ON PRUSSIATE OF POTASH. 2S5 



^t fmall diftances, with a kind of afphyxy *. It even gives 

 fume colour of probability to the ftory related by Metrodorus, 

 and preferved in the Natural Hijiory of Pliny f. 

 (To be continued,) 



viir. 



ExtraSi of a Letter from Brugnatelll on the Prujfiate of PotaJIi, 

 and on the Preparation of a fulminating Muriate of Silver. * 



If alcohol be poured into a folution of pruffiate of potafli Alcohol occa- 

 (oxipruffiate of potalbj the liquor becomes turbid, and a pre- tate^infoirt'ioli 

 cipitate is depofited in the form of fmall and very brilliant of pruffiate of 

 lamellae, refembling the fublimed boracic acid (oxiboracic.) f^g^j, fcailes"^ad! 

 Colleding this precipitate on a filter, and drying it, the fcales heringtoeach 

 adhere to one another, and form a ftratum of a (hining yellovvr- "0''^''%°,^^^'"' 

 ifli white, like that of mother-of-pearl. This mafs eafily fe- white, foluble 

 paratesfrom the filter; is foluble in fulphuric acid (oxifulphu- "^.("'pl^uric 



• » 1 .. ri . 1 1, I , , ,. • „ acid ; and this 



ric), and this lolution takes a bliie colour on the addition or folution is turn- 

 water. Expofed to the fire in a crucible, it fwells, burns, and '^^ ^^^^ ^7 

 leaves a coally refiduum, containing a great deal of iron, at- its coally refi- 

 traflable by the magnet and potaQi. This coally refiduum, d^^m contains 

 treated with acids, gave out a ftrong fraell of fulphurated hi- ma^n^etic^kon 

 drogen gas (gasphlogogcnefulfura.) andpota/hj 



and with acids 



'" fraells ftrongly 



I have applied the procefs I mentioned to you in my laft to hidrogengTsT 

 a great number of other metallic oxides (thermoxides), in hope 

 of rendering them fulminating; but I fucceeded with none, 

 except that of filver. 



Take a hundred grains of lunar cauftic (fufed oxifeptonate On 100 grains 

 of filver) in powder, put them into a beer glafs, and pour on ^^r"''"? ° d^*'' 

 them firft an ounce of alcohol, and then as much concentrated was formed firft, 

 nitrous acid (oxifeptonmux.J The mixture grows hot, enters ^^^^^^\ ' ounce, 

 into a ftate of ebullition, and an ether is vifibjy formed, that 1 ounce. 

 changes into a gas. By degrees the liquor becomes milky and As foon as the 

 opake, and is fillecj with fmall and very white clouds. When comdetely ^" 

 all the gray powder of the lunar cauftic has taken this form, formed, water 

 and the liquor has acquired a confiftency, diftUled water muft '^^l ^^T^ttdpi. 



* Hiftoire Naturelle des Serpens, p. 355. filter, 



t Lib. xxviii. cap. 14. 



t Van Mons's Journal, IV, 235. 



