June 29, 2007

U.S. Securities and Exchange Commission
Office of the Chief Accountant
100 F Street, NE
Washington, DC 20549

Re: O. I. Corporation
File No. 0-6511

Dear Sir or Madam:

We have read Item 4.01 of Form 8-K of O. I. Corporation dated June 29, 2007, and agree with the statements concerning our Firm contained therein.

Very truly yours,

/s/ Grant Thornton LLP