aoo On a new fulminating Mercury. 



decanters containing the two earths to be examined ; the rife or deprefRon of the liquoi 

 will indicate which has the greateft abforbent power, and the meafure of its excefs. I 

 conftrufted fuch an inftrument, but have not yet pulhed the inquiry to any extent. 



Before I conclude, I muft notify that the deficcating quality of flannel may be employed 

 for the graduation of the hygrometer, inftead of that of the fulphuric acid. A large piece 

 of flannel dried well at a fire, laid between the leaves of a book to cool, and then placed 

 in folds within a large receiver, will produce a drynefs of 80° at the temperature of 16°. 

 Thofe, however, who wi(h to purchafe the hygrometer or photometer, may apply to Mr. 

 Cary, optician, in the Strand. 



JOHN LESLIE. 

 Largo, Fife/lnre, June 9, 1 800. 



III. 



On a New Fulminating Mercury. By EawAltD Howard, Efq. F.R.S. 

 [Continued from page 178.) 



H- 



. AD the alchemift propofed to fix water by the fame apparatus, the neft of boxes muft, 

 I fuppofe, have likewife been ruptured ; yet it does not follow that the explofion would 

 have been fo tremendous : indeed it is probable that it would not, for if (as Mr. Kirwan 

 remarked to me) fubftances which have the greateft fpecific gravity, have likewife the 

 greateft attra£lion of cohefion, the fuppofition that the vapour of mercury exceeds in ex- 

 panfive force the vapour of water, would agree with a pofition of Sir Ifaac Newton, that 

 thofe particles recede from one another -with the greatejl force, and are tnoft difficultly brought 

 together, -which upon contact cohere mojljlrongly *. 



SECTION IX. 



Before I attempt to inveftigate the conftituent principles of this powder, it will be pro- 

 per to defcribe the procefs and manipulations which, from frequent trials, feem to me beft 

 calculated to produce it. 



100 grains, or a greater proportional quantity, of quickfilver (not exceeding 500 grains t) 

 are to be diflblved, with heat, in a meafured ounce and a half of nitric acid J. This folu- 

 tion being poured cold upon two meafured ounces of alcohol §, previoiifly introduced into 



• Newton's Optics, p. 372, 4th EJ. Lond. 1730. 



■f- The reafon of this limitation is not on account of any danger attending the procefs; but becaufe the 

 quantities of nitric acid and alcohol required for more than 500 grains, would excite a degree of heat 

 detrimental to the preparation. 



J Of the fpecific gravity of about 1,3. 

 § Of the fpecific gravity of about ,84.9, 



any 

 4 



