131 
an aqueous solution of caustic soda, when after two hours 
the moistened fracture of the wire connected with the zinc 
pole of the battery was found to bubble. Twenty two hours’ 
longer immersion, the battery working all the time, caused 
the bubbles to be more abundant ; the toughness of the wire 
was also diminished, and its surface was blackened. The 
wire at the positive pole was however unchanged either on 
the surface or in toughness. 
Three pieces of wire, each 12 inches long, were immersed 
in hydrochloric acid about 1*2 sp. gr., one being connected 
with the positive pole, the other with the negative pole of 
the battery, and the third unconnected with the battery. 
At the expiration of half an hour the two last pieces were 
found to bubble on being fractured, and were also more 
brittle. The one however connected with the positive pole 
was not in the least affected. Thus showing that simple 
immersion in acid is not stifficient to produce in iron the 
remarkable changes before described, unless it be accom- 
panied by evolution of hydrogen. 
In conclusion, if the oxidation of the surface of iron be as 
a rule accompanied by the absorption of nascent hydrogen 
into the interior of the iron, then the diminution of strength 
and toughness consequent on this will affect iron ships, 
telegraph cables, and other structures in which iron is 
lai'gely used and which are constantly immersed in water. 
“Does the Earth receive any Heat directly from the 
Sun,” by Henry H. Howorth, Esq. 
The term heat is one of unusual ambiguity. It has at 
least two meanings, which, if they do not exclude one 
another, are at least not commensurable. Their indefinite 
and careless use has created great confusion. The first 
meaning connotes the feeling heat, a purely subjective 
matter, whose investigation is a proper subject for meta- 
physical students, but with which we have nothing to do 
