1824.] Scientific Notices — Mineralogy. 155 



The carbonate of lead is undoubtedly an accidental admixture, 

 as its proportion, on a repetition of the analysis, was found to 

 vary in different parts of the mineral, being least abundant in the 

 centre, and increasing in quantity towards the edges, where the 

 mass is incorporated with the carbonate of lead which consti- 

 tutes, as it were, its matrix. 



He considers the proximate ingredients of the portion, whose 

 analysis we have stated above, to have been 



Chloride of lead 34-63 1 atom 



Oxide of lead 55*82 2 atoms 



Carbonate of lead .... 7*55 



Silica 1-46 



Water 0-54 



100-00 



This mineral differs from the horn lead analyzed by Klaproth 

 and Chenevix, which possesses a rectangular cleavage, and 

 consists, as has been demonstrated pretty decisively by Berze- 

 lius (Afh. i Fysik, Kemi och Min. iv. 125), of an atom of chlo- 

 ride of lead united to an atom of carbonate of lead. It differs 

 also from the ordinary artificial submuriate, which is composed 

 of 1 atom of chloride of lead and 3 atoms of oxide of lead. — 

 (Kongl. Vet. Acad.Handl. 1823, St. 1.) 



13. Mountain Tallotv. 



Specimens of this mineral substance were lately found in a 

 bog on the borders of Loch Fyne. This curious mineral was 

 first observed by some peasants on the coast of Finland in 1736 ; 

 afterwards it was found in one of the Swedish lakes. M. Herman, 

 physician at Strasburgh, observed a similar substance in the 

 water of a fountain near that city ; and Prof. Jameson met with 

 it in this country. It has the colour and feel of tallow, and is 

 tasteless. The following notice in regard to it was sent to us : — 

 It melts at 118°, and boils at 290°; when melted, it is transpa- 

 rent and colourless ; on cooling, becomes opaque and white, 

 though not so much so as at first. It is insoluble in water, but 

 soluble in alcohol, oil of turpentine, olive oil, and naphtha, while 

 these liquids are hot, but it is precipitated again when they cool. 

 Its specific gravity in the natural state of it, is O6078 ; but the 

 tallow is full of air-bubbles, and, after fusion, which disengages 

 the air, the specific gravity is 0-983, which is rather higher than 

 that of tallow. It does not combine with alkalies, nor form 

 soap. Thus it differs from every class of bodies known ; from 

 the fixed oils in not forming soap ; from the volatile oils and 

 bitumens, in being tasteless and destitute of smell. Its volati- 

 lity and combustibility are equal to those of any volatile oil or 

 naphtha. — (Edin. Phil. Jour.) 



