CHEMICAL SCIENCE. 173 



wholly overlooked — owing perhaps to the circumstance that as an alloy with 

 certain metals cadmium does not promote fusibility. 



" Cadmium promotes the fusibility of some metals, as copper, tin, lead, bis- 

 muth, while it does not promote the fusibility of others, as silver, antimony, 

 mercury, &c. (i.e., does not lower the melting-point beyond the mean). Its 

 alloy with lead and tin in any proportion, and with silver and mercury within a 

 certain limit, say, equal parts, and especially if two parts silver and one of cad- 

 mium or two parts cadmium and one of mercury are used, are tenacious and 

 malleable, while its alloys with some malleable metals (gold, copper, platinum, 

 Ac.), and probably with all brittle metals, are ' brittle.' 



"I notice a great discrepancy among authors as to the melting-point of this 

 metal. It is usually put down the same as that of tin (442° F.). Brande (Diet, 

 of Science and Arts) says it 'fuses and volatilizes at a temperature a little below 

 that at which tiu melts.' Daniell (according to the IS r ew American Cyclopaedia) 

 gives its melting-point at 360° F. ; while Overman places it at 550°, and gives 

 600° as the temperature at which it volatilizes. 



" The latter is doubtless the nearest the truth. The metal requires for its 

 fusion a temperature too high for measurement by the mercurial thermometer ; 

 but from relative tests with other metals I should place its melting-point in round 

 numbers at 600° F., as it melts and congeals nearly synchronously with lead, the 

 melting-point of which is stated by difl'erent authorities as 594°, 600°, and 612° 

 F. It volatilizes at a somewhat higher heat. 



"I draw attention to these facts, believing that the metal possesses properties 

 valuable to art and interesting in science, and that it merits more thorough in- 

 vestigation than appears to have been bestowed upon it." — Sillimau's American 

 Journal, September, 1860. 



CARBONATE OF LEAD FROM LEADEN COFFINS. 



Mr. Richard V. Tuson, Lecturer on Chemistry at Charing Cross 

 Hospital, states, in the Philosophical Magazine, No. 127 : — 



About twelve months ago an Order of Council was issued directing 

 the coffins in the vaults of the church of St. Martin's-in-the- Fields to 

 be transferred to the catacombs. A few days after the appearance of 

 this order, my friend and colleague, Mr. Canton, in company with 

 several other gentlemen, visited the vaults with the view of endea- 

 vouring to find the remains of the late celebrated surgeon, John 

 Hunter, which were known to have been deposited there. The 

 search proved successful, and Hunter's remains were subsequently 

 reinterred in Westminster Abbey. 



During his visit, Mr. Canton observed that many of the leaden 

 coffins, although they retained their original shape, were, with the 

 exception of an external and exceedingly thin plate or foil of metal, 

 converted into an earthy-looking substance. Several pieces of this 

 substance were removed from a coffin which, there is good reason for 

 believing, had been in the vaults about eighty years. These were 

 placed at my disposal ; and although it was thought that they prin- 

 cipally consisted of carbonate of lead, it was nevertheless considered, 

 from the peculiarity of the circumstances under which the material 

 was formed, that the results of its analysis might prove somewhat 

 interesting. 



The pieces of the substance referred to were about a quarter of an 

 inch in thickness : they had a laminated structure, and possessed a 

 fawnish or drab- white colour. Neither crystalline form nor metallic 

 lead were detected even by the aid of the microscope. The material 

 was tolerably brittle, and readily reduced to an impalpable powder. 



