1S14.] Scientific Inielligence. 235 



ance of a white thin cloud. This was bounded by a bright red 

 circle, passing insensibly into yellow. Beyond this there was a 

 very broad circular band of very faiiU blue, which terminated the 

 halo. About half past eight, the halo suddenly disappeared, and 

 the sky round the moon became quite clear. 



III. Late extraordinary Fog. 



By an anonymous gentleman, in a letter which has on it the 

 Richmond post mark, I have been favoured with the following 

 circumstance respecting the extraordinary fog, mentioned in the 

 last number of the Annals of Philosophy. " It is a very singular 

 fact, that the thick rime which settled on the trees during the fog, 

 from December 27, to January 2, was not disposed equally round 

 the twigs and boughs, but v^^as four times as deep on that side 

 which was exposed to the east, as an any other. This is particu- 

 larly remarkable, as there was no wind." 



I did not myself make this remai'k at Chelsea, where most of my 

 observations on the fog were made. Neitlier did I perceive any 

 such difference in the trees in St. James's Park. Though the 

 weather during the fog was calm, yet it is to be presumed, from 

 the coldness of the temperature, that there was a tendency in the 

 atmosphere to move from east to west. Accordingly, when it 

 began to blow in tlie beginning of January, the wind was decidedly 

 east. From the higher situation of Richmond than that of Chelsea, 

 or St. James's Park, it is probable that tlie current would be more 

 steady in the latter place, than the former. This imperceptible 

 current will serve to account for the fact adduced bv my corres- 

 pondent, while at the same time it aflbrds us a source for tl)e great 

 quantity of water deposited, which I was unable at first to account 

 for. Let us suppose the current to have moved at the rate of one 

 jnilc only in four hours, in which ease it would have been imper- 

 ceptible to us, then six atmospheres would have passed over our 

 heads in one day, and 42 atmospheres during the week that the 

 fog lasted. The possil)le deposition from such a quantity of air, 

 would have been 28 ounces on every square foot of surface, which 

 1 think, is probably more than the quantity actually deposited. 



IV. Cold produced by the Evaporation of Sulphi/rel of Carbon. 



The following Is an extract of a letter on tins interesting subject, 

 which I received from Mr. J. Murray, i'hilosopiiical Lectvncr, 

 aI)out the Cnd of January, and too late for insertion in the last 

 Number of the Annuls of Philosophy. 



" Having been lately engaged in experiments on the oxidation of 

 gold ; i had rubbed leaf gold in a glass mortar with saliva, and 

 ujxuj adding a minute jjortion of the sulphnret of carljon, again 

 began to tiiturate, when the whole bccanie a cuncrctc icy mas';. 



" A glass of water has remained on the talile since the preceding 

 evening, and though it n)ight be some degrees below Wl'-'' Pahr. it 

 indicated no disposition for congelation. A few drops of sul- 



