Chemical Researches hy Dr. Gobel. 187 



as a very near approximation to the truth, and requiring at 

 least another year's observations, to render it of equal value 

 with that of 1813, which is the result of two years observations 

 with six microscopes, and in four positions of the telescope. 



I am persuaded that the more this subject is considered, the 

 moi-e distinctly it will appear, that if any doubt can be enter- 

 tained, founded on any circumstance arising out of the Dublin 

 observations, that doubt must relate, not to the accuracy of 

 former catalogues, but to the present position of the stars ; 

 since it is with respect to their i:)rcsent position that the two 

 instruments are I'eally at variance. This circumstance is very 

 fortunate, as time may confirm the present or suggest some 

 more satisfactory method of investigation, if what 1 have now 

 advanced be not thought suflicient for the purpose. 



XXXVII. Chemical Researches hy Dr. Friede3Iann 

 GoBEL, of Jena*. 



A. Analysis qfyello-jo Lead Ore. 

 \r LAPROTH has already given us, in his valuable " Con- 

 tributions," an examination of this metallic salt, from 

 which mine considerably differs both in the proportions of the 

 component parts and in the means by which I determined 

 them. 



I obtained for analysis, through the kindness of M. Lenz, 

 some very beautiful regular crystals of this substance. They 

 were rectangular four-sided prisms, the lateral planes of which 

 were uneven, dull, rough, and covered with a little carbonate 

 of lime of a yellowish-white colour. The terminal planes, on 

 the contrary, were smooth and shinuig, with a resinous lustre. 

 The fracture was compact aud obscurely lamellar. The colour 

 of a wax-yellow. It was found at Bleiberg in Carinthia. 



The crystals which were to be decomposed were first washed 

 in dilute nitric acid, to separate the carbonate of lime adhering 

 to them; then carefully washed in water, and dried. 



I. — 100 grs. reduced to a fine powder, and placed with sul- 

 phuric acid in the vacuum of an air-pump for 24< hours, only 

 lost 0"02 grs.; their loss in water was eejually small. 



II. — 100 grs. v,ere dissolved by heat in dilute nuiriatic 

 acid. When cool, a number of crystalline particles of chloride 

 of lead were precipitated, and the jirecipitation was completed 

 l)y a gentle evaporation of the litjuid. The precij)itate, col- 

 lected on a filter, dried and ignited, weighed 72-5 grs. Now 



* Kroiii Scliweigffcr and Meinccke's KucsJounudfurChciiuctind I'/n/si/,-; 

 Xciic Itdlic, Hand 7, p. 71. 



A a 2 lihnnbane 



