158 REPORT—1850. 
radiation is capable of producing a sensible action on surfaces rendered per- 
fectly free from organic matter. ‘Those interested in this branch of inquiry 
are referred to the ‘ Scientific Memoirs,’ since the subject can scarcely be said 
to belong to this Report. 
I have purposely avoided any special notice of the photographic processes 
which have been discovered during the progress of the investigations we have 
been considering. Herschel, Talbot, Woods, Fyfe, Penton, the writer of this 
Report, and others, in our own country, have introduced new processes ; and 
Daguerre, Becquerel, Lassaigne, Fizeau, Everard, Niepce, &c. on the continent 
have enriched our store. Improvements in the Daguerreotype have been 
effected by Goddard, Claudet and others, until they have brought the silver 
plates to a state of sensibility which is almost marvelous. We have recently 
been surprised with an announcement, that by the agency of fluorine the pro- 
cesses on paper are rendered instantaneous, particularly on the calotype variety. 
In justice to myself, I must however claim to have published, in 1844*, a pro- 
cess called by me “‘ the Fluorotype,” which corresponds with the process now 
introduced in France, and which enabled me, with a non-achromatic meniscus 
lens, to procure ‘‘ good images in the camera in half a minute.” If the differ- 
ences between the lenses employed be taken into account, it will be found 
that the result I then obtained was equal to that of which the discoverer of the 
new process (?) now boasts. 
It will be evident that the question which assumes the most prominence 
in our consideration of these remarkable phenomena is that of the identity 
or otherwise of light and actinism. 
Fresnel has stated that the chemical effects produced by the influence of 
light are owing to a mechanical action exerted by the molecules of zther on 
the atoms of bodies, so as to cause them to assume new states of equilibrium 
dependent on the nature and on the velocity of the vibrations to which they 
are subjected. 
Arago says‘, it is by no means proved that the photogenic modifications of 
sensitive surfaces result from the action of solar light itself. These modifica- 
tions are perhaps engendered by invisible radiations mixed with light properly 
so called, proceeding with it, and being similarly refracted. 
These views fairly represent the condition in which ithe argument stands, 
and a yet more extensive set of experiments appears to be necessary before 
we can decide the question. It appears however important that we should 
dismiss, as completely as possible, from our minds, all preconceived hypo- 
theses. The phenomena were all unknown when the theories of emission 
and of undulation were framed and accepted in explanation of luminous effects ; 
and it will only retard the discovery of the truth, if we prosecute our researches 
over this new ground, with a determination to bend all our new facts to a 
theory which was framed to explain totally dissimilar phenomena. 
We may sum up the amount of our knowledge of the chemical influences 
of the solar radiations as follows :— 
1. The rays, having different illuminating or colorific powers, exhibit 
different degrees and kinds of chemical action. 
2. The most luminous rays exhibit the least chemical action upon all in- 
organic matter. The least luminous and the non-luminous manifest very 
powerful chemical action on the same substances. 
3. The most luminous rays influence all substances having an organic 
origin, particularly exciting vital power. 
4, Thus, under modifications, chemical power is traced to every part of the 
* Researches on Light, p. 106. + Comptes Rendus, 1843. 
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