Oil ih& formaiion of Jce.. V1& 



Analysis. 

 Galena, when pure, has the proportion of eightj'-five lead, 

 and fifteen sulphur; but five particular specimens gave the 

 following more complex results : 



Lead 54 69 68 64 63 



Sulphur 8 16 IG 18 12 



Carbonat of lime and silex 38 15 16 18 19 



~96 loo Too Too 94 



Pyrites are frequent in lead ores, and sometimes antimo- 

 ny, copper, gold, and silver. 



Art. XXV. — Circumstances connected with the formation 

 of Ice on still ivaters, and with the continued action of 

 cold upon the fluid beneath. — Editor. 



JVew-Haven, Jan. 12, 1821. 



The recent cold weather, which, with an uniformity not 

 common in this maritime region, has prevailed with little in- 

 terruption, for nearly a month, varying between 3°* below 0, 

 and ten or twelve above — (for the coldest parts of the twen- 

 ty-four hours) has produced on our mill ponds ice of fifteen 

 inches in thickness. This ice is remarkably firm and trans- 

 parent, entirely free from intermixture of spongy portions, 

 and resembles, very much, fine masses of rock crystal, 

 with a slight cerulean tinge. 



* This is not mentioned as Die extreme cold of this climate, but only as 

 the extreme iiitherto observed by us, this winter ; this occurred at eleven 

 P. M. on the 10th inst. We have the mercury in Fahrenheit's thermome- 

 ter, occasionally dej)ressed here to 10° and 12° below 0. ' 



P. S. Jan. 20. Since the abo've note was written, the thermometer has 

 here (just before sun-rising on the 19th) indicated 12° below 0. In the in- 

 terior it has been much lower, and in Maine, as the newspapers inform us, 

 it has been 35° below 0, thus approximating to the congelation of the 

 (juicksilver. At Norwich, Conn, it has been 26° below 0. 



Jan. 25. Yesterday the thermometer sunk 5° from sun-rising till ten 

 o'clock, and was then about 0, and remained very little above through the 

 day, although the sun shone bright ; several times this winter, the maximum 

 of cold has been several hours after sun-rising. This morning, at se%-en 

 o'clock, the thermometer was 14° below — and at eleven last evening, it 

 was 9° below 0. In other exposures it was, in the morning 16°, and eveo, 

 in one instance, 17^° below — all these being greater degrees of cold than 

 were ever observed here before: and the average of the winter, thus far, is 

 colder than that of aay preceding winter on record here. Still tiierc have 

 been particular days, whose average has been colder. On the 25th, it was 2 

 o'clock P. M. before the merciirv rcse to 0, and at 3 o'clock it was 2° above. 



