Another mystery

Ruh Roh!

The Japy case was described as "black slate" by the seller. Sounds fine to me. 

And then one day I'm reading the NAWCC message boards and came across a thread describing a clock very similar to mine. So similar that I had to jump in. The story is there in the thread but I'll summarize here first. 

Marc from York, UK (this is an international thriller!) posted about his white stone Japy Freres 1855 Exposition clock.

Well I'll be darned.

Definitely some differences, most notably that the movement is time and strike (mine being time only) but the same makers mark from 1855. 

Entertaining to see one. 

In the course of the thread Marc wants to identify the type of stone used for the case. Is is marble? Alabaster? Something else? I speculated on the thread that the stone looked like Alabaster but I am no expert.

I was fascinated and dug into Thorpe and researched the message boards.

Is my clock black slate or something else? 

Well Thorpe has an extensive section in his book on the historical quarrying of stone for the production of these clocks. 

"It is common knowledge that much of the stone used in the construction of French marble clock cases came from Belgium, although there has always been some doubt whether this stone was a true marble. At various times the clocks have been called 'marble clocks', 'Belgian slate clocks', 'Belgian limestone clocks', or merely 'slate clocks'."

He later states the stone is "... 'calcareous marble', a term that I believe should be applied to most Belgian black marbles."

AND he describes a simple test that will tell you if the stone is marble...

"Marble has one property that differentiates it from slate; it effervesces in contact with acid."

Here's from my posting on the board:

"There is a simple test to see if a stone is marble. It will cause a tiny effervescence (bubbling) when exposed to acid. Slate will not bubble. I did some quick checks on here on the boards and saw several other threads that mention this same test using lemon juice on a part of the case away from regular sight (like the underside).

Thorpe says the bubbles will be quite tiny but numerous.

I tried it. My case has a little chip in it’s edge. I got a drop of fresh lemon juice.

We have bubbles."

And here's the picture I posted (click it to see the large photo):

How cool is that?

It's Belgian black marble.

Oh here's the thread.