SCIENTIFIC SUMMARY. 
231 
in tlie inside of tlie vessel, and lap over tlie edges, not only for protecting 
tlie ragged edges of tlie glass, but to prevent the bubbles from bursting.. 
The carbonic acid used should be passed through a wash-bottle containing 
potassic carbonate, so as to free it from the vapour of hydrochloric acid, and 
then conducted into the cubic vessel until it is quite full. If a bubble now 
be blown with the glycerine and soap solution it may be floated easily on 
the carbonic acid. Should a draught carry it to the side of the vessel the 
strip of cloth will cause it to rebound again to the centre, and thus the 
bubble may float for many seconds, or even for a minute or two. — Vide 
Chemical Neios, Vo. 419, 
Diffusion of Liquids and Gases. — In one of last year’s numbers of the Journal 
fur Praktisclie Chemie, Herr Merz describes a most instructive and pleasing 
experiment, by w^hich the principle of diffusion may be illustrated. A por- 
tion of the shell of an egg having been removed by the action of hydrochloric 
acid, leaving the membrane exposed, the egg is to be suspended in water 
from the arm of a balance, a counterpoise being placed in the opposite scale. 
In about half an hour the weight of the egg has sensibly increased, as the 
position of the balance-beam will show, in consequence of the passage of 
water through the membrane. If, now, alcohol be sub.stituted for the w^ater, 
and the weights readjusted so as to bring the beam horizontal, it will soon 
commence to move in the opposite direction, showing that the egg has 
become lighter by the diffusion of water into the alcohol. The diffusion of 
vapour may be exhibited by tying a diaphragm of india-rubber — a portion 
of a small toy balloon will answer the purpose — over the mouth of a funnel, 
the other end being in communication, by means of an elastic tube, with a 
vessel of water. The f^nel being inverted over a dish containing ether, 
Avhich, however, the diaphragm is not to touch, the vapour of this fluid will 
pass rapidly into the funnel, the air being observed to escape in bubbles in 
the water at the small end. Hemove now the vessel of ether, and the 
operation will be reversed, the vapour passing through the diaphragm into 
the atmosphere. In order to fill the vacuum thus created the water will 
rise in the tube, the lower part of which should be of glass to render this 
apparent, and the diaphragm will be curved inwards. These experiments 
are particularly instructive, and are within reach of every one. The balance 
may be extemporised by means of a light bar of wood. 
Scientific Memoirs. — All workers have felt the disadvantages of the absence 
of anything like a satisfactory physical bibliography, such as the zoologists 
possess in Cams’ excellent book. They will be glad, therefore, to learn 
that the first volume of the Catalogue of Scientific Papers, which has been in 
preparation for a long time by a committee of the Royal Society, has been 
published. It is a 4to volume of about 1000 pages, and includes the titles 
of papers and authors’ names from A to Clu. The second volume also 
approaches completion. 
Registration of Earth- Currents of Electricity . — The earth-currents which 
are frequently such a source of annoyance to the workers in telegraphic 
offices have been recently investigated by Professor Airey, who has devised 
a combination of the galvanometer and photography, by means of which 
their currents are registered. Professor Airey’s paper was read at a very 
recent meeting of the Royal Society. 
