2 1)6 Fiilminnting Gold and Silvef. 



longer than apples and pears; but thefe are kfs watery, and I believe the vclTcls in which 

 their fluids are contained are fmaller : and both thefe circumftances ought, according to 

 oi'.r afTumed principles, to render the paflage of their heat out of them more difficult, and 

 confeqviently to retard their congelation. 



[To be ccntinuid.'] 



II. 



Expeiimciils and Ohfcrvat'ions on tlefulmbialing Preparations of Gold and Silver *. 



i H E betl procefs for the preparation of fulminating gold being fliewn ; the principles 

 furnifiied by the acids during the folution of the gold, and thofe furnirtied by the ammoniac 

 during the precipitation, and the order neceflary in the application of tl em, were con- 

 fidered, and divers experiments were related, by which it appeared that this fubllance con- 

 fitls of oxvgen, azote and hydrogen feverally combined with caloric, and feverally attached 

 to the gold as a common bafe. 



Twelve grains of this fulminating gold being placed in a conical heap on a thin plate of 

 brafs, were gradually heated. At a temperature between 300 and 400", the whole exploded, 

 with a very (harp and loud report, and the plate was pierced and torn. The round aperture 

 was about an inch in diameter, and the lacerations extended much farther. 



It was obfcrved that the fame efiedl might be produced by applying a fpark to fulminating 

 gold Icfs heated, and that the accenfion of all fuch fulminating compounds, by a fpark ap- 

 plied to any part, or by due augmentation of the temperature of the whole, is eafily expli- 

 cable on the grounds mentioned in the minutes of the laft meeting, provided due attention 

 be paid to the ftate of the aclive ingredients. 



In fulminating gold, for inftance, the attraflive powers tending to produce the new com- 

 binations, v.hich take place in the inflant of combuflion, fecm to be almoft equal to thofe by 

 which the aggregation of this compound is maintained at low temperatures. For a fmall 

 augmentation of temperature, or friiflion, or percufTion, or any thing which difturbs the ar- 

 rangement of the gafeous principles and caloric which adhere but weakly to the gold, is fuf- 

 ficient for the explofion of the whole, provided the fulminating gold be pure and dry. 



In refpe£l to the perforation of the brafs plate, it was obfcrved that all bodies which ex- 

 plode inftantaneoudy would imprefs it in a fimilar manner. For the refiflance of the air to 

 projectiles or to cxpanfions of this kind, being in the ratio of the fquares of the velocities of 

 the moving or expanding bodies, the refinance of tl'.e air to fuch inflantaneous explofions as 

 thofe lately mentioned, is almoft equal to that of a folid, or of the metallic plate on which 

 tlie fulminating body is heated. 



SMALL portions of fulminating filver, each weighing lefs than a grain, were fucccffively 

 ' exploded, fome by the touch of a fiendcr brafs wire, others by that of a feather. 



■ Fiom the Minutes of .i Society for Pliilofopl.ical Experiments an'i Communicaiions : B. Hijjgins, M. D. 

 Opcramr. 1 do not hear thu the I'ocitty is continued fmcc the Jep;irtuic of ihc able Operator for the V\'efl- 

 InJics. N. 



A defcrip- 



