Dr. Tho7nas Andrews : The Great Chemist 123 



physicists and deserves to be remembered on the roll of our 

 countrymen. 



The only other research of Professor Andrews' which I shall 

 mention is his great investigation which resulted in the Bakerian 

 lectures of 1869 and 1876, on the "Continuity of the Liquid and 

 Gaseous States." 



A hundred years ago Caignard de La Tour heated a number 

 of volatile liquids in sealed tubes, and noticed that, at a temperature 

 which seemed fixed for each liquid, the meniscus of the surface 

 gradually flattened out, and then, somewhat suddenly, the tube 

 became filled with homogeneous matter. In 1826 Faraday 

 succeeded in liquifying Chlorine, rather unexpectedly it must 

 be admitted. He was then assistant to Davy, and was ex- 

 perimenting at his desire on several substances. He had sealed 

 into a bent glass tube a small quantity of Hydrate of Chlorine 

 Crystals, which are formed by exposing moist Chlorine gas to 

 a temperature of 0°C. You will remember that it was Davy 

 who proved that Chlorine was an element. When Faraday gently 

 heated the crystals in one end of the bent tube some drops 

 of an oily looking yellow liquid condensed in the other, the cool 

 end. Of course the generation of the chlorine had greatly 

 increased the pressure in the tube and caused partial liquefaction. 

 There is a pleasant story to the effect that Dr. Paris entered the 

 laboratory while this experiment was in progress, and after seeing 

 the yellow drops scolded the worker for his carelessness in allowing 

 the materials to be contaminated. Faraday answered nothing at 

 the time, but the next morning Dr. Paris received a short letter 

 reading — 



"Your oily drops were nothing but Liquid Chlorine." 



Michael Faraday. 



In these experiments Faraday succeeded in liquefying a 

 number of gases. He returned to the subject in 1845, when, 

 by the joint application of pressure and cold he eflfected the 

 liquefaction of a further number. He published the opinion that 



