76 Intelligence and Miscellaneous Articles. 



that the fragments of the metal were, soldered together at places, 

 under the influence of a partial softening : these numbers therefore 

 include a portion of the heat of fusion. 



4. The heat of fusion of gallium can be easily determined. By 

 introducing some crystals into the superfused gallium, the whole 

 of the metal crystallizes rapidly. At 13° I thus found +19*14 

 and +19*08, mean +19*11, for the unit of weight. 



This number remains sensibly the same for every temperature 

 between 30° and zero, on account of the specific heats of the liquid 

 and the solid being nearly identical. Eeferred to the atomic weight, 

 it becomes 1*33 calory. 



5. It will be observed that the two specific heats of gallium, taken 

 near the same temperature, are nearly identical. Mercury presents 

 the same peculiarity, its specific heat being, according to Regnault : — 



0*0319 between -40° and -78°; 

 0*0333 between zero and 100°. 



It is the same with the other metals. Thus the specific heat of 

 melted lead between 350° and 400°, according to Person 0*040, 

 exceeds by only one fifth that of the same metal, solid, at the ordi- 

 nary temperature, or 0*032. 



The same with tin (0*056 cold, 0*063 at about 300°). 



The same with bismuth (0*031 cold, 0*036 at about 320°) :— 

 slight deviations, attributable in great measure to the difference of 

 the temperatures, as the specific heats go on increasing with the 

 temperature. It may be assumed that the solid and liquid specific 

 heats of all these metals, if taken at the same temperature, would 

 have values very near one another. 



6. The atomic weight of gallium, recently determined by M. 

 Lecoq de Boisbaudran, being 69*9, its specific heat in the liquid state 

 is equal to 5*59, in the solid state to 5*52. 



This product is the same for aluminium, or 5*53 (Kopp), and 

 for glucinium, according to MM. JNlllson and Pettersson's new 

 measurement, or 5*64. 



"With these may be compared the analogous metals, such as zinc, 

 6*08 (Kopp), and magnesium, 5*88 (Kopp). 



Manganese (6*69), so similar to the last metals, and crystallized 

 silicium (4*62), of which the oxide and chloride, on the contrary, 

 remind us of aluminium, give products which deviate much, and in 

 opposite directions, although by quantities nearly equal, when 

 compared with the atomic specific heat of aluminium : the total 

 deviation here amounts to nearly 50 per cent. 



I shall not here repeat what I have had occasion to say in this re- 

 spect relative to the limits of theoretic and practical uncertainty of the 

 law of Dulong and Petit in its applications to solid elements (see 

 Comptes Bendus, t. lxxxiv. pp. 1261-1276). In reality that law 

 only presents a precise and incontestable meaning for the simple 

 gases, the only bodies for which it is permissible to assume that one 

 aud the same rise of temperature answers to one and the same in- 

 crease of vis viva under the same volume. — Anncdes de Chimie et de 

 Physique, October 1878, t. xv. pp. 242-244. 



