j6 On the Freezing of Mercury, &c. 



ao. As fcoriaceous maffes have frequently been either 

 actually feen to fall at the time of the difappearance of thefe 

 phenomena, or have been found foon after on the furface of 

 the earth, and as it is fufficiently proved by various accounts 

 that ftones have fallen from the atmofphere, Dr. Chladni 

 concludes that both thefe phenomena are connected ; but 

 this can be determined only by future accurate ojrfervations. 



XIII. A Communication froni Mr ^N . H. Pepysj'ww. Member 

 of the London Philofophical Society, containing an Account 

 qfjbme intercjling Experiments on the Produclion of Arti- 

 ficial Cold, in one of which Fifty -fix Pounds of Mercury 

 was frozen into a folid Mafs. 

 p j ■* 



X HE freezing or fixing of mercury has been the means 

 pf, proving it to be a metal pofleffing the principal properties 

 and characteriftics ofpther metals, as fplendour, malleability, 

 and a cryftallifed ftructure when reduced to a folid form. 

 Gmelin was the firft who ever obferved mercury at fuch a 

 low temperature as leads to a belief that a partial congela- 

 tion had taken place, though he did not then fufpect the 

 fact; but " De L'lfle was probably the firft perfon upon 

 earth who fawquickfilvcr reduced to a folid form by cold, and 

 ventured to credit the teftimony of his fenfes *." This hap-» 

 pened at Yakutlk in Siberia, in 1736, where the natural 

 temperature was fo low at the time as to produce the effect 

 ■without the aid of artificial means. 



Since that period the production of artificial cold, by- 

 means of various mixtures, fumcicntly intenfe to freeze 

 mercury, has employed the abilities of the moft experienced- 

 chemiils and philofophers, as Braun, Blurnenbach, Hutch- 

 ins, Lambert Bicker, Fothergill, Cazalet, Guthrie, Caven- 



* See Dr. Blagdcn's paper on this Pjbjcft in rhe Phil. Tranfaftions for 



dilh, 



