Hercules (HPC) 8-K Changes in Registrant.s Certifying Accountant

Exhibit 16.1

April 22, 2005

Securities and Exchange Commission

450 Fifth Street, N.W.

Washington, D.C. 20549

Commissioners:

We have read the statements made by Hercules Incorporated (copy attached), which we understand will be filed with the Commission, pursuant to Item 4.01 of Form 8-K, as part of the Company’s Form 8-K report dated April 18, 2005.  We agree with the statements concerning our Firm in such Form 8-K.

Very truly yours,

PricewaterhouseCoopers LLP