1872. ] Light. 395 
by cart or railway—more expeditiously than by cart, and more securely than 
by railways. After giving a brief history of the canal, the author gave 
detailed particulars of some of the most important works undertaken in its 
construction; its capabilities for irrigation and navigation; and finally con- 
cluded by a comparison between it and the Grand Junétion Canal between 
Brentford on the Thames and Braunston. 
A paper on ‘‘ Explosive Agents applied to Industrial Purposes,’”’ was read by 
Mr. F. A. Abel, F.R.S., on the 14th of May. The nature and properties of gun- 
powder, and its special advantages and defects as an explosive agent for indus- 
trial purposes, was first briefly reviewed. The application of other compounds, 
including the use of chlorate of potash, including “ poudre picrate,”’ and those 
produced by the action of nitric acid upon organic substances, such as nitro- 
glycerine and gun-cotton, were referred to, and the two latter particularly dwelt 
upon and explained, and their advantages for blasting purposes were enume- 
rated. In conclusion, after referring to some recent interesting experiments of 
Dr. Sprengel, on the application of readily oxidisable and other powerfully oxi- 
dising liquids in the production of violently-detonating mixtures, the author 
showed that, even in the application of gunpowder to industrial purposes, 
some decided advance had lately been made, for its violent explosion could be 
developed, like that of all other explosive mixtures and compounds, through the 
agency of a detonation, whereby its action might be considerably intensified, 
and its application to some important classes of work, such as in submarine 
operations, greatly facilitated. 
Institution of Mechanical Engineers.—At a meeting of this Society on the 
2nd of May last at Birmingham, after the adjourned discussion upon a paper 
read at the last meeting, ‘“‘On the Strength and Proportions of Rivetted 
Joints, &c..” a paper was read, ‘On a Steam Jet for Exhausting Air, &c., and 
the Results of its Application,” by the President, C. W. Siemens, Esq., 
F.R.S., D.C.L. The form and application of the steam jet having remained 
hitherto essentially the same as in the original steam blast of the locomotive, 
it occurred to the author that much might be done to improve its effect by a 
judicious arrangement of the parts, so as to avoid eddies in the combined cur- 
rent of steam and air, and to utilise more completely the initial momentum of 
steam. These objects have now been effectually accomplished by the employ- 
ment of a very thin annular jet of steam, in the form of a hollow cylindrical 
column, discharged from an annular nozzle. The air to be propelled by the 
steam jet is admitted through an exterior annular orifice surrounding the jet, 
and also through the centre of the hollow jet; and the area of the air passages 
is gradually contracted on approaching the jet, whereby the velocity of motion 
of the entering air is so much accelerated, before it is brought in conta@ with 
the steam, as to avoid the great difference in the velocity of the two currents 
at the point where they come together, which caused the eddies that pre- 
viously impaired the efficiency of the steam jet. By the annular form of the 
steam jet the extent of surface contact between the steam and air is greatly 
increased, and the quantity of air delivered is by this means very much 
augmented in proportion to the quantity of steam employed. The combined 
jet of steam and air is discharged through an expanding delivery pipe of con- 
siderable length, in which its velocity is gradually reduced and its momentum 
accordingly utilised by being converted into pressure. This improved steam 
jet has been applied for exhausting one of the pneumatic despatch tubes 
employed at the Central Telegraph Station in London, for conveying the 
carriers containing telegraphic despatches from one station to another. 
Another application is to the lifting of water from a moderate depth; for 
exhausting the vacuum pans employed in sugar-boiling; and as a blower for 
accelerating the distillation of fuel in gas-producers for heating purposes. 
LIGHT. 
Mr. Harcourt has found that by heating to redness a mixture of hydrogen 
and bisulphide of carbon vapour, the latter is decomposed into sulphuretted 
hydrogen. The removal of bisulphide of carbon from coal-gas is thus 
