BY J. W. SUTTON, XVII. 



increase the voluaie of gas by an amount equal to the original 

 bulk, a similar decrease in the original volume would require a 

 reduction of the temperature to tilS" Cent, below zero, or equal 

 to iod'^ balow ice temperature, Fahrenheit, which is agreed to 

 be the real absolute zero. This is not a creation of the imagina- 

 tion by any means, a gas exists in that particular state owing to 

 the molecules causing vibrations — more heat more rapid the 

 vibrations, less heat less vibrations, no heat no vibrations, the 

 point to which a gas can be cooled, until it can shrink in volume 

 no further. When Fahrenheit devised the scale of our ordinary 

 thermometer in 1714 he appears to have concluded that a mix- 

 ture of chloride of ammodia and snow, produced the most in- 

 tense cooling effect possible, and so named the temperature thus 

 obtained zero, bat observations prove that in Siberia it might 

 fall to OO'^ below this preconceived lowest point, while the 

 mercury of the original Fahrenheit thermometer would freeze 

 at 39'^ below zero. Alcohol was afterwards used for low tempera- 

 ture recording, so that recent discoveries clearly point out that 

 the real zero mist be placed very much lower down the scale. 

 The thermometers used in recording these low temperatures are 

 the platinum resistance, based on the curious effect of intense 

 cold increasing the condactivity of the metal. 



Liquid air, of which we have heard so much of late, 

 ani the revolution it is to play in the near future as a motive 

 power and powerful explosive, has yet to be brought within the 

 limits of commercial success and usefulness. A power that may be 

 obtained at next to no cost, must be taken with the proverbial 

 grain of salt, and looked upon in the light of the Keely motor. 

 Still there is no doubt that there is a large and useful sphere 

 op3n to it, owing to its great expinsive pow^r, being 800 times 

 its own volume, and the material to be had tor the taking, and 

 at the present time a large amount of machinery is being 

 erected, to supply this article for cold storage and other purposes, 

 for which it is propose! to supply it at 9d. per gallon, with possible 

 reductions to half that amount. Thus we have that which was 

 only a short time back a chemical curiosity of the laboratory 

 produced only by the drops, followed by larger quantities avail- 

 able for experimental purposes, and now we have the announce- 

 ments among the articles of the month, of the completion of 

 commercial plants to supply thousands of gallons per day. The 

 story of liquid air is but a repletion of that of aluminium, and 



