402 Scientific Intelligence. 
e T 
are absorbed by the green leaves of plants, and the energy which 
is stored up in the form of chemical force in the interior of the 
ants. We are not yet able to make so accurate a measurement 
of both these stores of energy as to be able to show that there is 
an equivalent proportion. We can only show that the amount of 
energy which the rays of the sun bring to the work is completely 
carbon which during one year, on the surface of a square foot m 
our latitude, can be produced under the influence of ‘solar rays. 
This quantity, when used as fuel and burnt to produce carbonic 
acid, gives so much heat that 291 Ibs. of water could be heated 
1 N 
comes down during a year to one square foot is sufficient to raise 
the temperature of 430,000 Ibs. of water 1°C. The am 
of heat which can be produced by fuel growing upon on Mi 
foot during one year is, as you see from these figures, a very ea 
fraction of the whole amount of solar heat which can be produ 
by the solar rays. It is only the 1477th part of the whole are 
of solar light. It is impossible to determine the quantity of sir 
eat so accurately that we could detect the loss of so sm 
a fraction as is absorbed by plants and converted into other sagge 
of energy. Therefore, at present, we can only show that the 
sidering that active growth only takes place during five eee i 
the year, we may safely adopt ;4, of the total energy of ee 
as a fair value of the conserved power, on a given area of t : 
. earth’s surface in this latitude during the course of the pone 
As chlorophy] in one or other of its forms is the substance throug! 
which light becomes absorbed and chemical decomposition ¢™ 
i i a 0 
sues, it would be interesting to acquire some ide the eg 
ed by a given erea of leaf-surface bacon. ple 
course of a day, and to compare this with the total availa 
ties, provided we could determine the equation of chemical trans 
