458 Royal Society : — 



A portion of the powdered unchanged substance, digested sixty- 

 three days with an aqueous sokitiou of caustic potash, lost 2-95 per 

 cent, ill weight, but still retained about ^ths of its heating power. 

 A second portion, digested fifty-six days with strong hydrochloric 

 acid, lost G"GG per cent, and all its heating power. 



Exposure to light did not destroy the heating power of the 

 powdered substance. 



By depositing the gray variety of antimony into mercury, a pasty 

 compound of the two metals was formed. The amorphous variety 

 did not combine with mercury luider similar circumstances. 



An acid solution of fluoride of antimony yielded by electro-depo- 

 sition gray crystalline antimony not possessing the heating power. 



LIII. Proceedings of Learned Societies. 



ROYAL SOCIETY. 

 [Continued from p. 395.] 

 April 15, 1858. — The Lord Wrottesley, President, in the Chair. 



THE following communications were read : — 

 " On Tangential Coordinates." By the Rev, James Booth, 

 LL.D., F.R.S. 



Extract of a Letter to Admiral FitzRoy, F.R.S., from Captain Pul- 

 lenofH.M.S. 'Cyclops,' dated Aden, Tviarch 16, 1858. 



My first sounding for temperature at any depth, was in 32° 13' N., 

 long. 19° 5' W., where at 400 fathoms the minimum temperature 

 was 51°'5, the surface at the time being 70°. The water brought 

 up in the bottle was of greater density than we have since found it, 

 namely, 1031 at temp, of 70°, whilst at the surface it was 1026. 

 Supposing that you will see all the registered depths, &c. sent to 

 Captain Washington, I do not enter into full detail here. The 

 next time, I sent two thermometers down at 500 and 800 fathoms ; 

 at the greater depth, 44°'5 ; at the lesser, 50° was the minimum 

 temperature. But now I began to observe some alterations in 

 the indexes of the instruments, that of the maximum column 

 not returning to the surface in the same position in which it 

 stood on starting, viz. close to the mercury (brought to the sur- 

 face temperature by being kept sufficiently long in the water along- 

 side, and then com])ared with the deck-thermometer in constant 

 use for that observation). Now I know from former experience that 

 these indexes will shift by shaking the instrument, and with much 

 less force than is frequently communicated to it by a shake of the 

 line, on its passing up and down. From this we may infer that the 

 minimum index also moves, how much it is impossible to say. And 

 on looking over the results obtained during the voyage, I find that 

 but few of the maximum indexes have come in standing at the [)oint 

 they started with. I therefore draw your attention to the fact, that 

 such remedy may be applied as will obviate the defect. I have 

 fomid another fault in thermometers before now (but then it was at a 



