xlvi 



ing magnetically on light ; 4. Action of Magnets on the Metals generally. 

 And the twenty-first series, on new Magnetic Actions, and on the Magnetic 

 Condition of all Matter (continued) : 5. Action of Magnets on the Magnetic 

 Metals and their compounds ; 6. Action of Magnets on Air and Gases ; 

 7. General considerations. 



For the Trinity House he made a long and exact comparison of the con- 

 sumption and light of sperm and rape-oil. He gave a Friday discourse on 

 the Condition and Ventilation of the Coal-mine Goaf, and another on the 

 liquefaction and solidification of bodies usually gaseous ; another on ana- 

 static painting, and on the Artesian well in Trafalgar Square. 



Early in the year he thus wrote to Prof. Auguste De la Rive : — " I have 

 waited and waited for a result, intending to write off to you on the instant, 

 and hoping by that to give a little value to my letter, until now, when the 

 time being gone and the result not having arrived, I am in a worse condi- 

 tion than ever ; and the only value my letter can have will be in the kind- 

 ness with which you will receive it. The result I hoped for was the con- 

 densation of oxygen ; but though I have squeezed him with a pressure of 

 GO atmospheres at the temperature of 140° F. below 0°, he would not settle 

 down into the liquid or solid state ; and now, being tired and ill and obliged 

 to prepare for lectures, I must put the subject aside for a little while. 



" Nitrogen is certainly a strange body. It encourages every sort of guess 

 about its nature and will satisfy none. I have been trying to look at it in 

 the condensed state, but as yet it escapes me. 



" I thank you most truly, not only for the invitation (to the scientific 

 meeting) you have sent me, but for all the favour you would willingly show 

 me. Do you remember one hot day (I cannot tell how many years ago) 

 when I was hot and thirsty in Geneva, and you took me to your house in 

 the town and gave me a glass of water and raspberry vinegar ? That glass 

 of drink is refreshing to me still." 



Late in the year he writes to M. De la Rive : — " I have had your last 

 letter by me for several weeks intending to answer it, but absolutely 1 have 

 not been able ; for of late I have shut myself up in my laboratory and 



wrought to the exclusion of everything else I am still so involved 



in discovery that I have hardly time for my meals, and am here at Brighton 

 both to refresh and work my head at once ; and I feel that unless I had 

 been here and been careful I could not have continued my labours. The 

 consequence has been that last Monday I announced to our members at the 

 Royal Institution another discovery, of which I will give you the pith. 



" Many years ago I worked upon optical glass, and made a vitreous com- 

 pound of silica, boracic acid, and lead, which I will now call heavy glass. It 

 was this substance that enabled me first to act upon light by magnetic and 

 electric forces. Now, if a square bar of this substance, about half an inch 

 thick and two inches long, be very freely suspended between the poles of a 

 powerful horseshoe electromagnet, immediately that the magnetic force is 

 developed, the bar points, but it does not point from pole to pole, but equa- 



