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IX. An Analysis of Satin Spar from Alston Moor in Cumberland. 
By the Rev. John Holme, A.M. F.L.S. 
Read March 17th, 1812. 
Tue extraordinary lustre of the mineral well known at present 
under the appellation of “ Satin Spar*," added to certain other 
circumstances in its external character, induced me to suppose 
that its chemical constituents were not, as commonly believed, 
a simple combination of carbonic acid with lime, but that it 
contained some other ingredient. I resolved, therefore, to under- 
take a careful analysis of tbis substance; and as the result has 
confirmed my conjecture, an account of the process, and the 
proportions of its component parts, may not prove uninteresting 
to the Linnean Society, of which I have the honour to be a 
member. d 
1. A small specimen of very pure satin spar, which weighed 
20 grs., was placed on a piece of iron heated to redness, in order 
to drive off any water which it might contain. | 
2. After the specimen had been in this situation for a few mi- 
nutes, it was taken thence, and again weighed whilst glowing 
with heat. It was then ascertained that the weight of the sub- 
* This mineral has been accurately described by Mr. A. Aikin, and also analysed by 
Mr, H, Pepys jun. but his analysis differs materially from mine.—PAil. Mag. vol. xii. 
“stance 
