DENSITY OF WATER,' 37^ 



• Dr. Hope alfo admits with me the fa<5l that water fubjed^ed The author and 

 t-obe cooled without agitation in a frigorific mixture, uluaily j.Jr jhafwater' 

 defcends feveral degrees below the freezing point, and ftiil may continue 

 retains its liquidity. Though it is eafy to obtain water in a fr^'j-ing^p^i!," 

 glafs bulb 20 or 2^" below freezing, I could neyer cool water 

 in an open jar more than 10 or 11** below freezing, agreeable 

 to the experience of Sir Charles Blagden. But I find water' 

 in fuch circumflances will admit of being cooled to 25^, and 

 the bulb of a thermometer to be immerfed and withdrawn fe* 

 v>eral times, without freezing.- 



We come now to the experiments of Dr. Hope. 



Experiment /. 



A jar eight Inches deep and 4| in diameter, filled with Dr. Hope'* ex- 

 water of 32^, and placed on a table, &c. Air 60— 62».P^'''™«'"1"°f*^» 

 Two thermometers inferted, one at the top, another at the 

 bottom. 



2^op Thennofueter. Bottbm Thermometet. 



Differences. Differences. 



32° - - ^ - - - . 32» 



1+ 2+ 



In 10 min. 3^-{- ------- 34-f 



2.5— 3 — 



30 35.5 --.-■--- 37 



1.5 1-h 



50 37 -------- 38-1- 



1 

 Ihour— — 38 -------- 38-^7 



'■ 4 .25-^ 



'■'1 ^0 42 ----- y - - 38.25 



2 1.75 



1 30 44 --..,.-. 40 &c: 



. In the firft- interval of 10 minutes we obferve the bottom inference that 

 thermometer to have gained 2°+, and the top only iO-|- ; the water de- 

 the former has the heat which enters dire6lly, together with "^J heat/^' 

 the heat which defcends by the fide of the veflel ; the latter 

 has only the heat which enters directly, and as thefe aire nearly 

 as one to two, we may infer that the acquifUion of diredl heat, 

 and heat by defcent, are nearly equal in the bottom tberrao-; 

 pieter during that interval. 



In the next interval of 20 miautes we obferve the bottom 

 thermometer gains 3S— , a.nd the top 2°,5 — . Here we fee 

 W:' X ' 'i? the 



