 time, between 190 and 180, is accordingly much more considerable 

 than that of any of the preceding or following ten degrees. Besides 

 this fixed point, (as it might perhaps be called, with reference to the 

 other variable one,) there are other retardations of the thermometer, 

 according to the proportion of the respective metals ; as, in L 3 T, 

 between 290 and 180 of 1' 36", in L 2 T between 280 and 270, of 

 1'6", &c. On increasing the quantity of tin, the variable was ob- 

 served to approach the fixed point, and in the alloy L T 8 they coin- 

 cided ; in L T 4 the thermometer was stationary for a few moments 

 when at 190, or just below, and then suddenly fell to 187. In L T 8 

 the retardation became again more distinct, being of 3' 5" between 

 210 and 200 ; and in LT 12 , of 4' 23", between 220 and 210. 



It seems then that there exist, for all alloys of lead and tin, (except 

 for L T 3 ,) two points at which the thermometer is stationary the 

 one which is fixed at 187, the other being variable, according to the 

 proportion of the metals, but always at a higher temperature the 

 more distant the mixture is from the combination L T 3 . The length 

 of time during which the thermometer is stationary on the fixed 

 point also decreases in the same ratio, until it becomes =0 ; when 

 the metals are simple, the fixed point is then the same with that 

 of their congelation. 



The second table gives the result of the observations on the alloys 

 of tin and bismuth; the fixed point is 143, the variable point 

 evidently coincides with the fixed one in T 8 B 2 ; and, according 

 to the different proportions of the alloy, is near to, or distant from, 

 the temperature at which the simple metals become solid. 



The third table contains the experiments on the alloys of tin and 



