550 PHILOSOPHICAL TRANSACTIONS. [aNNO 17(5I, 



mined; and hence arises no small difficulty in determining its specific gravity, as 

 this last must increase, as the bulk of the mercury lessens. Hence as mercury, 

 even in its fluid state, comes of all bodies, platina excepted, the nearest to gold ; 

 in its solid state, it must still approach much nearer. 



Our author had 3 thermometers filled with the most highly rectified spirit of 

 wine. These not only corresponded exactly with each other, but, in less severe 

 trials, corresponded reasonably well with those filled with mercury. But by the 

 mixture of snow and spirit of nitre, which froze the mercury, he never was able to 

 bring the spirit thermometers lower than 300. Hence it appears, that the heat 

 which will freeze mercury, will not freeze spirit of wine , and that therefore spirit 

 thermometers are the most fit to determine the degree of coldness in frigorific 

 mixtures, until "we are in a situation to construct solid metallic thennometers with 

 sufficient accuracy. He made many experiments to try the effects of different 

 fluids in his frigorific mixtures. He invariably found, that Glauber's spirit of 

 nitre and double aquafortis were the most powerful. With oil of vitriol, the most 

 onderous of all acids, he was never able to congeal mercury. He likewise tried 

 a great number of other fluids, both acid and spirituous, which though, when 

 mixed with snow, produced cold, it was in very different degrees. He tried a 

 series of experiments to this purpose ; but it was in weather far less cold than the 

 preceding experiments were tried in, viz. between 159 ^'^"d 153, by his thermom- 

 eter. By these it appears, that spirit of salt pounded on snow, increased the 

 natural cold 30 degrees; spirit of sal ammoniac, 10; oil of vitriol, 35 ; Glauber's 

 spirit of nitre, 58 ; aquafortis, 40 ; simple spirit of nitre, 30 ; spirit of vinegar, 

 and lemon juice, made no remarkable difference ; dulcified spirit of vitriol, 20 ; 

 Huffman's liquor anodynus, 32 ; spirit of hartshorn, 10; spirit of sulphur, 10; 

 spirit of wine rectified, 20 ; camphorated spirit, 1 5 ; French brandy, 1 2 ; and 

 even several kinds of wine, increased the natural cold to 6, 7j or 8 degrees. That 

 inflammable spirits should produce cold, seems very extraordinary, as rectified 

 spirit seems to be liquid fire itself; and what still appears more paradoxical is, 

 that inflammable spirits poured into water, cause heat ; upon snow, cold : and what 

 is water but melted snow ? 



Though not immediately relating to the principal purpose of this treatise, our 

 author measured by his thermometer, when it stood in his study at 128 degrees, 

 the heat occasioned by pouring difterent fluids into water. He found, that oil of 

 vitriol produced 35 degrees ; spirit of sea salt, 10 ; Huffinan's anodyne liquor 

 rectified, 5 ; spirit of wine, 10. On the contrary, spirit of sal ammoniac mixed 

 with snow, spirit of sulphur, and spirit of hartshorn, mixed likewise with snow, 

 made no perceptible diflerence. Highly rectified chymical oils, mixed with water, 

 produced no heat ; nor with snow, no cold , as was tried in the oils of turpentine 

 amber, mint, and mother of thyme. And here it is to be remarked, notwithstand- 



