276 History of Luminescence 



light was due to the friction of the mercury against the glass, but 

 did not profit by the suggestion. 



Discussion of the barometer light had actually stimulated Hauke- 

 bee (1705) to undertake his own experiments on the light from 

 mercury in motion and from friction on surfaces, together with his 

 observation on light in vacuo. However, he worked with large 

 vessels rather than barometer tubes. Hauksbee discussed and for 

 all practical purposes demonstrated the electrical origin of the mer- 

 curial phosphor, although it remained for Christian Ludolff (1710- 

 1763) actually to test a barometer in 1745 and find by the move- 

 ment of silk threads that the glass became electrified in the region 

 where the mercury had passed. The manner in which light and 

 electricity came to be closely associated will be explained in the 

 following sections. 



FRANCIS HAUKSBEE AND EVACUATED GLOBES 



In the meantime a worthy successor to Robert Hooke was ap- 

 pointed to prepare experiments for the Royal Society, Francis 

 Hauksbee (died 1713) , about whose life little is known except that 

 he had no formal education. One of his many interests was the 

 mercurial phosphor, which he imitated ^^ with a mass of mercury in 

 an evacuated bottle. The demonstration led him to publish several 

 papers in the Phil. Trans, between 1705 and 1711, having to do with 

 the light which appears when bodies are rubbed or abraded in a 

 vacuum. This work, with additional material, which was collected 

 in a book, Physico-mechanical Experiments, London, 1709, entitles 

 Hauksbee to be called the founder of the science of electrolumi- 

 nescence, even though von Guericke had noticed the " lighting 

 virtue " of his sulphur sphere when rubbed. A second edition 

 (1719) contains two additional experiments on light, but nothing 

 new was added to his previous discoveries. The title page of the 

 first edition is reproduced as figure 23. 



Hauksbee first described what happens when air is passed through 

 mercury into a vacuum, " blowing up with Violence against the 

 sides of the glass that held it, appearing all-round as a body of Fire, 

 made up of abundance of glowing Globules, Descending again into 

 its self. The Phenomenon continuing till the Receiver was half 

 Repleat with Air." 



In another experiment mercury forced into an evacuated vessel 

 by the pressure of the air appeared " like a Shower of Fire in a 



''F. Hauksbee, Phil. Trans. 24:2129-2135, 1704-1705. Most laboratory workers have 

 seen the greenish glow at the region where mercury vapor condenses in a mercury 

 vacuum pump. 



