104 Miscellaneous. 
instance, the combustion of one pound of hydrogen gas will raise 
the temperature of 33,808 lbs. of water one degree of the centi- 
grade scale, while the burning of a pound of tin will raise the 
temperature of only 1,144 lbs. of water one degree. But the 
pound of hydrogen in burning combines with 8 lbs. of oxygen, 
while the pound of tin combines with only one-fourth (#$ths) of a 
pound of oxygen. A simple calculation will show that the 
quantity of heat generated by the combination of a pound of 
oxygen 1s very nearly the same in both cases. A pound of oxygen 
in burning hydrogen will raise the temperature of 4,226 Ibs. 
of water one degree, while in burning tin it will raise the tempe- 
rature of 4,230 lbs. of water one degree. This law does not 
hold, however, in cases where the combustible in burning under- 
goes a change of form, from the gaseous to the solid, or from the 
solid to the gaseous state. For instance, carbon in burning to 
carbonic oxide is changed from the solid to the gaseous form, and 
in this case a pound of oxygen generates only 2,962 units of heat, 
while in burning this carbonic oxide into carbonic acid, where no 
change of form takes place, a pound of oxygen generates 4,258 
units of heat. In burning zinc the oxygen.is changed from the 
gaseous to the solid state, and in this case a pound of oxygen 
generates 5,285 units of heat. When either the combustible or 
the oxygen is changed from the solid to the gaseous form, a 
portion of the heat is absorbed, and the amount of sensible heat 
is diminished ; but when the change is the opposite way the 
sensible heat is increased. Even where no change of form occurs 
in either of the combining elements, the amount of sensible heat 
developed may be modified by a change of volume; an increase 
of volume dimishing the sensible heat, and a contraction of 
volume adding to the heat set free. 
THE THAMES SaLMoN.—The capture of a salmon in Long 
Reach must be a source of great gratification to all lovers and 
promoters of pisiculture. The following letter goes a long way 
to prove that it was hatched in the Thames Angling Preservation 
Society’s apparatus at Hampton :—To the Editor of the “Times.” 
Sir,—I have received several communications relative to the 
salmon taken at Long Reach. All are agreed in believing that — 
it is one of those hatched in the Thames Angling Preservation 
Society’s apparatus at Hampton. If the small fry were facetiously 
described as Mr. Ponder’s babies from the interest and care he 
took in them, both he and Mr. Buckland need justly be proud of 
this full-grown fish, and the angling public ought to fill the treasury 
of the society to enable the committee more largely to develope 
this portion of their work after so successful a result. I need 
scarcely add that any amount of labour which is given to me in 
the acknowledgment of contributions will be cheerfully rendered, 
and I shall be glad to have my services taxed to the utmost in 
discharging so pleasant a duty—W. H. BroucHam, Hon. Sec. _ 
11 Adam street, Adelphi, W.C., Aug. 15. ; 
