jlpt ■ Ntw Metallic All o/.'Sihrlak Red 'Lead. 



Experiment 8.— Heated by the blow-pipe upon charcoal, it boils, and leaves^a green, iSf. 

 fufible fubftance. 



Experiment 9. — When fufed with the phofphoric glafs, or with borax,.. it communicatea^ 

 to the vitreous globules a very fine emerald green colour. ■ ! ' 



Experiment 10. — Laftly, this acid combines with alkalis and earths, from which it dif* 

 engages the carbonic acid with eflervefpence, :and forms, with thofe fubftances, falts more 

 or lefs coloured, of which the properties a^re defcribed in the following feftion. 



From the preceding refults it evidently follows, that thp min,eraHfer of the red lead ore is 

 a true acid j that the radical of this acid is a. peculiar metallic fubftance ; for no other metallic 

 acid yet known exhibits properties fimilar to the prefent. In fait. What metallic atid pof-. 

 feffes a ruby colour; com'municates to all its combinations red or yellow colours, more or; 

 lefs deep, or yields to the muriatic acid part of its oxygen, converting it into the oxygenated 

 muriatic acid, while itfelfpaffes to the ftate of a green oxide, foluble in the muriatic acidJr 

 Laftly, What metallic acid is there, which forms with merciiry. a. combination of a cinna- 

 bar red ; with filver, a carmine red compound ; with lead, an orange-yellow mineral ; with 

 the hydro-fulphuret of potafli, an olive-green,' &c.^- If I am not deceived, there is none 

 fuch. Therefore, notwithftanding the repugnance which I have to admit new fimple 

 bodies, a repugnance grounded on the numberlefs modifications which nature- may give 

 to bodies already known, and render them apparently new, I am neverthelefs forced, by. 

 the great number of new characters pofTeffed by this and by rio other fubftance, to regard, 

 it as a metal naturally acidifiied, which refembles no other we are acquainted with. 



This opinion will be ftill more confirmed by thq experiments in the following para- 

 graphs. 



SECTION VI. • 



Combimtiofii of the Acid of Red Lead ivith Alkalis, Earthsy and Metallic Oxides. : 



THE fmall quantity of native red lead which I have hitherto poffefled, has not allowed 

 me to prepare any large maffes of the falts which this acid is capable of forming with the 

 Alkaline, earthy, and metallic fubftances; in ordet to-.ex^rriine their properties with all the 

 precifion neceflary to render them perfectly known. I (hall confi-ne myfelf, therefore, in 

 this place, to exhibit their principal chara£ters, fuch as colour, folubility in water, tafte, 

 their habitudes in the' fire, ■&c. referving rnyfelf to return to this' object when circum- 

 ftances fliall be more favourable. It is well known* like wife, that a great interval of time fre- 

 quently takes place between the period when the difcovery of an uncommon fubftance ha& 

 been made, and that in which all its properties are perfedtly known, and that refearches 

 of this kind are ufually indebted to time and opportunity for their ultimate degree of 

 perfection. ; 



, Qomhination of the Acid of Red Lead -with Barytes.. 



The acid of red lead ore readily unites with barytes, with which it fdrms a fait of very 

 faring folubility ; for, by pouring an aqueous-foluiion of this acid into a folution of the 

 earth, a precipitate is formed of a pale lemon-yellow colour. This fait, however, is not 

 entirely inioluble ; for the fupernatant fluid ftill retains a flight yellow colour, though the 

 two principles of the fait are mutually faturated. This pulverulent fait has no perceptible' 



tafte; 



