I hope to save a few pages of a book freely available at Google Books: Page 218-223 of Richard Hittleman's Yoga: 28 Day Exercise Plan. I am using Ubuntu and preferably Firefox.
How would I do that?
This is a greasemonkey script that works under Firefox. I have tested this under a Windows 7 machine as I don't have access to a Ubuntu machine here with me.
To download a book (or the preview pages you can see) from Google Books
For the current page your viewing there is a download image that looks like a floppy disk with PA### where ### is the current page on the right hand side of the page. Clicking this will allow you to download the single page.
Do you mean the eBook is freely available? If so, it could be country restricted as I don't see it.
Assuming you can access the PDF copy, try opening it in Chrome. Chrome would open the PDF using its native PDF Viewer. With the keyboard shortcut Ctrl+P, you can invoke the Print Dialog box within Chrome. Set the Destination option there to "Print to PDF" & instead of selecting "All" for pages, set the page range that you require.
Alternatively, you can install CutePDF Writer which can print any document to PDF and then print the range of PDF pages as a new PDF.
Edit: Looks like you need to be in US and you only get first 30 pages, therefore your out of luck. Sorry.
Google only overs a preview if the author has uploaded pages of it and made those available as preview or if they made it free.
Here is what the page you linked to would look like if you could preview it:
As you can see your book your looking at has no preview button:
Therefore you cannot preview the book it's only available for purchase.