19C LMINAT1NG MERCURY. 



arc mechanically impelled against the surface of the glass, the gold, 

 and tlie tallow. 



" As to the force of the dilated mercury, M. Beaume relates a 

 remarkable instance of it, as follows : 



" Un alchymiste se presenta a Mr. GeoflVoy, et 1'assura qu'il 

 avoit trouve le nioycn de fixer le mercure par une operation fort 

 simple. II fit construire six boitcs rondes en fer fort epais, quien- 

 troient les unes dans les autres ; la derniere etoit assujettie par 

 deux oerrles de fer qui se croisoient en angles droits. On avoit 

 mis quelques livres de mercure dans la capacite de la premiere ; on 

 mit cet appareil dans un fourneau assez rempli de charbon pour 

 faire rougir a blanc les boites de fer; mais, lorsqm- la chaleur eut 

 penetre suflisamment, le mercure, les boites creverent, avec une 

 telle explosion qu'il se fit un bruit epouvantable ; des morceaux de 

 boites furcnt lances avec tant de rapidite qu'il y en eut qui passe, 

 rent au travers de deux planchers ; d'autres firent sur la muraille 

 des effets semblables a ceux des eclats de bombes*." 



*' Had the alchemist proposed to fix water by the same appa. 

 ratus, the nest of boxes must, I suppose, have likewise been rup- 

 tured ; yet it does not follow that the explosion would have been 

 so tremendous ; indeed, it is probable that it would not, for if (as 

 Mr. Kirwan remarked to me) substances which have the greatest 

 specific gravity have likewise the greatest attraction of cohesion, 

 the supposition that the vapour of water, would agree with a posi. 

 tion of Sir Isaac Newton, that those particles recede from one 

 another with the greatest force, and are most difficultly brought to- 

 gether, which upon contact cohere most strongly. 



" Before I attempt to investigate the constituent principles of 

 this powder, it will be proper to describe the process and manipu- 

 lations which, from frequent trials, seem to be best calculated to 

 produce it. One hundred grains, or a greater proportional quan. 

 tity of quicksilver, (not exceeding 500 grains), are to be dissolved, 

 with heat, in a measured ounce and a half of nitric acid. This solu- 

 tion being poured cold upon two measured ounces of alcohol, previ- 

 ously introduced into any convenient glass vessel, a moderate heat 

 is to be applied until an effervescence is excited. A white fume then 

 begins to undulate on the surface of the liquor ; and the powder 

 will be gradually precipitated, upon the cessation of action and re. 



* Chymie E*primentale et Raisonn6, torn. ii. p. 59"?. 



