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XXXIX. On a Carbonate of Lead from Leaden Coffins. By 
Ricuarp V. Tuson, Lecturer on Chemistry at Charing Cross 
Hospital*. 
pa eOUT twelve months ago an Order of Council was issued 
directing the coffins in the vaults of the church of St. Mar- 
tin’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 endeavouring to find the remains of 
the late celebrated surgeon, John Hunter, which were known to 
have been deposited there. The search proved successful, and 
he remains were subsequently reinterred in Westminster 
ey. 
ae 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 
ears. These were placed at my disposal; and although it was 
thought that they principally consisted of carbonate of lead, it 
was nevertheless considered, from the peculiarity of the circum- 
stances 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. On submitting it to quanti- 
tative analysis, the following were the results obtained :— 
meamtgre so SOD 
Organic matter and loss. 0°52 
Peroxide of iron . . . 1:94 
Protoxide of lead. . . 82°29) _ f PbO,CO? 92:28 
Carbonic acid. . . . 15°15 f ~ | +PbO 5°16 
100-00 
The results of the analysis of this substance, therefore, show 
that it chiefly consists of protocarbonate of lead with a small 
proportion of anhydrous protoxide of the same metal. The pro- 
duction of these compounds was doubtless mainly due to the 
* Communicated by.the Author. 
