hy Artificial Cold. 79 



have been about two minutes ; but the accident that hap- 

 pened to my hand prevented me from noting it exactly. On 

 trying the temperature of the mixture, I now found it — 42 -: 

 the addition of fome fnow, which had been cooled for the 

 purpofe while the preceding experiment was going on, re- 

 duced it again to — 50 . 



We now put into the mixture a glafs tube containing 

 fome mercury. In two minutes it was completely fixed. 

 We broke the tube, and bent the cylindrical piece of mer- 

 cury into an acute angle, by means of pincers : we attempted 

 to flraiten it again, but it became fluid during the operation. 



Several fubftances in proper veffels were now tried in the 

 cold mixture. Sulphuric ether exhibited no figns of con- 

 gelation : rectified fpirit of turpentine became thick and 

 nearly confident at — 50°: pure concentrated fulphurieacid 

 was fixed: acetic acid likewife was fixed ; nitric acid became 

 thick and ropy. On muriatic acid the cold bad no effect. ■ 



On the 7th of this month (Feb.) we repeated our expe- 

 riment, in the prefence of a number of our acquaintance^ 

 with the fame fuccefs as before. 



Encouraged by the fuccefs of thefe experiments, we re- 

 folved to attempt one of fome magnitude. Accordingly, oa 

 the following day, my friend Allen, who is a zealous and 

 able chemift, ftarted a bullion of mercury for the purpofe j 

 and, having weighed 56 lbs. avoirdupoife, we prepared every 

 thing neceffary for fixing this quantity. 



The mercury was put into a ftrong bladder and well fe- 

 cured at the mouth, the temperature of the laboratory at the 

 time being + 33°. A mixture confiffing of muriat of lime 

 2 lib. at -+- 33 and the fame weight of mow at -f- 32 gave 

 — 42°. The mercury was put as gently as poffible into this 

 mixture (to prevent a rupture of the bladder), by means of 

 a cloth held at the four corners. When the cold mixture 

 had robbed the mercury of fo much of its heat as to have its 

 own temperature thereby raifed trom - 42 to + 5, another 

 mixture, the fame in every refpect as the lail, was made, 



which 



