282 On the rrenO Metal called ChrSme 



quantity of the combination of the acid of red lead with pot-» 

 -afh, and I obtained ^3 grains, or about 2.282 grammes of 

 red lead, as beautiful as the natural mineral. The other 

 portion of the nitrate of lead, precipitated by cauftic potafh., 

 gave 28 grains of the white oxyde of lead. Thus, by this 

 fynthefis, j oz parts of red lead would be compofed of 65. J 2 

 of the oxy'e of lead and 34.88 of acid. By ai^alyhs, as 

 has been {hewn, it gives only 1.72* lefs in the acid which 

 mineralifes the red lead — a difference which approaches as 

 near to c ;rrech-.efs as chemical means will admit f. 



Though the properties above (hewn were more than fuffi- 

 eienr, ftrictly fpeaking, to convince any one well acquainted 

 with the differential characters of metallic fubftances, that 

 the one in queftion belongs to a particular fpecies, I thought 

 it my duty to compare its acid by a feries of combinations 

 with the molybdic acid, in fome properties of which it 

 feems to partake. 



Comparative Experiments on the Molybdic Jcid and that of 

 Red Lead. The Combination of the former with Potafh is 

 dfitruljhed by the Letter A, and the Combination of the lat* 

 tcr with Pota/h by the Letter B. 



The combination of "the molybdic acid with potafh fur- 

 nifhes a fait which has no colour. 



The combination of the acid of red lead with potafh 

 gives a fait of an orange colour. 



A, Mixed with filings of tin and the muriatic acid, imme- 

 diately becomes blue, and precipitates flakes of the fame 



* There muft be a rnift kc in fdrne of the cyphers; for the difference 

 between 36.4 given by analyfis, and 34.83 obtafaed by fynthefis, is only 

 1.52. EniT. 



t It is known bv the experiments of C Marquirt, that the red lead 

 of Siberia contains a tV.iall quantity of the water of cryftallifation, which 

 amounts to threje or four centiemes. It may be poiiible, therefore, that 

 this difference may bt owing to that ftibftance. 



colour, 



