My Dear Mr. Faraday,
I was much obliged to you for your kind attention to my request respecting the subscription for the statue to M. Arago1; and I was gratified to find that we had thought of the same sum.
I have examined the interesting specimen of Tourmaline which you requested Dr. Herapath2 to send me3. I have sent him my Report by the same Post which carries this; it expressed my wish that he would shew it to you. It is certainly all Tourmaline, without Quartz or Feldspar.
I am, | My Dear Mr Faraday, | Ever most Truly yours | D. Brewster
St. Leonard’s College | St. Andrews | Novr 24th 1853
P.S. Will you kindly answer the following Queries.
1. What crystals change colour by simply pricking them, and where has any notice of them been published? I think Iodide of Mercury is one, & I think Mr Talbot has somewhere described the experiment4.
2. A Lady in whom I am interested has a Red mark of some extent on her cheek. Would it be safe to apply white lead, or zinc paint to hide it? Or do you [know] of any process for this purpose?
HERAPATH, William Bird (1853): “On the Manufacture of large available Crystals of Sulphate of Iodo-quinine (Herapathite) for Optical Purposes as Artificial Tourmalines”, Phil. Mag., 6: 346-51.
TALBOT, William Henry Fox (1836): “Facts relating to Optical Science. No. III”, Phil. Mag., 9: 1-4.
Please cite as “Faraday2759,” in Ɛpsilon: The Michael Faraday Collection accessed on