188 Dr. Gobel o)i Molybdate of Lead, 



plumbane is a compound of 100 lead +35 chlorine; there- 

 fore the above 72*5 grs. of plumbane contain 5^'9 of lead, 

 which combined with oxygen makes 59'0 oxide of lead. 



III. — The fluid separated from the chloride of lead was 

 now evaporated to drjTiess ; and nitric acid was poured over 

 the residuum, which produced by its decomposition a strong 

 effervescence and evolution of nitrous gas; and the blue 

 molybdous acid became again a yellowish-white powder (mo- 

 lybdic acid), which, when dried by evaporation and ignited in 

 a coated crucible, weighed iO'S grs. 



According to this analysis, 100 grs. of the yellow lead ore 

 consist of Oxide of lead ... 59*0 



Molybdic acid... 40-5 



Loss 00-5 



100-0 

 The component parts, reckoned according to their propor- 

 tions, correspond nearly to 1 proportion of molybdate of lead ; 

 and the regularly crystallized yellow ore is to be looked upon 

 as such. It therefore consists of 



One proportion of oxide of lead =107*5 

 One proportion of molybdic acid = 77*5 



185-0 

 Taking a centesimal division, we have 

 Oxide of lead 58*1 

 Molybdic acid 4 1-8 

 99-9 

 According to Klaproth, it consists of 



Oxide of lead 64-42 

 Molybdic acid 34-25* 



98-67 

 B. Tartarus Stibiatus. 

 Some very fine and large regular crystals of this salt in- 

 duced me to examine them ; the result I obtained is given be- 

 low. The crystals were about one inch long, and half an inch 

 in diameter, and were very fine and transparent double four- 

 sided pyramids. 



* Although the results of Dr. Gobel's analysis of molybdate of lead differ 

 so materially from those obtained by Klaproth, yet they nearly agree with 

 Mr. Hatchett's, which were as follows : 



Oxide of lead 58-40 



Molybdic acid 38-00 



Oxide of iron 2-08 



Silica 0-28 



Loss 1-24 



10000 

 Sec Phil. Trans, for 1 796, p. 323.— Edit . 



I foiind 



