Expcyiineiils on Fulminating Silver, 297 



A defcription was given of many other fpecimens which had been inadvertently exploded 

 and Joft ; fome by overheating them to about go°, in the place where they vi ere to be dried ; 

 and others by an accidental concuffion of a great iron plate, on which they were placed in 

 leparate cups. 



The experimenter faid, that he had often exploded fulminating filver, in covered vefTels 

 of the fmalleft capacity that could be ufed with fafety; and that this fubftance had frequently 

 exploded unexpefledly in his hand, with a report louder than that of a mufket. 



A luminous and momentary gleam was always vifible, but he could not difcover any other 

 adequate effeft of the emitted caloric ; and therefore he concluded, that in fuch inflantaneous 

 explofions the caloric was expelled with velocity fuiTicicnt to conftitute light. 



Mr. Berthollet, the inventor of fulminating filver, having contented himfelf with a general 

 and concife defcription of this fubjeft, many praftical chemifts have failed in their attempts 

 to prepare it; and others, forming their opinions from the fpecimens which they had made, 

 have been expofed to great danger ; as will appear from the following relation, which is the 

 only part of the Minutes on this fubje£l that can be introduced in the prefent publication. 



An ounce of fine filver was diflblvcd in the courfe of eight hours in an ounce of pure 

 nitrous acid, of the London Pharmacopoeia, diluted previoufly with three ounces of diftillcd 

 water, in a glafs matrafs. The folution being poured off, the refiduary black powder and 

 the matrafs were waflicd with feveii or eight ounces of warm diftilled water, and this was 

 added to the folution. The black powder being gold was rejected ; fome gold being thus 

 feparable from any filver of commerce. 



To the foregoing diluted folution, pure lime-water prepared with diftilled water was 

 tidded gradually, for the folution ought not to be poured into the lime-water. When about 

 thirty pints of lime-water had been expended, and the precipitate had fubfided, more lime- 

 water was added, by fucceflive pints, as long as it caufed any precipitatiorh For it was 

 •deemed fitter that the precipitation (hould not be pcrfe£led, than that an excefs of lime- 

 water fliould be ufed ; the earthy pellicle of the excefiive lime-water being apt to mix with 

 the precipitate. The clear liquor being poured away, the precipitate was poured off, and 

 wafhed into a filter. 



When the falinc liquor had drained from it, two ounces of diftilled water were poured oa 

 the magma ; and when this water had pafled, frefh- portions were fucceflively added and 

 pafled, until the whole quantity of w;ater thus expended in waftiing away the nitrous cal- 

 careous fait amounted to a quart. 



The filter being then unfolded, to let the magma of oxide of filver fpread on the flattened 

 paper, it was placed on a chalk-ftone to accelerate the exficcation, and was gradually dried 

 in the open air ; a cap of paper being placed loofely over it to exclude the duft. 



When the weather fcrved, the cap was removed, to c.vpofe the oxide to tlic rays' of the 

 fun; although this was not deemed ncccll'ary ; and the exficcation was promoted by cutting 

 the oxide into thin fliccs. When perfc£lly dry it weighed I 07.. 4 dwts. and about one-fifth 

 of it Wt-vs confidered as oxygcnc. 



" When aqua ammoniie pura; of any PhaTmncopoeia is ufed with this oxide, either in 

 the fmall quantity which blackens ir completely, or in a greater quantity ; the black matter . 

 which fubfidcs, and which has been reprcfonted by fyllcmatlc writers as ihc fulminating 



Vol. I. — OcTOBtH 1797. C>^q compound, 



