SCIENTIFIC SUMMARY. 
219 
exit as soon as they have been transformed into beat-rays. The yield of a 
large solar beat-generator is greater than that of a small one. The whole 
apparatus is arranged so as to turn 15° hourly around an axle parallel to the 
axis of the earth, and to incline gradually to this axle, according to the sun’s 
declination. An apparatus of this kind, erected at Tours, gave the fol- 
lowing results : — In ordinary fine weather, 20 litres of water at 20°, in- 
troduced into the boiler at 8.30 a.m., produced in forty minutes steam at a 
pressure of 2 atmospheres, or a heat of 121° cent. This steam rapidly rose 
to the pressure of 5 atmospheres, a limit which it was not safe to exceed. 
About mid-day, with 15 litres of water in the boiler, the steam was raised 
in fifteen minutes from 100° degrees to 153°, a pressure of five atmospheres. 
Hence the author concludes that in hot and sunny climates the sun’s rays 
may be successfully utilised as a source of mechanical power. 
A Monster Battery . — A chloride of silver battery of 3,240 elements has 
been described by Mr. "Warren De la Rue and Mr. A. W. Muller. The 
description has appeared in French, but it is thus translated in the 
“ Chemical News.” It is composed on the one part of 1,080 elements, 
each consisting of a tube of glass 15*23 c. in length, and of 2,160 elements 
formed of glass tubes of 12*75 c. in length only. All the tubes are 1*9 c. in 
diameter, and are closed with stoppers of vulcanised india-rubber, perforated 
with a^hole near the edge to permit the introduction of a rod of amalgamated 
zinc, 0*48 c. in diameter, and 10*43 c. in length for the first 1,080 elements, 
and 7*93 c. for the remainder. At the bottom of each tube powdered chloride 
of silver is placed, 14*59 grins, in weight, compressed strongly with wooden 
rods, a flattened silver wire having been first introduced to the bottom of 
the tube. The silver wires are covered in their upper part, above the 
chloride of silver, and up to the point where they emerge from the vul- 
canised stopper, with leaf gutta-percha to isolate them and preserve them 
from the action of the sulphur in the stoppers. The electromotor force of 
this battery is to that of a Daniell’s battery as 1*03 to 1. 
A Novel and Useful Form of Bunsen Burner has been described in the 
“Chemical News,” by President Henry Morton, Ph.D., of New Jersey, 
in the following terms : — “ The retreat of a burner will evidently occur 
whenever any part of the ascending column of mixed gas and air is moving 
at the orifice with a velocity less than that at which the same will bum 
downwards. Now, in an ordinary burner, with its main tube of regular 
cylindrical bore, it is evident that the friction of the surface of the ascending 
column of mixed gases will cause that portion to move at a less velocity 
than the central part, and that currents of the nature of eddies will be 
developed. It will thus happen that while the central portion of the 
ascending column of gaseous mixture issues at a velocity much greater than 
that at which the material can burn downwards, and thus is quite free from 
any danger of retreating, the marginal portions of the column or jet of gas 
will be escaping at a rate so much less that the velocity of their combustion 
downwards will exceed that of their upward motion, and retreat of the 
flame will ensue. It is well known that to secure a jet of water, or of any 
other fluid whose particles shall move with equal velocities in all parts, and 
thus avoid currents and eddies, it is only necessary to make the orifice of 
efflux an aperture in a thin wall. Following out the idea above indicated, I 
