Upon Calorie as a Cause of Galvanic Currents. 277 
results, but, the combinations being extremely weak, the effects are 
difficult of observation. 
The combination between zinc and mercury will enable us to trace 
the relation which the direction of the caloric bears to that of the 
positive current, for if these metals are heated together, the mercury 
transmits a negative current. The contrary is shown. to be the case 
when this metal gives out caloric to the zinc, and the inference, there- 
fore is, that in the usual combination, where contact is first establish- 
ed, the mercury receives caloric from the zinc, and, accordingly, 
the caloric and positive current must move in opposition to each oth- 
er. This result corresponds with the law of its own particles, as giv- 
en in the table, and is moreover exemplified by the combinations 
between mercury and the metals, iron, silver, antimony, tin and ar- 
senic, provided these metals are made hotter than the mercury. 
The caloric and positive current move together, however, in the 
combinations of hot mercury and cold iron, cold any and = 
arsenic. 
The other thermo-electric combinations furnish results which vary 
for each case; it will-not, therefore, be necessary to explain their 
meg irk farther than by the tabular view which follows, and with 
hI shall close this communication. ‘The relative direction of 
Ms ‘ae and galvanic currents may thus easily be perceived, and 
by consulting the table already given for the elementary condition of 
each metal, under the influence of temperature, we may generally 
arrive at a knowledge of that one which governs the currents. To 
facilitate the application of the principles indicated in the preceding 
remarks, I have represented the direction of the caloric by an arrow 
with a head composed of dots, and feathered at right angles to the 
shaft. The course of the positive galvanic current is indicated, on 
the other hand, by an arrow of the usual form. 
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