. TRANSACTIONS OF THE SECTIONS. 29 
: media, Dr. Miller proceeded to explain his method of examining the subject. The 
light, being admitted by a longitudinal slit in a plate of metal, one half of this slit 
_ was covered with a vessel containing the gaseous medium, the other half transmitted 
ordinary light ; the image of the slit, after falling on a prism of Munich glass, was 
observed by a telescope. It was found that the dark lines of the spectrum materially 
changed their positions as different coloured gases were used ; and that, by subjecting 
the spectrum to the absorptive influences of chlorine, nitrous acid vapour, the vapours 
of iodine, bromine, perchloride, manganese, &c., numerous dark bands, not previously 
observed, were brought into view. Several of the oxides of chlorine were examined, 
and it was found that the chlorous acid, peroxide of oxide of chlorine and euchlorine 
all gave the same series of lines. The spectra produced by coloured flames were also 
examined, and many curious conditions observed. Dr. Miller had sought to ascertain 
if any relation could be found between the chemical characters of the bodies under 
examination and their properties of exhibiting Fraunhofer’s lines; but as yet no such 
relation could be detected. 
Contributions to Actino-Chemistry.—On the Chemical Changes produced by 
the Solar Rays, and the Influence of Actinism in disturbing Electrical Forces. 
By Roserr Hunt. 
He detailed a great number of experiments which supported his views, that a cer- 
tain class of chemical compounds possessed the property of fixing the chemical prin- 
ciple of light. The result of the researches of the author, since the York meeting, 
was that in all cases chemical action was either accelerated or retarded by the influ- 
ence of the actinic force, whatever it may be. It was evident that the peculiar elec- 
trical condition of the compound regulated the disposing power of the actinic rays ; 
but it was not yet determined if any constant relation was maintained between the 
electrical state and the action of this chemical power. The author found in all cases, 
that weak electrical currents which were sufficient to precipitate the metals from so- 
lutions in the dark, were not capable of doing so when they were exposed to sunshine, 
or even diffused daylight. The power of this principle in producing molecular dis- 
turbance was also mentioned, and many additional experiments were described, 
On the Manufacture of a Coloured Glass. By M. SpuirreEerser. 
I have the honour to present herewith small pieces of white glass, which are quite 
_ transparent, but contain however a portion of gold, which was added to the grit as 
chlorate of gold *, and which gives to this glass the curious quality to become red by 
slightly re-heating it over the alcohol lamp; a greater heat changes the colour, 
_ and the gold is restored to its characteristic tint, which quality has been long known, 
and employed by the crystal glass manufacturer. It is now the question, ix what 
state the gold is contained in the glass, when not at all coloured, and when coloured. 
In my opinion, the gold is in the white glass in the most oxidated state, analogous 
_ to the state of the lead in the white crystal glass, but, by re-heating, it loses a part 
’ 
: 
of the oxygen, and becomes more and more reduced. 
According to the opinion of other German philosophers, the gold is contained even 
in the white glass in the metallic state, but in a state of the greatest diffusion; and in 
_ the coloured condition in a state of less and less diffusion. 1 am not of this opinion, 
[ . . . 1 . 
_ because I have, by melting the red glass with a blowpipe supplied with oxygen gas, 
"made it again colourless, but only to a very small extent; and it is not very clear, I 
think, that the change of colour of this glass is the result of different states of deoxida- 
tion of the gold in it. But it is very curious that the glass does not become red by 
its first melting, and I can give no reasov for this phenomenon. In the Annals of 
M. Poggendorff I have noticed it last year; but I think that this phenomenon would 
be also interesting for a further optical investigation. 
* The composition of this glass is,— 
40 grains of .., sand. 
2D) aadaseesecasese SUDA. 
Dieacwasteecwatcet CUALK= 
ANA 0°52 ceccecsesseesee Gold, 
