1853.] OF THE ROYAL INSTITUTION, 325 
flue without injuring the architectural appearance of the room. The 
public at large will therefore still await the removal of the objec- 
tionable compounds in question, by the gas manufacturer, before 
they will universally adopt this otherwise delightful means of artificial 
illumination. 
There are yet several other points of an economical and sanatory 
nature connected with the use of artificial light, but time does not 
permit of their discussion. 
Tn conclusion, whilst coal gas is indisputably the most economical 
means of illumination, different varieties of that gas possess exceed- 
ingly variable values which ought to be known by the consumer, 
The high sanatory position which gas takes, with regard to the 
production of a minimum amount of carbonic acid and heat, for a 
given amount of light, ought to stimulate the manufacturer to perfect 
the process, by removing all sulphur compounds, and attaining the 
most desirable composition, so that this economical, and, if pure, 
agreeable and sanatory light, may contribute to our domestic com- 
fort to a much greater extent than it has hitherto done. 
WEEKLY EVENING MEETING, 
Friday, May 27. 
Ricut Hon. Baron Parxg, Vice-President, in the Chair. 
B. C. Broprz, KEsqa., F.R.S. 
On the formation of Hydrogen and its Homologues. 
In, what is termed, mineral chemistry, chemical substances are 
classified according to the different nature of the elements of which 
they consist. But in organic chemistry this distinction is no longer 
available. Organic substances were formerly defined ‘as triple 
compounds of carbon, hydrogen, and oxygen, and this, with the 
statement of the relative proportion of these elements in any given 
compound, was all that was attempted to be made out as to its 
constitution. But this class of bodies is more numerous, possibly, 
than all the other chemical substances taken together, with which 
we are acquainted, and some further distinction was necessary for 
the purposes of science. The sagacity of certain chemists at length 
discovered a relation which was capable of becoming the basis of 
a truly rational and natural classification. It was perceived that 
in the long series of chemical changes of which these bodies were 
susceptible, the whole of the substance did not change, and that, 
