450 PHILOSOPHICAL TRANSACTIONS. [ANNO 1783. 



though it became fluid when pressed by the fingers, immediately afterwards re- 

 sumed the consistence of pap. With the thermometer at — 3g°, the quick- 

 silver became fluid. The cold was never less on the 5th than — 28°, and by g 

 in the evening it had increased again to — 33°. In the morning the wind was 

 n. n. e. and afterwards n. w." 



This experiment of M. Von Elterlein's deserves attention in many respects. 

 It ascertains the freezing point of mercury with such wonderful exactness, from 

 the melting of the solid pieces when the thermometer came up to — 3Q°, as to 

 furnish a valuable corroboration of Mr. Hutchins's experiments, and at the same 

 time very much to enhance our opinion of M. Laxmann's skill in the construc- 

 tion of instruments. When the thermometer was thought, early in the morn- 

 ing, to be standing at — 57° probably that part of the quicksilver being frozen 

 adhered in the tube. The ductility of the solid metal must have been consider- 

 able, from its yielding to the knife in the form of shavings ; yet, as in most 

 other instances, it showed some degree of brittleness when force was applied to 

 it in the mass. Crystallizing without impediment, it assumed an appearance 

 which M. Von Elterlein rather compares to that of lead than of silver. Its ten- 

 dency to adhesion became evident from the necessity of employing an instrument 

 to separate it from the tea-cup ; and its contraction in freezing was demonstrated 

 by the depression observed in the middle of the solid mass. This single experi- 

 ment therefore exemplifies, in a very beautiful manner, most of the properties 

 hitherto discovered in quicksilver, when it passes from a fluid to a solid form. 



Vytegra, or Witegorsk, is situated in lat. 6l° n. and long. 36° e. on a rive 

 of the same name. It has acquired some celebrity from one of the many useful 

 projects which occupied the active mind of Czar Peter the Great. He proposed 

 to cut a canal from the river Vytegra which discharges itself into the lake Onega, 

 to the river Kovsha which joins the Belosero, or White Lake, in order to form 

 a communication between those two great bodies of water ; but the undertaking 

 was unfortunately interrupted by his death. 



The last instance to be found of the congelation of quicksilver by natural cold, 

 occurred the beginning of the year 1782, in Iemtland, one of the northern pro- 

 vinces of Sweden. M. John Tornsten, engineer-extraordinary, is the gentle- 

 man to whom we are indebted for this observation. His letter on the subject, 

 dated from Brunflo in Iemtland, lat. 63°± N. and long. 15° e. is inserted in the 

 Swedish Transactions for 1782, together with some remarks upon it by Profes- 

 sor Wilcke. " During 12 years," says M. Tornsten, " that I have resided here 

 in Iemtland, the cold had never but once brought the thermometer so low as 

 — 36°, till the last day of December, 1781, when it fell in the evening to — 54°, 

 The following new-year's day it was sunk to — 56° at 8 in the morning, and by 

 10 to — 62°. Here it continued stationary several hours, but at half past 4 in 



