COXe’s TRAVELS IN RUSSIA.

693

and other gentlemen. I inferted the mercurial thermometer ufed in the laft experimentin a portion of the purified mercury, N’t, and placed them in the cold mixture : thethermometer fell flowly to twenty-two and a half degrees, and was ftationarv fome time,whilft we perceived the mercury in the tube freezing round the fides, fo as to producea coating like tin foil in the Leyden phial ; on tranfporting it to a fecond glafs of coldmixture, the thermometer fell in five minutes to thirty-fix degrees, where it remainedftationary during the time of its continuance in the mixture. What was remarkable inthis experiment, the mercury in the thermometer was dill fluid, although its bulb wasfrozen into that contained in the tube ; for on reverfing the inftrument, the mercuryran out of the bulb into the ftem. Now, here is a proof that mercury may be cooledthree and a half'degrees below its freezing point without becoming folid.

“ Third experiment with native mercury.—It having been afferted, that a thermome-ter, filled with highly rectified fpirits of wine, is better calculated to determine the freez-ing point ot mercury, than one filled with the fame metal, becaufe it refills congelationlonger, I plunged the fpirit thermometer into the tube containing the native mercury.Having placed the apparatus m the glafs witn the refrigerant mixture for five minutes,and tranfported it into a fecond glafs, theipirit falling in the thermometer to thirty-two,we examined the mercury, and found it frozen, although the fpirits of wine remainedfluid, and the thermometer flood at the fame degree, (not only while the apparatus re-mained in the cold mixture, but even after I tranfported it into a warm room) and keptit at the fame point, until a large part of the buib of the thermometer was uncoveredby the melting of the frozen mercury, drop by drop, into a glafs.

“ Fourth experiment on common barometer mercury.—The mercurial thermometerufed in the firft experiment was plunged into this mercury, and placed in the glafs ofcold mixture, and after remaining five minutes, was tranfported into a fecond glafs, wherein four minutes the thermometer funk to thirty-eight, and remained ftationary. Thefame Angular phenomenon prefented itfelf that appeared in the fecond experiment,with fome additions; viz. the mercury fubfided to five and a half degrees below its freez-ing point on this thermometer, without becoming folid.

“ Fifth experiment with the fame mercury.—I froze a little of this mercury, withoutinferring a thermometer, in order to try its malleability and fpecific gravity ; it flattenedunder the hammer, and of courfe is malleable, and funk in fluid mercury, which (hewsthat it contra&s confiderably in freezing, differing in this circumftance from commonice, which expands and fwims in water.

“ Sixth experiment on mercury adulterated with tin.—The fpirit thermometerbeing plunged into this mercury, flood at thirty-two when the mercury was frozen roundits bulb.

“ Seventh experiment on purified mercury, was on the ioth of January 1785 (a re-petition of a former one) in the prefence of Profeffors Pallas and Ferber, and other gen-tlemen. I plunged the fpirit thermometer into a portion of Winterberger’s vivifiedmercury, and it fell to 32 degrees below.o, whilft the mercury was freezing, and re-mained there after it became folid fo long as it flood in the frigorific mixture. I thendrew the thermometer out of the tube with its bulb froze into the mercury, and hungit on a nail in the open air; the metal melted flowly in drops, and the fpirit flill kept atthe fame point until the greater part was thawed. We finifhed thefe experiments bytrying with the fpirit thermometer, what degree of cold was produced by a freflt frigo-rific mixture, which appeared to be juft 35 degrees below o.

“ From the whole of thefe experiments, I am difpofed to conclude, that the freezingpoint of mercury is at 32 degrees below o on Reaumur’s thermometer, or 40 of

Fahrenheit,