ARTIFICIAL REFRIGERATION AND ICE MAKING. XXXIII, 
Leslie experimented with a machine using sulphuric acid and 
water. In 1824 a machine was patented by Vallance, who 
probably got his idea from the evaporative system so long in use 
in India. Under this patent, dry air was circulated over shallow 
traysof water when evaporation took place and heat was abstracted. 
In 1858, Mr. George Bevan Sloper patented a similar system 
in this Colony,! under which the water was exposed in canvas 
bags so that the whole surface of the containing vessels was 
Open to evaporation as well as the surface of the water itself. 
The machine to work this process was designed by the author, to 
carry out the ideas of the patentee thirty-eight years ago, and it 
was constructed in Sydney by Messrs. P. N. Russell & Co., and 
tried in Margaret Street. No commercial success however did, 
or could attend any such system of producing artificial cold owing 
to the excessive amount of power required to produce a given 
result, and in this particular case, as the air delivered into the 
chamber under partial vacuum was not made to perform work, it 
did not part with its heat and reduce the temperature of the water 
as it might have been made to do had the knowledge of thermo- 
dynamics been then as widely extended as it now is. In 1834 
Hagen used the volatile spirit of caoutchouc, and in the same year 
Jacob Perkins, of London, constructed what appears to have been 
the first ice making machine which really worked successfully ° 
With a volatile liquid. In this machine ether was vaporised and 
expanded under the reduced pressure inaintained by the suction 
of a pump, and the heat abstracted from the substance to be 
cooled, the resulting vapour was compressed by the same pump 
into a vessel cooled by water until liquefaction of the medium 
again resulted as the vapour parted with heat to the condensing 
water under the influence of the increased pressure. The liquefied 
medium was then read y to be evaporated and expanded over again. 
Fig. 1 is taken from Perkins’ English patent, No. 6662 of Aug. 
1834, and shews clearly that his invention included the four 
Pe aA 
1N.S. W. L. R., No. 14, 1858. 
3—June 17, 1896, 
