B.OYAL INSTITUTION. 
493 
in four of pure acid. Certainly this is the only solution which any chemist would be 
justified in dispensing as the ‘solution of best medicinal carbolic acid,’ and the dose of 
such a solution recommended by Mr. Foster, if administered to young children, could 
scarcely fail to prove fatal.” 
__ On the other hand, we learn from the ‘Lancet ’ of January 23rd that Dr. Alexander 
Iveith has given, in similar cases, carbolic acid, combined with acetic acid and opium, in 
doses of four to six drops, with success, the patients rather liking the dose than otherwise. 
ROYAL INSTITUTION. 
The first of the Friday evening meetings at the Royal Institution was held on the 
15th of January, when a very large number of members and their friends assembled to 
hear a lecture by Professor Tyndall, F.R.S., “ On Chemical Rays and Molecules.” 
The Professor stated that the first physical investigation of importance in which he 
ever took part was published under the title of “ The Magneto-Optic Properties of Crys¬ 
tals, and the Relation of Magnetism and Diamagnetism to Molecvdar Arrangement,” 
which researches had been prosecuted jointly with Professor Knoblauch. These early 
researches led him to reflect upon the probable architecture of the invisible atoms which 
build up crystals, causing him to try to penetrate a mysterious field of science beyond 
the direct observation of the senses, and to make radiant heat the agent to unlock some 
of these secrets of nature. Thus was his mind turned more especially towards that 
branch of philosophy known as “molecular physics;” and in the subsequent researches 
he often had occasion to enclose invisible vapours and gases in tubes, to w r atch their be¬ 
haviour when submitted to the action of radiant heat. Two or three months ago, while 
sending an intense beam from that brilliant little artificial sun—the electric light— 
through a vapour enclosed in a tube, he was surprised and somewhat annoyed to see a 
cloudiness in the path of the rays. He was annoyed because he thought that perhaps, 
in previous experiments, he had ascribed absorption of heat to true transparent vapours, 
which absorption might in reality have been due to faint clouds in the tube. Ou fur¬ 
ther examination, however, he saw that there was no cloud in the tube in the first in¬ 
stance, but that the light itself manufactured the cloud, by setting up chemical decom¬ 
position in the vapour. He would show one of the experiments by filling the tube with 
nitrite of amyl vapour. (He then passed some of the common air from the lecture-room 
through a tube filled with cotton-wool to filter the particles of dirt out of it. The car¬ 
bonic acid was next abstracted from the air by its passage through a tube filled with 
marble and caustic potash, and lastly, the purified air was dried by passage through a 
tube filled with powdered glass and sulphuric acid. The pure air was then made to 
bubble through nitrite of amyl, an almost colourless liquid, from which it took up some 
vapour, and then passed into the great experimental tube. Upon sending a powerful 
beam from the electric lamp through the transparent vapour, a cloud of little liquid par¬ 
ticles was quickly formed at the end of the tube nearest the light.) With reference to 
this experiment, he said the vapour of nitrite of amyl should be pictured as composed of 
a vast number of molecules in incessant motion. Each molecule, again, is itself built 
up of numerous atoms, which, between the forces of attraction and repulsion, vibrate 
with respect to each other, to and fro over their position of equilibrium. Now, when 
weaves of light rush against these atoms, they shake them, and accelerate their motions. 
Nay, sometimes they shake them rudely asunder, a new chemical substance is formed, 
and that substance becomes visible. Such was the case in the experiment with nitrite 
of amyl, for the waves broke up the vapour into a new substance, composed of small 
liquid spherules, which made their presence visible as cloud. The reason the cloud was 
seen at one end of the tube, and not at the other, was that the vapour at one end, having 
drunk in and absorbed all the energy of the waves, the latter had not sufficient force 
left to decompose the further length of vapour. He would reverse the ends of the tube 
by putting the transparent end next the light, and now they saw that a cloud had formed 
at that end also. Into another large tube he would now admit some vapour of nitrite 
of butyl, mixed with hydrochloric acid, and subject both to the action of the electric 
light. Did his hearers notice the beautiful blue, like that of an Italian sky, at once 
formed in the tube? He would first explain why he mixed hydrochloric acid with the 
nitrite of butyl. When the waves of solar light beat upon the molecules of carbonic 
