TRANSACTIONS OF THE SECTIONS. 65 
the nutritive value of the fungi. The nutritive value of fungi has thus been over- 
rated considerably ; and there can be little doubt that the same is the case with many 
vegetables, which, according to the author’s experiments, contain sometimes consider- 
able quantities of ammonia in the form of ammoniacal salts, 
Results of a Research on Aitherification. By Prof. A. W. W1LLiAMson. 
The process by which this remarkable transformation of the elements of alcohol is 
- effected has been the subject of much discussion among chemists; of the two theories 
which have been devised to explain it, each counts among its supporters many first- 
rate chemists. 
The facts upon which the contact theory lays peculiar stress are more physi- 
cal than those to which the appropriately-designated chemical theory refers for its 
evidence. But there is one point upon which the two differ essentially, and that is 
the composition of alcohol; the one maintaining that the two products, ether and 
water, are made from 2 atoms of alcohol; the other, that they are both produced from 
1 atom of double size. This is a difference of fact, and is therefore susceptible of 
being decided by experiment, as it requires nothing more than a direct evidence of 
the relative atomic weights of alcohol and zther. 
An experiment was accordingly devised, of such a nature as to give a result according 
to the simple, differing from that according to the double atomic weight of alcohol. 
It consisted in making ether from alcohol by a new process, in which the various steps 
of which it consists were performed separately. One-sixth of the hydrogen of alcohol 
-was first expelled by the action of potassium ; this compound differs from zther by 
having half as much carburetted hydrogen as that body to an equivalent weight of po- 
tassium to the other half, or by doubling its atomic weight, may be supposed to contain 
zther and potash. By double decomposition with iodide of zthyle, this substance was 
converted into ether, and not into a body of double the atomic weight of zther, which 
would have been the case according to the chemical theory of zxtherification. By 
acting upon the same potassium compound with other iodides, new ethers were ob- 
tained, which to 1 atom of oxygen contained two different carburetted hydrogen atoms, 
one of which was contained in the alcohol, the other occupied the place of the hy- 
drogen of that body. 
In the common process of etherification, sulphovinic acid is known to be the im- 
mediate product of the action of the sulphuric acid upon the alcohol. Now this sul- 
phovinic acid is strictly analogous to iodide of zthyle and iodide of hydrogen. To 
convert alcohol into zther, it has merely to exchange its ethyle for the hydrogen, 
which in the preceding experiment was expelled by potassium. It is thus reconverted 
into sulphuric acid, to recommence a similar circle. 
The continuous action of the reagent sulphuric acid, of which a given quantity is 
known to be capable of converting an unlimited amount of alcohol into ether and 
water, is thus owing to an exchange of analogous molecules in alternately opposite 
directions, and is distinctly different from any effect of chemical affinity. 
On the Influence of Sunlight over the Action of the Dry Gases on Organic 
Colours. By Guorce Wixson, M.D., F.R.S.E. 
The object of this communication is, to report the result of a series of experiments 
made this summer, on the effect of sunlight in modifying the chemical action of eight 
different dry gases, viz. chlorine, sulphurous acid, sulphuretted hydrogen, carbonic 
acid, a mixture of sulphurous and carbonic acid, oxygen, hydrogen and nitrogen on 
organic colouring matters. I had ascertained the action of the gases mentioned 
already, on vegetable colouring matters, so arranged, that both colouring matter and 
gas should be as dry as possible, the aim of the inquiry being to elucidate the theory 
of bleaching, by accounting for the inaction of dry chlorine upon dry colours. In the 
course of this inquiry, I ascertained that in darkness dry chlorine may be kept for 
three years in contact with colours without bleaching them, although when moist it 
destroys their tints in a few seconds, and I thought it desirable to ascertain whether 
_ dry chlorine was equally powerless as a bleacher when assisted by sunlight. The 
1850. F 
