22 PHILOSOPHICAL TRANSACXrONS. [aNN0 1724. 



At 6'' 40"" 23Mhe beginning, doubtful; apparent time. 

 37 the total immersion of the moon. 

 50 the beginning of the emersion. 

 42 the end of the eclipse. 



Experiments and Observations on the Freezing of Water in Vacuo. By M. 

 Fahrenheit. N° 382, p. 78. Abridged from the Latin. 



Among the several surprising phsenomena of nature, M. Fahrenheit always 

 thought the freezing of water not the least considerable; hence he was often 

 desirous of trying what would be the effects of cold, on including water in 

 vacuo; and because the 2d, 3d, and 4th of March, 1721, O. S. were favour- 

 able for that purpose, he made the following experiments and observations. 



Before he comes to the experiments themselves, he premises some things on 

 his thermometers, the division of the scale, and his method of exhausting 

 them. His thermometers were chiefly of two sorts; one filled with spirits of 

 wine, the other with mercury ; and their lengths were different, according to 

 the uses they were designed for; but they all agreed in having the same nun)ber 

 of degrees, and in the fixed limits of their variations. The scale of thermo- 

 meters for meteorological observations only, begins below at O, and ends at 96 

 degrees. There are three fixed limits in this division; tlie first is in the lowest 

 part or beginning of the scale, and produced by the commixture of ice, water, 

 and sal-ammoniac, or even sea salt; if into this mixture the thermometer be 

 put, it descends to O. This experiment succeeds better in winter than in 

 summer. The second limit is when water and ice are mixed together without 

 the abovementioned salts; for putting the thermometer into this mixture, it is 

 at 32 degrees, which M. Fahrenheit calls the limit of initial congelation; for 

 stagnant waters are covered with a thin crust of ice in winter, when the ther- 

 mometer is at that degree. The third limit is at the 96th degree, to which the 

 spirits are dilated, while the thermometer is held in the mouth or under the arm- 

 pits of a healthful person, till it perfectly have acquired the same degree of heat 

 with the body. The scale of the thermometers for determining the degrees of 

 heat in boiling liquors, also begins at O, and contains 600 degrees; for, the 

 mercury itself, with which the thermometer is tilled, begins to boil at about the 

 same degree. 



That the thermometers may be the sooner affected with all the changes of 

 heat, they are provided with glass cylinders, instead of balls; for, by reason of 

 the greater quantity of superficies, they are sooner penetrated by the different 

 degrees of heat. 



